thodg/libgit2

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c937ba9..53f568e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -361,7 +361,7 @@ IF (BUILD_CLAR)
 
 	ADD_CUSTOM_COMMAND(
 		OUTPUT ${CLAR_PATH}/clar.suite
-		COMMAND ${PYTHON_EXECUTABLE} generate.py -f -xonline .
+		COMMAND ${PYTHON_EXECUTABLE} generate.py -f -xonline -xstress .
 		DEPENDS ${SRC_TEST}
 		WORKING_DIRECTORY ${CLAR_PATH}
 	)
diff --git a/src/array.h b/src/array.h
index 2480104..c25a1b2 100644
--- a/src/array.h
+++ b/src/array.h
@@ -39,25 +39,26 @@
 #define GITERR_CHECK_ARRAY(a) GITERR_CHECK_ALLOC((a).ptr)
 
 
-typedef git_array_t(void) git_array_generic_t;
+typedef git_array_t(char) git_array_generic_t;
 
 /* use a generic array for growth so this can return the new item */
-GIT_INLINE(void *) git_array_grow(git_array_generic_t *a, size_t item_size)
+GIT_INLINE(void *) git_array_grow(void *_a, size_t item_size)
 {
+	git_array_generic_t *a = _a;
 	uint32_t new_size = (a->size < 8) ? 8 : a->asize * 3 / 2;
-	void *new_array = git__realloc(a->ptr, new_size * item_size);
+	char *new_array = git__realloc(a->ptr, new_size * item_size);
 	if (!new_array) {
 		git_array_clear(*a);
 		return NULL;
 	} else {
 		a->ptr = new_array; a->asize = new_size; a->size++;
-		return (((char *)a->ptr) + (a->size - 1) * item_size);
+		return a->ptr + (a->size - 1) * item_size;
 	}
 }
 
 #define git_array_alloc(a) \
 	((a).size >= (a).asize) ? \
-	git_array_grow((git_array_generic_t *)&(a), sizeof(*(a).ptr)) :	\
+	git_array_grow(&(a), sizeof(*(a).ptr)) : \
 	(a).ptr ? &(a).ptr[(a).size++] : NULL
 
 #define git_array_last(a) ((a).size ? &(a).ptr[(a).size - 1] : NULL)
diff --git a/src/blob.c b/src/blob.c
index 2e4d5f4..5bb51f7 100644
--- a/src/blob.c
+++ b/src/blob.c
@@ -105,6 +105,7 @@ static int write_file_stream(
 
 static int write_file_filtered(
 	git_oid *oid,
+	git_off_t *size,
 	git_odb *odb,
 	const char *full_path,
 	git_vector *filters)
@@ -123,8 +124,11 @@ static int write_file_filtered(
 	git_buf_free(&source);
 
 	/* Write the file to disk if it was properly filtered */
-	if (!error)
+	if (!error) {
+		*size = dest.size;
+
 		error = git_odb_write(oid, odb, dest.ptr, dest.size, GIT_OBJ_BLOB);
+	}
 
 	git_buf_free(&dest);
 	return error;
@@ -152,21 +156,46 @@ static int write_symlink(
 	return error;
 }
 
-static int blob_create_internal(git_oid *oid, git_repository *repo, const char *content_path, const char *hint_path, bool try_load_filters)
+int git_blob__create_from_paths(
+	git_oid *oid,
+	struct stat *out_st,
+	git_repository *repo,
+	const char *content_path,
+	const char *hint_path,
+	mode_t hint_mode,
+	bool try_load_filters)
 {
 	int error;
 	struct stat st;
 	git_odb *odb = NULL;
 	git_off_t size;
+	mode_t mode;
+	git_buf path = GIT_BUF_INIT;
 
 	assert(hint_path || !try_load_filters);
 
-	if ((error = git_path_lstat(content_path, &st)) < 0 || (error = git_repository_odb__weakptr(&odb, repo)) < 0)
-		return error;
+	if (!content_path) {
+		if (git_repository__ensure_not_bare(repo, "create blob from file") < 0)
+			return GIT_EBAREREPO;
+
+		if (git_buf_joinpath(
+				&path, git_repository_workdir(repo), hint_path) < 0)
+			return -1;
+
+		content_path = path.ptr;
+	}
+
+	if ((error = git_path_lstat(content_path, &st)) < 0 ||
+		(error = git_repository_odb(&odb, repo)) < 0)
+		goto done;
+
+	if (out_st)
+		memcpy(out_st, &st, sizeof(st));
 
 	size = st.st_size;
+	mode = hint_mode ? hint_mode : st.st_mode;
 
-	if (S_ISLNK(st.st_mode)) {
+	if (S_ISLNK(mode)) {
 		error = write_symlink(oid, odb, content_path, (size_t)size);
 	} else {
 		git_vector write_filters = GIT_VECTOR_INIT;
@@ -187,7 +216,8 @@ static int blob_create_internal(git_oid *oid, git_repository *repo, const char *
 			error = write_file_stream(oid, odb, content_path, size);
 		} else {
 			/* We need to apply one or more filters */
-			error = write_file_filtered(oid, odb, content_path, &write_filters);
+			error = write_file_filtered(
+				oid, &size, odb, content_path, &write_filters);
 		}
 
 		git_filters_free(&write_filters);
@@ -207,34 +237,21 @@ static int blob_create_internal(git_oid *oid, git_repository *repo, const char *
 		 */
 	}
 
+done:
+	git_odb_free(odb);
+	git_buf_free(&path);
+
 	return error;
 }
 
-int git_blob_create_fromworkdir(git_oid *oid, git_repository *repo, const char *path)
+int git_blob_create_fromworkdir(
+	git_oid *oid, git_repository *repo, const char *path)
 {
-	git_buf full_path = GIT_BUF_INIT;
-	const char *workdir;
-	int error;
-
-	if ((error = git_repository__ensure_not_bare(repo, "create blob from file")) < 0)
-		return error;
-
-	workdir = git_repository_workdir(repo);
-
-	if (git_buf_joinpath(&full_path, workdir, path) < 0) {
-		git_buf_free(&full_path);
-		return -1;
-	}
-
-	error = blob_create_internal(
-		oid, repo, git_buf_cstr(&full_path),
-		git_buf_cstr(&full_path) + strlen(workdir), true);
-
-	git_buf_free(&full_path);
-	return error;
+	return git_blob__create_from_paths(oid, NULL, repo, NULL, path, 0, true);
 }
 
-int git_blob_create_fromdisk(git_oid *oid, git_repository *repo, const char *path)
+int git_blob_create_fromdisk(
+	git_oid *oid, git_repository *repo, const char *path)
 {
 	int error;
 	git_buf full_path = GIT_BUF_INIT;
@@ -251,8 +268,8 @@ int git_blob_create_fromdisk(git_oid *oid, git_repository *repo, const char *pat
 	if (workdir && !git__prefixcmp(hintpath, workdir))
 		hintpath += strlen(workdir);
 
-	error = blob_create_internal(
-		oid, repo, git_buf_cstr(&full_path), hintpath, true);
+	error = git_blob__create_from_paths(
+		oid, NULL, repo, git_buf_cstr(&full_path), hintpath, 0, true);
 
 	git_buf_free(&full_path);
 	return error;
@@ -272,12 +289,9 @@ int git_blob_create_fromchunks(
 	git_filebuf file = GIT_FILEBUF_INIT;
 	git_buf path = GIT_BUF_INIT;
 
-	if (git_buf_join_n(
-		&path, '/', 3, 
-		git_repository_path(repo),
-		GIT_OBJECTS_DIR, 
-		"streamed") < 0)
-			goto cleanup;
+	if (git_buf_joinpath(
+			&path, git_repository_path(repo), GIT_OBJECTS_DIR "streamed") < 0)
+		goto cleanup;
 
 	content = git__malloc(BUFFER_SIZE);
 	GITERR_CHECK_ALLOC(content);
@@ -303,7 +317,8 @@ int git_blob_create_fromchunks(
 	if (git_filebuf_flush(&file) < 0)
 		goto cleanup;
 
-	error = blob_create_internal(oid, repo, file.path_lock, hintpath, hintpath != NULL);
+	error = git_blob__create_from_paths(
+		oid, NULL, repo, file.path_lock, hintpath, 0, hintpath != NULL);
 
 cleanup:
 	git_buf_free(&path);
diff --git a/src/blob.h b/src/blob.h
index 22e37cc..4cd9f1e 100644
--- a/src/blob.h
+++ b/src/blob.h
@@ -21,4 +21,13 @@ void git_blob__free(void *blob);
 int git_blob__parse(void *blob, git_odb_object *obj);
 int git_blob__getbuf(git_buf *buffer, git_blob *blob);
 
+extern int git_blob__create_from_paths(
+	git_oid *out_oid,
+	struct stat *out_st,
+	git_repository *repo,
+	const char *full_path,
+	const char *hint_path,
+	mode_t hint_mode,
+	bool apply_filters);
+
 #endif
diff --git a/src/diff.h b/src/diff.h
index d09a130..d1bec00 100644
--- a/src/diff.h
+++ b/src/diff.h
@@ -16,6 +16,7 @@
 #include "iterator.h"
 #include "repository.h"
 #include "pool.h"
+#include "odb.h"
 
 #define DIFF_OLD_PREFIX_DEFAULT "a/"
 #define DIFF_NEW_PREFIX_DEFAULT "b/"
@@ -108,5 +109,33 @@ extern void git_diff_find_similar__hashsig_free(void *sig, void *payload);
 extern int git_diff_find_similar__calc_similarity(
 	int *score, void *siga, void *sigb, void *payload);
 
+/*
+ * Sometimes a git_diff_file will have a zero size; this attempts to
+ * fill in the size without loading the blob if possible.  If that is
+ * not possible, then it will return the git_odb_object that had to be
+ * loaded and the caller can use it or dispose of it as needed.
+ */
+GIT_INLINE(int) git_diff_file__resolve_zero_size(
+	git_diff_file *file, git_odb_object **odb_obj, git_repository *repo)
+{
+	int error;
+	git_odb *odb;
+	size_t len;
+	git_otype type;
+
+	if ((error = git_repository_odb(&odb, repo)) < 0)
+		return error;
+
+	error = git_odb__read_header_or_object(
+		odb_obj, &len, &type, odb, &file->oid);
+
+	git_odb_free(odb);
+
+	if (!error)
+		file->size = (git_off_t)len;
+
+	return error;
+}
+
 #endif
 
diff --git a/src/diff_file.c b/src/diff_file.c
index 9d06daa..bcfef13 100644
--- a/src/diff_file.c
+++ b/src/diff_file.c
@@ -241,19 +241,9 @@ static int diff_file_content_load_blob(git_diff_file_content *fc)
 
 	/* if we don't know size, try to peek at object header first */
 	if (!fc->file->size) {
-		git_odb *odb;
-		size_t len;
-		git_otype type;
-
-		if (!(error = git_repository_odb__weakptr(&odb, fc->repo))) {
-			error = git_odb__read_header_or_object(
-				&odb_obj, &len, &type, odb, &fc->file->oid);
-			git_odb_free(odb);
-		}
-		if (error)
+		if ((error = git_diff_file__resolve_zero_size(
+				fc->file, &odb_obj, fc->repo)) < 0)
 			return error;
-
-		fc->file->size = len;
 	}
 
 	if (diff_file_content_binary_by_size(fc))
@@ -417,6 +407,9 @@ int git_diff_file_content__load(git_diff_file_content *fc)
 
 void git_diff_file_content__unload(git_diff_file_content *fc)
 {
+	if ((fc->flags & GIT_DIFF_FLAG__LOADED) == 0)
+		return;
+
 	if (fc->flags & GIT_DIFF_FLAG__FREE_DATA) {
 		git__free(fc->map.data);
 		fc->map.data = "";
diff --git a/src/diff_patch.c b/src/diff_patch.c
index 1b4adac..69bb081 100644
--- a/src/diff_patch.c
+++ b/src/diff_patch.c
@@ -230,6 +230,10 @@ static int diff_patch_generate(git_diff_patch *patch, git_diff_output *output)
 	if ((patch->flags & GIT_DIFF_PATCH_DIFFED) != 0)
 		return 0;
 
+	/* if we are not looking at the hunks and lines, don't do the diff */
+	if (!output->hunk_cb && !output->data_cb)
+		return 0;
+
 	if ((patch->flags & GIT_DIFF_PATCH_LOADED) == 0 &&
 		(error = diff_patch_load(patch, output)) < 0)
 		return error;
@@ -284,8 +288,8 @@ int git_diff_foreach(
 	if (diff_required(diff, "git_diff_foreach") < 0)
 		return -1;
 
-	diff_output_init((git_diff_output *)&xo,
-		&diff->opts, file_cb, hunk_cb, data_cb, payload);
+	diff_output_init(
+		&xo.output, &diff->opts, file_cb, hunk_cb, data_cb, payload);
 	git_xdiff_init(&xo, &diff->opts);
 
 	git_vector_foreach(&diff->deltas, idx, patch.delta) {
@@ -296,10 +300,10 @@ int git_diff_foreach(
 
 		if (!(error = diff_patch_init_from_diff(&patch, diff, idx))) {
 
-			error = diff_patch_file_callback(&patch, (git_diff_output *)&xo);
+			error = diff_patch_file_callback(&patch, &xo.output);
 
 			if (!error)
-				error = diff_patch_generate(&patch, (git_diff_output *)&xo);
+				error = diff_patch_generate(&patch, &xo.output);
 
 			git_diff_patch_free(&patch);
 		}
@@ -437,7 +441,7 @@ int git_diff_blobs(
 	memset(&xo, 0, sizeof(xo));
 
 	diff_output_init(
-		(git_diff_output *)&xo, opts, file_cb, hunk_cb, data_cb, payload);
+		&xo.output, opts, file_cb, hunk_cb, data_cb, payload);
 	git_xdiff_init(&xo, opts);
 
 	if (!old_path && new_path)
@@ -448,7 +452,7 @@ int git_diff_blobs(
 	error = diff_patch_from_blobs(
 		&pd, &xo, old_blob, old_path, new_blob, new_path, opts);
 
-	git_diff_patch_free((git_diff_patch *)&pd);
+	git_diff_patch_free(&pd.patch);
 
 	return error;
 }
@@ -473,7 +477,7 @@ int git_diff_patch_from_blobs(
 
 	memset(&xo, 0, sizeof(xo));
 
-	diff_output_to_patch((git_diff_output *)&xo, &pd->patch);
+	diff_output_to_patch(&xo.output, &pd->patch);
 	git_xdiff_init(&xo, opts);
 
 	error = diff_patch_from_blobs(
@@ -549,7 +553,7 @@ int git_diff_blob_to_buffer(
 	memset(&xo, 0, sizeof(xo));
 
 	diff_output_init(
-		(git_diff_output *)&xo, opts, file_cb, hunk_cb, data_cb, payload);
+		&xo.output, opts, file_cb, hunk_cb, data_cb, payload);
 	git_xdiff_init(&xo, opts);
 
 	if (!old_path && buf_path)
@@ -560,7 +564,7 @@ int git_diff_blob_to_buffer(
 	error = diff_patch_from_blob_and_buffer(
 		&pd, &xo, old_blob, old_path, buf, buflen, buf_path, opts);
 
-	git_diff_patch_free((git_diff_patch *)&pd);
+	git_diff_patch_free(&pd.patch);
 
 	return error;
 }
@@ -586,7 +590,7 @@ int git_diff_patch_from_blob_and_buffer(
 
 	memset(&xo, 0, sizeof(xo));
 
-	diff_output_to_patch((git_diff_output *)&xo, &pd->patch);
+	diff_output_to_patch(&xo.output, &pd->patch);
 	git_xdiff_init(&xo, opts);
 
 	error = diff_patch_from_blob_and_buffer(
@@ -638,13 +642,13 @@ int git_diff_get_patch(
 	if ((error = diff_patch_alloc_from_diff(&patch, diff, idx)) < 0)
 		return error;
 
-	diff_output_to_patch((git_diff_output *)&xo, patch);
+	diff_output_to_patch(&xo.output, patch);
 	git_xdiff_init(&xo, &diff->opts);
 
-	error = diff_patch_file_callback(patch, (git_diff_output *)&xo);
+	error = diff_patch_file_callback(patch, &xo.output);
 
 	if (!error)
-		error = diff_patch_generate(patch, (git_diff_output *)&xo);
+		error = diff_patch_generate(patch, &xo.output);
 
 	if (!error) {
 		/* if cumulative diff size is < 0.5 total size, flatten the patch */
diff --git a/src/diff_tform.c b/src/diff_tform.c
index ac5356a..ba35d3c 100644
--- a/src/diff_tform.c
+++ b/src/diff_tform.c
@@ -408,57 +408,99 @@ GIT_INLINE(git_diff_file *) similarity_get_file(git_diff_list *diff, size_t idx)
 	return (idx & 1) ? &delta->new_file : &delta->old_file;
 }
 
-static int similarity_calc(
-	git_diff_list *diff,
+typedef struct {
+	size_t idx;
+	git_iterator_type_t src;
+	git_repository *repo;
+	git_diff_file *file;
+	git_buf data;
+	git_odb_object *odb_obj;
+	git_blob *blob;
+} similarity_info;
+
+static int similarity_init(
+	similarity_info *info, git_diff_list *diff, size_t file_idx)
+{
+	info->idx  = file_idx;
+	info->src  = (file_idx & 1) ? diff->new_src : diff->old_src;
+	info->repo = diff->repo;
+	info->file = similarity_get_file(diff, file_idx);
+	info->odb_obj = NULL;
+	info->blob = NULL;
+	git_buf_init(&info->data, 0);
+
+	if (info->file->size > 0)
+		return 0;
+
+	return git_diff_file__resolve_zero_size(
+		info->file, &info->odb_obj, info->repo);
+}
+
+static int similarity_sig(
+	similarity_info *info,
 	const git_diff_find_options *opts,
-	size_t file_idx,
 	void **cache)
 {
 	int error = 0;
-	git_diff_file *file = similarity_get_file(diff, file_idx);
-	git_iterator_type_t src = (file_idx & 1) ? diff->new_src : diff->old_src;
-
-	if (src == GIT_ITERATOR_TYPE_WORKDIR) { /* compute hashsig from file */
-		git_buf path = GIT_BUF_INIT;
-
-		/* TODO: apply wd-to-odb filters to file data if necessary */
+	git_diff_file *file = info->file;
 
+	if (info->src == GIT_ITERATOR_TYPE_WORKDIR) {
 		if ((error = git_buf_joinpath(
-				 &path, git_repository_workdir(diff->repo), file->path)) < 0)
+			&info->data, git_repository_workdir(info->repo), file->path)) < 0)
 			return error;
 
 		/* if path is not a regular file, just skip this item */
-		if (git_path_isfile(path.ptr))
-			error = opts->metric->file_signature(
-				&cache[file_idx], file, path.ptr, opts->metric->payload);
+		if (!git_path_isfile(info->data.ptr))
+			return 0;
 
-		git_buf_free(&path);
-	} else { /* compute hashsig from blob buffer */
-		git_blob *blob = NULL;
-		git_off_t blobsize;
+		/* TODO: apply wd-to-odb filters to file data if necessary */
 
-		/* TODO: add max size threshold a la diff? */
+		error = opts->metric->file_signature(
+			&cache[info->idx], info->file,
+			info->data.ptr, opts->metric->payload);
+	} else {
+		/* if we didn't initially know the size, we might have an odb_obj
+		 * around from earlier, so convert that, otherwise load the blob now
+		 */
+		if (info->odb_obj != NULL)
+			error = git_object__from_odb_object(
+				(git_object **)&info->blob, info->repo,
+				info->odb_obj, GIT_OBJ_BLOB);
+		else
+			error = git_blob_lookup(&info->blob, info->repo, &file->oid);
 
-		if (git_blob_lookup(&blob, diff->repo, &file->oid) < 0) {
+		if (error < 0) {
 			/* if lookup fails, just skip this item in similarity calc */
 			giterr_clear();
-			return 0;
-		}
+		} else {
+			size_t sz;
 
-		blobsize = git_blob_rawsize(blob);
-		if (!git__is_sizet(blobsize)) /* ? what to do ? */
-			blobsize = (size_t)-1;
+			/* index size may not be actual blob size if filtered */
+			if (file->size != git_blob_rawsize(info->blob))
+				file->size = git_blob_rawsize(info->blob);
 
-		error = opts->metric->buffer_signature(
-			&cache[file_idx], file, git_blob_rawcontent(blob),
-			(size_t)blobsize, opts->metric->payload);
+			sz = (size_t)(git__is_sizet(file->size) ? file->size : -1);
 
-		git_blob_free(blob);
+			error = opts->metric->buffer_signature(
+				&cache[info->idx], info->file,
+				git_blob_rawcontent(info->blob), sz, opts->metric->payload);
+		}
 	}
 
 	return error;
 }
 
+static void similarity_unload(similarity_info *info)
+{
+	if (info->odb_obj)
+		git_odb_object_free(info->odb_obj);
+
+	if (info->blob)
+		git_blob_free(info->blob);
+	else
+		git_buf_free(&info->data);
+}
+
 #define FLAG_SET(opts,flag_name) (((opts)->flags & flag_name) != 0)
 
 /* - score < 0 means files cannot be compared
@@ -476,6 +518,8 @@ static int similarity_measure(
 	git_diff_file *a_file = similarity_get_file(diff, a_idx);
 	git_diff_file *b_file = similarity_get_file(diff, b_idx);
 	bool exact_match = FLAG_SET(opts, GIT_DIFF_FIND_EXACT_MATCH_ONLY);
+	int error = 0;
+	similarity_info a_info, b_info;
 
 	*score = -1;
 
@@ -510,19 +554,44 @@ static int similarity_measure(
 		return 0;
 	}
 
+	memset(&a_info, 0, sizeof(a_info));
+	memset(&b_info, 0, sizeof(b_info));
+
+	/* set up similarity data (will try to update missing file sizes) */
+	if (!cache[a_idx] && (error = similarity_init(&a_info, diff, a_idx)) < 0)
+		return error;
+	if (!cache[b_idx] && (error = similarity_init(&b_info, diff, b_idx)) < 0)
+		goto cleanup;
+
+	/* check if file sizes are nowhere near each other */
+	if (a_file->size > 127 &&
+		b_file->size > 127 &&
+		(a_file->size > (b_file->size << 3) ||
+		 b_file->size > (a_file->size << 3)))
+		goto cleanup;
+
 	/* update signature cache if needed */
-	if (!cache[a_idx] && similarity_calc(diff, opts, a_idx, cache) < 0)
-		return -1;
-	if (!cache[b_idx] && similarity_calc(diff, opts, b_idx, cache) < 0)
-		return -1;
+	if (!cache[a_idx]) {
+		if ((error = similarity_sig(&a_info, opts, cache)) < 0)
+			goto cleanup;
+	}
+	if (!cache[b_idx]) {
+		if ((error = similarity_sig(&b_info, opts, cache)) < 0)
+			goto cleanup;
+	}
 
-	/* some metrics may not wish to process this file (too big / too small) */
-	if (!cache[a_idx] || !cache[b_idx])
-		return 0;
+	/* calculate similarity provided that the metric choose to process
+	 * both the a and b files (some may not if file is too big, etc).
+	 */
+	if (cache[a_idx] && cache[b_idx])
+		error = opts->metric->similarity(
+			score, cache[a_idx], cache[b_idx], opts->metric->payload);
+
+cleanup:
+	similarity_unload(&a_info);
+	similarity_unload(&b_info);
 
-	/* compare signatures */
-	return opts->metric->similarity(
-		score, cache[a_idx], cache[b_idx], opts->metric->payload);
+	return error;
 }
 
 static int calc_self_similarity(
@@ -693,25 +762,30 @@ int git_diff_find_similar(
 	git_diff_list *diff,
 	git_diff_find_options *given_opts)
 {
-	size_t i, j, sigcache_size;
+	size_t s, t;
 	int error = 0, similarity;
-	git_diff_delta *from, *to;
+	git_diff_delta *src, *tgt;
 	git_diff_find_options opts;
-	size_t num_srcs = 0, num_tgts = 0, tried_srcs = 0, tried_tgts = 0;
+	size_t num_deltas, num_srcs = 0, num_tgts = 0;
+	size_t tried_srcs = 0, tried_tgts = 0;
 	size_t num_rewrites = 0, num_updates = 0, num_bumped = 0;
 	void **sigcache; /* cache of similarity metric file signatures */
-	diff_find_match *match_srcs = NULL, *match_tgts = NULL, *best_match;
+	diff_find_match *tgt2src = NULL;
+	diff_find_match *src2tgt = NULL;
+	diff_find_match *tgt2src_copy = NULL;
+	diff_find_match *best_match;
 	git_diff_file swap;
 
 	if ((error = normalize_find_opts(diff, &opts, given_opts)) < 0)
 		return error;
 
+	num_deltas = diff->deltas.length;
+
 	/* TODO: maybe abort if deltas.length > rename_limit ??? */
-	if (!git__is_uint32(diff->deltas.length))
+	if (!git__is_uint32(num_deltas))
 		return 0;
 
-	sigcache_size = diff->deltas.length * 2; /* keep size b/c diff may change */
-	sigcache = git__calloc(sigcache_size, sizeof(void *));
+	sigcache = git__calloc(num_deltas * 2, sizeof(void *));
 	GITERR_CHECK_ALLOC(sigcache);
 
 	/* Label rename sources and targets
@@ -719,11 +793,11 @@ int git_diff_find_similar(
 	 * This will also set self-similarity scores for MODIFIED files and
 	 * mark them for splitting if break-rewrites is enabled
 	 */
-	git_vector_foreach(&diff->deltas, i, to) {
-		if (is_rename_source(diff, &opts, i, sigcache))
+	git_vector_foreach(&diff->deltas, t, tgt) {
+		if (is_rename_source(diff, &opts, t, sigcache))
 			++num_srcs;
 
-		if (is_rename_target(diff, &opts, i, sigcache))
+		if (is_rename_target(diff, &opts, t, sigcache))
 			++num_tgts;
 	}
 
@@ -731,10 +805,15 @@ int git_diff_find_similar(
 	if (!num_srcs || !num_tgts)
 		goto cleanup;
 
-	match_tgts = git__calloc(diff->deltas.length, sizeof(diff_find_match));
-	GITERR_CHECK_ALLOC(match_tgts);
-	match_srcs = git__calloc(diff->deltas.length, sizeof(diff_find_match));
-	GITERR_CHECK_ALLOC(match_srcs);
+	src2tgt = git__calloc(num_deltas, sizeof(diff_find_match));
+	GITERR_CHECK_ALLOC(src2tgt);
+	tgt2src = git__calloc(num_deltas, sizeof(diff_find_match));
+	GITERR_CHECK_ALLOC(tgt2src);
+
+	if (FLAG_SET(&opts, GIT_DIFF_FIND_COPIES)) {
+		tgt2src_copy = git__calloc(num_deltas, sizeof(diff_find_match));
+		GITERR_CHECK_ALLOC(tgt2src_copy);
+	}
 
 	/*
 	 * Find best-fit matches for rename / copy candidates
@@ -743,47 +822,61 @@ int git_diff_find_similar(
 find_best_matches:
 	tried_tgts = num_bumped = 0;
 
-	git_vector_foreach(&diff->deltas, i, to) {
+	git_vector_foreach(&diff->deltas, t, tgt) {
 		/* skip things that are not rename targets */
-		if ((to->flags & GIT_DIFF_FLAG__IS_RENAME_TARGET) == 0)
+		if ((tgt->flags & GIT_DIFF_FLAG__IS_RENAME_TARGET) == 0)
 			continue;
 
 		tried_srcs = 0;
 
-		git_vector_foreach(&diff->deltas, j, from) {
+		git_vector_foreach(&diff->deltas, s, src) {
 			/* skip things that are not rename sources */
-			if ((from->flags & GIT_DIFF_FLAG__IS_RENAME_SOURCE) == 0)
+			if ((src->flags & GIT_DIFF_FLAG__IS_RENAME_SOURCE) == 0)
 				continue;
 
 			/* calculate similarity for this pair and find best match */
-			if (i == j)
+			if (s == t)
 				similarity = -1; /* don't measure self-similarity here */
 			else if ((error = similarity_measure(
-				&similarity, diff, &opts, sigcache, 2 * j, 2 * i + 1)) < 0)
+				&similarity, diff, &opts, sigcache, 2 * s, 2 * t + 1)) < 0)
 				goto cleanup;
 
-			/* if this pairing is better for the src and the tgt, keep it */
-			if (similarity > 0 &&
-				match_tgts[i].similarity < (uint32_t)similarity &&
-				match_srcs[j].similarity < (uint32_t)similarity)
+			if (similarity < 0)
+				continue;
+
+			/* is this a better rename? */
+			if (tgt2src[t].similarity < (uint32_t)similarity &&
+				src2tgt[s].similarity < (uint32_t)similarity)
 			{
-				if (match_tgts[i].similarity > 0) {
-					match_tgts[match_srcs[j].idx].similarity = 0;
-					match_srcs[match_tgts[i].idx].similarity = 0;
-					++num_bumped;
+				/* eject old mapping */
+				if (src2tgt[s].similarity > 0) {
+					tgt2src[src2tgt[s].idx].similarity = 0;
+					num_bumped++;
+				}
+				if (tgt2src[t].similarity > 0) {
+					src2tgt[tgt2src[t].idx].similarity = 0;
+					num_bumped++;
 				}
 
-				match_tgts[i].similarity = (uint32_t)similarity;
-				match_tgts[i].idx = (uint32_t)j;
+				/* write new mapping */
+				tgt2src[t].idx = s;
+				tgt2src[t].similarity = (uint32_t)similarity;
+				src2tgt[s].idx = t;
+				src2tgt[s].similarity = (uint32_t)similarity;
+			}
 
-				match_srcs[j].similarity = (uint32_t)similarity;
-				match_srcs[j].idx = (uint32_t)i;
+			/* keep best absolute match for copies */
+			if (tgt2src_copy != NULL &&
+				tgt2src_copy[t].similarity < (uint32_t)similarity)
+			{
+				tgt2src_copy[t].idx = s;
+				tgt2src_copy[t].similarity = (uint32_t)similarity;
 			}
 
 			if (++tried_srcs >= num_srcs)
 				break;
 
-			/* cap on maximum targets we'll examine (per "to" file) */
+			/* cap on maximum targets we'll examine (per "tgt" file) */
 			if (tried_srcs > opts.rename_limit)
 				break;
 		}
@@ -801,18 +894,21 @@ find_best_matches:
 
 	tried_tgts = 0;
 
-	git_vector_foreach(&diff->deltas, i, to) {
+	git_vector_foreach(&diff->deltas, t, tgt) {
 		/* skip things that are not rename targets */
-		if ((to->flags & GIT_DIFF_FLAG__IS_RENAME_TARGET) == 0)
+		if ((tgt->flags & GIT_DIFF_FLAG__IS_RENAME_TARGET) == 0)
 			continue;
 
 		/* check if this delta was the target of a similarity */
-		best_match = &match_tgts[i];
-		if (!best_match->similarity)
+		if (tgt2src[t].similarity)
+			best_match = &tgt2src[t];
+		else if (tgt2src_copy && tgt2src_copy[t].similarity)
+			best_match = &tgt2src_copy[t];
+		else
 			continue;
 
-		j = best_match->idx;
-		from = GIT_VECTOR_GET(&diff->deltas, j);
+		s = best_match->idx;
+		src = GIT_VECTOR_GET(&diff->deltas, s);
 
 		/* possible scenarios:
 		 * 1. from DELETE to ADD/UNTRACK/IGNORE = RENAME
@@ -822,101 +918,112 @@ find_best_matches:
 		 * 5. from OTHER to ADD/UNTRACK/IGNORE = OTHER + COPY
 		 */
 
-		if (from->status == GIT_DELTA_DELETED) {
+		if (src->status == GIT_DELTA_DELETED) {
 
-			if (delta_is_new_only(to)) {
+			if (delta_is_new_only(tgt)) {
 
 				if (best_match->similarity < opts.rename_threshold)
 					continue;
 
-				delta_make_rename(to, from, best_match->similarity);
+				delta_make_rename(tgt, src, best_match->similarity);
 
-				from->flags |= GIT_DIFF_FLAG__TO_DELETE;
+				src->flags |= GIT_DIFF_FLAG__TO_DELETE;
 				num_rewrites++;
 			} else {
-				assert(delta_is_split(to));
+				assert(delta_is_split(tgt));
 
 				if (best_match->similarity < opts.rename_from_rewrite_threshold)
 					continue;
 
-				memcpy(&swap, &to->old_file, sizeof(swap));
+				memcpy(&swap, &tgt->old_file, sizeof(swap));
 
-				delta_make_rename(to, from, best_match->similarity);
+				delta_make_rename(tgt, src, best_match->similarity);
 				num_rewrites--;
 
-				from->status = GIT_DELTA_DELETED;
-				memcpy(&from->old_file, &swap, sizeof(from->old_file));
-				memset(&from->new_file, 0, sizeof(from->new_file));
-				from->new_file.path = from->old_file.path;
-				from->new_file.flags |= GIT_DIFF_FLAG_VALID_OID;
+				src->status = GIT_DELTA_DELETED;
+				memcpy(&src->old_file, &swap, sizeof(src->old_file));
+				memset(&src->new_file, 0, sizeof(src->new_file));
+				src->new_file.path = src->old_file.path;
+				src->new_file.flags |= GIT_DIFF_FLAG_VALID_OID;
 
 				num_updates++;
+
+				if (src2tgt[t].similarity > 0 && src2tgt[t].idx > t) {
+					/* what used to be at src t is now at src s */
+					tgt2src[src2tgt[t].idx].idx = (uint32_t)s;
+				}
 			}
 		}
 
-		else if (delta_is_split(from)) {
+		else if (delta_is_split(src)) {
 
-			if (delta_is_new_only(to)) {
+			if (delta_is_new_only(tgt)) {
 
 				if (best_match->similarity < opts.rename_threshold)
 					continue;
 
-				delta_make_rename(to, from, best_match->similarity);
+				delta_make_rename(tgt, src, best_match->similarity);
 
-				from->status = (diff->new_src == GIT_ITERATOR_TYPE_WORKDIR) ?
+				src->status = (diff->new_src == GIT_ITERATOR_TYPE_WORKDIR) ?
 					GIT_DELTA_UNTRACKED : GIT_DELTA_ADDED;
-				memset(&from->old_file, 0, sizeof(from->old_file));
-				from->old_file.path = from->new_file.path;
-				from->old_file.flags |= GIT_DIFF_FLAG_VALID_OID;
+				memset(&src->old_file, 0, sizeof(src->old_file));
+				src->old_file.path = src->new_file.path;
+				src->old_file.flags |= GIT_DIFF_FLAG_VALID_OID;
 
-				from->flags &= ~GIT_DIFF_FLAG__TO_SPLIT;
+				src->flags &= ~GIT_DIFF_FLAG__TO_SPLIT;
 				num_rewrites--;
 
 				num_updates++;
 			} else {
-				assert(delta_is_split(from));
+				assert(delta_is_split(src));
 
 				if (best_match->similarity < opts.rename_from_rewrite_threshold)
 					continue;
 
-				memcpy(&swap, &to->old_file, sizeof(swap));
+				memcpy(&swap, &tgt->old_file, sizeof(swap));
 
-				delta_make_rename(to, from, best_match->similarity);
+				delta_make_rename(tgt, src, best_match->similarity);
 				num_rewrites--;
 				num_updates++;
 
-				memcpy(&from->old_file, &swap, sizeof(from->old_file));
+				memcpy(&src->old_file, &swap, sizeof(src->old_file));
 
 				/* if we've just swapped the new element into the correct
 				 * place, clear the SPLIT flag
 				 */
-				if (match_tgts[j].idx == i &&
-					match_tgts[j].similarity >
+				if (tgt2src[s].idx == t &&
+					tgt2src[s].similarity >
 					opts.rename_from_rewrite_threshold) {
-
-					from->status     = GIT_DELTA_RENAMED;
-					from->similarity = match_tgts[j].similarity;
-					match_tgts[j].similarity = 0;
-					from->flags &= ~GIT_DIFF_FLAG__TO_SPLIT;
+					src->status     = GIT_DELTA_RENAMED;
+					src->similarity = tgt2src[s].similarity;
+					tgt2src[s].similarity = 0;
+					src->flags &= ~GIT_DIFF_FLAG__TO_SPLIT;
 					num_rewrites--;
 				}
 				/* otherwise, if we just overwrote a source, update mapping */
-				else if (j > i && match_srcs[i].similarity > 0) {
-					match_tgts[match_srcs[i].idx].idx = (uint32_t)j;
+				else if (src2tgt[t].similarity > 0 && src2tgt[t].idx > t) {
+					/* what used to be at src t is now at src s */
+					tgt2src[src2tgt[t].idx].idx = (uint32_t)s;
 				}
 
 				num_updates++;
 			}
 		}
 
-		else if (delta_is_new_only(to)) {
-			if (!FLAG_SET(&opts, GIT_DIFF_FIND_COPIES) ||
-				best_match->similarity < opts.copy_threshold)
+		else if (delta_is_new_only(tgt)) {
+			if (!FLAG_SET(&opts, GIT_DIFF_FIND_COPIES))
 				continue;
 
-			to->status     = GIT_DELTA_COPIED;
-			to->similarity = best_match->similarity;
-			memcpy(&to->old_file, &from->old_file, sizeof(to->old_file));
+			if (tgt2src_copy[t].similarity < opts.copy_threshold)
+				continue;
+
+			/* always use best possible source for copy */
+			best_match = &tgt2src_copy[t];
+			src = GIT_VECTOR_GET(&diff->deltas, best_match->idx);
+
+			tgt->status     = GIT_DELTA_COPIED;
+			tgt->similarity = best_match->similarity;
+			memcpy(&tgt->old_file, &src->old_file, sizeof(tgt->old_file));
 
 			num_updates++;
 		}
@@ -932,12 +1039,13 @@ find_best_matches:
 			FLAG_SET(&opts, GIT_DIFF_BREAK_REWRITES));
 
 cleanup:
-	git__free(match_srcs);
-	git__free(match_tgts);
+	git__free(tgt2src);
+	git__free(src2tgt);
+	git__free(tgt2src_copy);
 
-	for (i = 0; i < sigcache_size; ++i) {
-		if (sigcache[i] != NULL)
-			opts.metric->free_signature(sigcache[i], opts.metric->payload);
+	for (t = 0; t < num_deltas * 2; ++t) {
+		if (sigcache[t] != NULL)
+			opts.metric->free_signature(sigcache[t], opts.metric->payload);
 	}
 	git__free(sigcache);
 
diff --git a/src/hashsig.c b/src/hashsig.c
index ab8d8b3..109f966 100644
--- a/src/hashsig.c
+++ b/src/hashsig.c
@@ -13,12 +13,15 @@ typedef uint64_t hashsig_state;
 
 #define HASHSIG_SCALE 100
 
-#define HASHSIG_HASH_WINDOW 32
-#define HASHSIG_HASH_START	0
+#define HASHSIG_MAX_RUN 80
+#define HASHSIG_HASH_START	0x012345678ABCDEF0LL
 #define HASHSIG_HASH_SHIFT  5
-#define HASHSIG_HASH_MASK   0x7FFFFFFF
+
+#define HASHSIG_HASH_MIX(S,CH) \
+	(S) = ((S) << HASHSIG_HASH_SHIFT) - (S) + (hashsig_state)(CH)
 
 #define HASHSIG_HEAP_SIZE ((1 << 7) - 1)
+#define HASHSIG_HEAP_MIN_SIZE 4
 
 typedef int (*hashsig_cmp)(const void *a, const void *b, void *);
 
@@ -28,14 +31,6 @@ typedef struct {
 	hashsig_t values[HASHSIG_HEAP_SIZE];
 } hashsig_heap;
 
-typedef struct {
-	hashsig_state state, shift_n;
-	char window[HASHSIG_HASH_WINDOW];
-	int win_len, win_pos, saw_lf;
-} hashsig_in_progress;
-
-#define HASHSIG_IN_PROGRESS_INIT { HASHSIG_HASH_START, 1, {0}, 0, 0, 1 }
-
 struct git_hashsig {
 	hashsig_heap mins;
 	hashsig_heap maxs;
@@ -43,8 +38,8 @@ struct git_hashsig {
 	int considered;
 };
 
-#define HEAP_LCHILD_OF(I) (((I)*2)+1)
-#define HEAP_RCHILD_OF(I) (((I)*2)+2)
+#define HEAP_LCHILD_OF(I) (((I)<<1)+1)
+#define HEAP_RCHILD_OF(I) (((I)<<1)+2)
 #define HEAP_PARENT_OF(I) (((I)-1)>>1)
 
 static void hashsig_heap_init(hashsig_heap *h, hashsig_cmp cmp)
@@ -115,134 +110,109 @@ static void hashsig_heap_sort(hashsig_heap *h)
 
 static void hashsig_heap_insert(hashsig_heap *h, hashsig_t val)
 {
-	/* if heap is full, pop top if new element should replace it */
-	if (h->size == h->asize && h->cmp(&val, &h->values[0], NULL) > 0) {
-		h->size--;
-		h->values[0] = h->values[h->size];
-		hashsig_heap_down(h, 0);
-	}
-
 	/* if heap is not full, insert new element */
 	if (h->size < h->asize) {
 		h->values[h->size++] = val;
 		hashsig_heap_up(h, h->size - 1);
 	}
-}
-
-GIT_INLINE(bool) hashsig_include_char(
-	char ch, git_hashsig_option_t opt, int *saw_lf)
-{
-	if ((opt & GIT_HASHSIG_IGNORE_WHITESPACE) && git__isspace(ch))
-		return false;
-
-	if (opt & GIT_HASHSIG_SMART_WHITESPACE) {
-		if (ch == '\r' || (*saw_lf && git__isspace(ch)))
-			return false;
 
-		*saw_lf = (ch == '\n');
+	/* if heap is full, pop top if new element should replace it */
+	else if (h->cmp(&val, &h->values[0], NULL) > 0) {
+		h->size--;
+		h->values[0] = h->values[h->size];
+		hashsig_heap_down(h, 0);
 	}
 
-	return true;
 }
 
-static void hashsig_initial_window(
-	git_hashsig *sig,
-	const char **data,
-	size_t size,
-	hashsig_in_progress *prog)
-{
-	hashsig_state state, shift_n;
-	int win_len;
-	const char *scan, *end;
-
-	/* init until we have processed at least HASHSIG_HASH_WINDOW data */
-
-	if (prog->win_len >= HASHSIG_HASH_WINDOW)
-		return;
-
-	state   = prog->state;
-	win_len = prog->win_len;
-	shift_n = prog->shift_n;
-
-	scan = *data;
-	end  = scan + size;
-
-	while (scan < end && win_len < HASHSIG_HASH_WINDOW) {
-		char ch = *scan++;
-
-		if (!hashsig_include_char(ch, sig->opt, &prog->saw_lf))
-			continue;
-
-		state = (state * HASHSIG_HASH_SHIFT + ch) & HASHSIG_HASH_MASK;
-
-		if (!win_len)
-			shift_n = 1;
-		else
-			shift_n = (shift_n * HASHSIG_HASH_SHIFT) & HASHSIG_HASH_MASK;
-
-		prog->window[win_len++] = ch;
-	}
-
-	/* insert initial hash if we just finished */
+typedef struct {
+	int use_ignores;
+	uint8_t ignore_ch[256];
+} hashsig_in_progress;
 
-	if (win_len == HASHSIG_HASH_WINDOW) {
-		hashsig_heap_insert(&sig->mins, (hashsig_t)state);
-		hashsig_heap_insert(&sig->maxs, (hashsig_t)state);
-		sig->considered = 1;
+static void hashsig_in_progress_init(
+	hashsig_in_progress *prog, git_hashsig *sig)
+{
+	int i;
+
+	switch (sig->opt) {
+	case GIT_HASHSIG_IGNORE_WHITESPACE:
+		for (i = 0; i < 256; ++i)
+			prog->ignore_ch[i] = git__isspace_nonlf(i);
+		prog->use_ignores = 1;
+		break;
+	case GIT_HASHSIG_SMART_WHITESPACE:
+		for (i = 0; i < 256; ++i)
+			prog->ignore_ch[i] = git__isspace(i);
+		prog->use_ignores = 1;
+		break;
+	default:
+		memset(prog, 0, sizeof(*prog));
+		break;
 	}
-
-	prog->state   = state;
-	prog->win_len = win_len;
-	prog->shift_n = shift_n;
-
-	*data = scan;
 }
 
+#define HASHSIG_IN_PROGRESS_INIT { 1 }
+
 static int hashsig_add_hashes(
 	git_hashsig *sig,
-	const char *data,
+	const uint8_t *data,
 	size_t size,
 	hashsig_in_progress *prog)
 {
-	const char *scan = data, *end = data + size;
-	hashsig_state state, shift_n, rmv;
-
-	if (prog->win_len < HASHSIG_HASH_WINDOW)
-		hashsig_initial_window(sig, &scan, size, prog);
-
-	state   = prog->state;
-	shift_n = prog->shift_n;
-
-	/* advance window, adding new chars and removing old */
-
-	for (; scan < end; ++scan) {
-		char ch = *scan;
-
-		if (!hashsig_include_char(ch, sig->opt, &prog->saw_lf))
-			continue;
-
-		rmv = shift_n * prog->window[prog->win_pos];
+	const uint8_t *scan = data, *end = data + size;
+	hashsig_state state = HASHSIG_HASH_START;
+	int use_ignores = prog->use_ignores, len;
+	uint8_t ch;
+
+	while (scan < end) {
+		state = HASHSIG_HASH_START;
+
+		for (len = 0; scan < end && len < HASHSIG_MAX_RUN; ) {
+			ch = *scan;
+
+			if (use_ignores)
+				for (; scan < end && git__isspace_nonlf(ch); ch = *scan)
+					++scan;
+			else if (sig->opt != GIT_HASHSIG_NORMAL)
+				for (; scan < end && ch == '\r'; ch = *scan)
+					++scan;
+
+			/* peek at next character to decide what to do next */
+			if (sig->opt == GIT_HASHSIG_SMART_WHITESPACE)
+				use_ignores = (ch == '\n');
+
+			if (scan >= end)
+				break;
+			++scan;
+
+			/* check run terminator */
+			if (ch == '\n' || ch == '\0')
+				break;
+
+			++len;
+			HASHSIG_HASH_MIX(state, ch);
+		}
 
-		state = (state - rmv) & HASHSIG_HASH_MASK;
-		state = (state * HASHSIG_HASH_SHIFT) & HASHSIG_HASH_MASK;
-		state = (state + ch) & HASHSIG_HASH_MASK;
+		if (len > 0) {
+			hashsig_heap_insert(&sig->mins, (hashsig_t)state);
+			hashsig_heap_insert(&sig->maxs, (hashsig_t)state);
 
-		hashsig_heap_insert(&sig->mins, (hashsig_t)state);
-		hashsig_heap_insert(&sig->maxs, (hashsig_t)state);
-		sig->considered++;
+			sig->considered++;
 
-		prog->window[prog->win_pos] = ch;
-		prog->win_pos = (prog->win_pos + 1) % HASHSIG_HASH_WINDOW;
+			while (scan < end && (*scan == '\n' || !*scan))
+				++scan;
+		}
 	}
 
-	prog->state = state;
+	prog->use_ignores = use_ignores;
 
 	return 0;
 }
 
 static int hashsig_finalize_hashes(git_hashsig *sig)
 {
-	if (sig->mins.size < HASHSIG_HEAP_SIZE) {
+	if (sig->mins.size < HASHSIG_HEAP_MIN_SIZE) {
 		giterr_set(GITERR_INVALID,
 			"File too small for similarity signature calculation");
 		return GIT_EBUFS;
@@ -274,11 +244,13 @@ int git_hashsig_create(
 	git_hashsig_option_t opts)
 {
 	int error;
-	hashsig_in_progress prog = HASHSIG_IN_PROGRESS_INIT;
+	hashsig_in_progress prog;
 	git_hashsig *sig = hashsig_alloc(opts);
 	GITERR_CHECK_ALLOC(sig);
 
-	error = hashsig_add_hashes(sig, buf, buflen, &prog);
+	hashsig_in_progress_init(&prog, sig);
+
+	error = hashsig_add_hashes(sig, (const uint8_t *)buf, buflen, &prog);
 
 	if (!error)
 		error = hashsig_finalize_hashes(sig);
@@ -296,10 +268,10 @@ int git_hashsig_create_fromfile(
 	const char *path,
 	git_hashsig_option_t opts)
 {
-	char buf[4096];
+	uint8_t buf[0x1000];
 	ssize_t buflen = 0;
 	int error = 0, fd;
-	hashsig_in_progress prog = HASHSIG_IN_PROGRESS_INIT;
+	hashsig_in_progress prog;
 	git_hashsig *sig = hashsig_alloc(opts);
 	GITERR_CHECK_ALLOC(sig);
 
@@ -308,6 +280,8 @@ int git_hashsig_create_fromfile(
 		return fd;
 	}
 
+	hashsig_in_progress_init(&prog, sig);
+
 	while (!error) {
 		if ((buflen = p_read(fd, buf, sizeof(buf))) <= 0) {
 			if ((error = (int)buflen) < 0)
@@ -362,6 +336,12 @@ static int hashsig_heap_compare(const hashsig_heap *a, const hashsig_heap *b)
 
 int git_hashsig_compare(const git_hashsig *a, const git_hashsig *b)
 {
-	return (hashsig_heap_compare(&a->mins, &b->mins) +
-			hashsig_heap_compare(&a->maxs, &b->maxs)) / 2;
+	/* if we have fewer than the maximum number of elements, then just use
+	 * one array since the two arrays will be the same
+	 */
+	if (a->mins.size < HASHSIG_HEAP_SIZE)
+		return hashsig_heap_compare(&a->mins, &b->mins);
+	else
+		return (hashsig_heap_compare(&a->mins, &b->mins) +
+				hashsig_heap_compare(&a->maxs, &b->maxs)) / 2;
 }
diff --git a/src/index.c b/src/index.c
index 0610eb5..cbdd43b 100644
--- a/src/index.c
+++ b/src/index.c
@@ -16,6 +16,7 @@
 #include "iterator.h"
 #include "pathspec.h"
 #include "ignore.h"
+#include "blob.h"
 
 #include "git2/odb.h"
 #include "git2/oid.h"
@@ -604,42 +605,23 @@ int git_index_entry__cmp_icase(const void *a, const void *b)
 	return strcasecmp(entry_a->path, entry_b->path);
 }
 
-static int index_entry_init(git_index_entry **entry_out, git_index *index, const char *rel_path)
+static int index_entry_init(
+	git_index_entry **entry_out, git_index *index, const char *rel_path)
 {
+	int error = 0;
 	git_index_entry *entry = NULL;
 	struct stat st;
 	git_oid oid;
-	const char *workdir;
-	git_buf full_path = GIT_BUF_INIT;
-	int error;
 
 	if (INDEX_OWNER(index) == NULL)
 		return create_index_error(-1,
 			"Could not initialize index entry. "
 			"Index is not backed up by an existing repository.");
 
-	workdir = git_repository_workdir(INDEX_OWNER(index));
-
-	if (!workdir)
-		return create_index_error(GIT_EBAREREPO,
-			"Could not initialize index entry. Repository is bare");
-
-	if ((error = git_buf_joinpath(&full_path, workdir, rel_path)) < 0)
-		return error;
-
-	if ((error = git_path_lstat(full_path.ptr, &st)) < 0) {
-		git_buf_free(&full_path);
-		return error;
-	}
-
-	git_buf_free(&full_path); /* done with full path */
-
-	/* There is no need to validate the rel_path here, since it will be
-	 * immediately validated by the call to git_blob_create_fromfile.
-	 */
-
-	/* write the blob to disk and get the oid */
-	if ((error = git_blob_create_fromworkdir(&oid, INDEX_OWNER(index), rel_path)) < 0)
+	/* write the blob to disk and get the oid and stat info */
+	error = git_blob__create_from_paths(
+		&oid, &st, INDEX_OWNER(index), NULL, rel_path, 0, true);
+	if (error < 0)
 		return error;
 
 	entry = git__calloc(1, sizeof(git_index_entry));
diff --git a/src/util.h b/src/util.h
index a97c9bf..ed96247 100644
--- a/src/util.h
+++ b/src/util.h
@@ -294,6 +294,11 @@ GIT_INLINE(bool) git__isspace(int c)
 	return (c == ' ' || c == '\t' || c == '\n' || c == '\f' || c == '\r' || c == '\v' || c == 0x85 /* Unicode CR+LF */);
 }
 
+GIT_INLINE(bool) git__isspace_nonlf(int c)
+{
+	return (c == ' ' || c == '\t' || c == '\f' || c == '\r' || c == '\v' || c == 0x85 /* Unicode CR+LF */);
+}
+
 GIT_INLINE(bool) git__iswildcard(int c)
 {
 	return (c == '*' || c == '?' || c == '[');
diff --git a/tests-clar/clar_libgit2.h b/tests-clar/clar_libgit2.h
index 5371b28..8c8357e 100644
--- a/tests-clar/clar_libgit2.h
+++ b/tests-clar/clar_libgit2.h
@@ -34,6 +34,20 @@ void cl_git_report_failure(int, const char *, int, const char *);
 
 #define cl_assert_equal_sz(sz1,sz2) cl_assert_equal_i((int)sz1, (int)(sz2))
 
+GIT_INLINE(void) clar__assert_in_range(
+	int lo, int val, int hi,
+	const char *file, int line, const char *err, int should_abort)
+{
+	if (lo > val || hi < val) {
+		char buf[128];
+		snprintf(buf, sizeof(buf), "%d not in [%d,%d]", val, lo, hi);
+		clar__fail(file, line, err, buf, should_abort);
+	}
+}
+
+#define cl_assert_in_range(L,V,H) \
+	clar__assert_in_range((L),(V),(H),__FILE__,__LINE__,"Range check: " #V " in [" #L "," #H "]", 1)
+
 /*
  * Some utility macros for building long strings
  */
diff --git a/tests-clar/core/buffer.c b/tests-clar/core/buffer.c
index 3d8221e..9d9628c 100644
--- a/tests-clar/core/buffer.c
+++ b/tests-clar/core/buffer.c
@@ -734,10 +734,11 @@ void test_core_buffer__classify_with_utf8(void)
 }
 
 #define SIMILARITY_TEST_DATA_1 \
-	"test data\nright here\ninline\ntada\nneeds more data\nlots of data\n" \
-	"is this enough?\nthere has to be enough data to fill the hash array!\n" \
-	"Apparently 191 bytes is the minimum amount of data needed.\nHere goes!\n" \
-	"Let's make sure we've got plenty to go with here.\n   smile   \n"
+	"000\n001\n002\n003\n004\n005\n006\n007\n008\n009\n" \
+	"010\n011\n012\n013\n014\n015\n016\n017\n018\n019\n" \
+	"020\n021\n022\n023\n024\n025\n026\n027\n028\n029\n" \
+	"030\n031\n032\n033\n034\n035\n036\n037\n038\n039\n" \
+	"040\n041\n042\n043\n044\n045\n046\n047\n048\n049\n"
 
 void test_core_buffer__similarity_metric(void)
 {
@@ -761,15 +762,17 @@ void test_core_buffer__similarity_metric(void)
 	cl_git_pass(git_buf_sets(&buf, SIMILARITY_TEST_DATA_1));
 	cl_git_pass(git_hashsig_create(&a, buf.ptr, buf.size, GIT_HASHSIG_NORMAL));
 	cl_git_pass(git_buf_sets(&buf,
-		"Test data\nright here\ninline\ntada\nneeds more data\nlots of data\n"
-		"is this enough?\nthere has to be enough data to fill the hash array!\n"
-		"Apparently 191 bytes is the minimum amount of data needed.\nHere goes!\n"
-		 "Let's make sure we've got plenty to go with here.\n   smile   \n"));
+		"000\n001\n002\n003\n004\n005\n006\n007\n008\n009\n" \
+		"010\n011\n012\n013\n014\n015\n016\n017\n018\n019\n" \
+		"x020x\n021\n022\n023\n024\n025\n026\n027\n028\n029\n" \
+		"030\n031\n032\n033\n034\n035\n036\n037\n038\n039\n" \
+		"040\n041\n042\n043\n044\n045\n046\n047\n048\n049\n"
+		));
 	cl_git_pass(git_hashsig_create(&b, buf.ptr, buf.size, GIT_HASHSIG_NORMAL));
 
 	sim = git_hashsig_compare(a, b);
 
-	cl_assert(95 < sim && sim < 100); /* expect >95% similarity */
+	cl_assert_in_range(95, sim, 100); /* expect >95% similarity */
 
 	git_hashsig_free(a);
 	git_hashsig_free(b);
@@ -779,12 +782,13 @@ void test_core_buffer__similarity_metric(void)
 	cl_git_pass(git_buf_sets(&buf, SIMILARITY_TEST_DATA_1));
 	cl_git_pass(git_hashsig_create(&a, buf.ptr, buf.size, GIT_HASHSIG_NORMAL));
 	cl_git_pass(git_buf_sets(&buf, SIMILARITY_TEST_DATA_1
-		"and if I add some more, it should still be pretty similar, yes?\n"));
+		"050\n051\n052\n053\n054\n055\n056\n057\n058\n059\n"));
 	cl_git_pass(git_hashsig_create(&b, buf.ptr, buf.size, GIT_HASHSIG_NORMAL));
 
 	sim = git_hashsig_compare(a, b);
+	/* 20% lines added ~= 10% lines changed */
 
-	cl_assert(70 < sim && sim < 80); /* expect in the 70-80% similarity range */
+	cl_assert_in_range(85, sim, 95); /* expect similarity around 90% */
 
 	git_hashsig_free(a);
 	git_hashsig_free(b);
@@ -794,15 +798,19 @@ void test_core_buffer__similarity_metric(void)
 	cl_git_pass(git_buf_sets(&buf, SIMILARITY_TEST_DATA_1));
 	cl_git_pass(git_hashsig_create(&a, buf.ptr, buf.size, GIT_HASHSIG_NORMAL));
 	cl_git_pass(git_buf_sets(&buf,
-		"test data\nright here\ninline\ntada\nneeds more data\nlots of data\n"
-		"is this enough?\nthere has to be enough data to fill the hash array!\n"
-		"okay, that's half the original\nwhat else can we add?\nmore data\n"
-		 "one more line will complete this\nshort\nlines\ndon't\nmatter\n"));
+		"000\n001\n002\n003\n004\n005\n006\n007\n008\n009\n" \
+		"010\n011\n012\n013\n014\n015\n016\n017\n018\n019\n" \
+		"020x\n021\n022\n023\n024\n" \
+		"x25\nx26\nx27\nx28\nx29\n" \
+		"x30\nx31\nx32\nx33\nx34\nx35\nx36\nx37\nx38\nx39\n" \
+		"x40\nx41\nx42\nx43\nx44\nx45\nx46\nx47\nx48\nx49\n"
+		));
 	cl_git_pass(git_hashsig_create(&b, buf.ptr, buf.size, GIT_HASHSIG_NORMAL));
 
 	sim = git_hashsig_compare(a, b);
+	/* 50% lines changed */
 
-	cl_assert(40 < sim && sim < 60); /* expect in the 40-60% similarity range */
+	cl_assert_in_range(40, sim, 60); /* expect in the 40-60% similarity range */
 
 	git_hashsig_free(a);
 	git_hashsig_free(b);
@@ -891,7 +899,7 @@ void test_core_buffer__similarity_metric_whitespace(void)
 					if (i == j)
 						cl_assert_equal_i(100, sim);
 					else
-						cl_assert(sim < 30); /* expect pretty different */
+						cl_assert_in_range(0, sim, 30); /* pretty different */
 				} else {
 					cl_assert_equal_i(100, sim);
 				}
diff --git a/tests-clar/diff/rename.c b/tests-clar/diff/rename.c
index 9efd928..5a35495 100644
--- a/tests-clar/diff/rename.c
+++ b/tests-clar/diff/rename.c
@@ -236,6 +236,8 @@ void test_diff_rename__not_exact_match(void)
 		&diff, g_repo, old_tree, new_tree, &diffopts));
 
 	opts.flags = GIT_DIFF_FIND_ALL;
+	opts.break_rewrite_threshold = 70;
+
 	cl_git_pass(git_diff_find_similar(diff, &opts));
 
 	memset(&exp, 0, sizeof(exp));
@@ -312,8 +314,8 @@ void test_diff_rename__not_exact_match(void)
 
 	/* the default match algorithm is going to find the internal
 	 * whitespace differences in the lines of sixserving.txt to be
-	 * significant enough that this will decide to split it into
-	 * an ADD and a DELETE
+	 * significant enough that this will decide to split it into an ADD
+	 * and a DELETE
 	 */
 
 	memset(&exp, 0, sizeof(exp));
@@ -480,6 +482,7 @@ void test_diff_rename__working_directory_changes(void)
 	cl_git_pass(git_diff_tree_to_workdir(&diff, g_repo, tree, &diffopts));
 
 	opts.flags = GIT_DIFF_FIND_ALL | GIT_DIFF_FIND_DONT_IGNORE_WHITESPACE;
+	opts.rename_threshold = 70;
 	cl_git_pass(git_diff_find_similar(diff, &opts));
 
 	memset(&exp, 0, sizeof(exp));
@@ -868,6 +871,8 @@ void test_diff_rename__from_deleted_to_split(void)
 struct rename_expected
 {
 	size_t len;
+
+	unsigned int *status;
 	const char **sources;
 	const char **targets;
 
@@ -882,7 +887,7 @@ int test_names_expected(const git_diff_delta *delta, float progress, void *p)
 
 	cl_assert(expected->idx < expected->len);
 
-	cl_assert_equal_i(delta->status, GIT_DELTA_RENAMED);
+	cl_assert_equal_i(delta->status, expected->status[expected->idx]);
 
 	cl_assert(git__strcmp(expected->sources[expected->idx],
 		delta->old_file.path) == 0);
@@ -904,9 +909,10 @@ void test_diff_rename__rejected_match_can_match_others(void)
 	git_diff_options diffopts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_find_options findopts = GIT_DIFF_FIND_OPTIONS_INIT;
 	git_buf one = GIT_BUF_INIT, two = GIT_BUF_INIT;
+	unsigned int status[] = { GIT_DELTA_RENAMED, GIT_DELTA_RENAMED };
 	const char *sources[] = { "Class1.cs", "Class2.cs" };
 	const char *targets[] = { "ClassA.cs", "ClassB.cs" };
-	struct rename_expected expect = { 2, sources, targets };
+	struct rename_expected expect = { 2, status, sources, targets };
 	char *ptr;
 
 	opts.checkout_strategy = GIT_CHECKOUT_FORCE;
@@ -988,9 +994,10 @@ void test_diff_rename__rejected_match_can_match_others_two(void)
 	git_diff_list *diff;
 	git_diff_options diffopts = GIT_DIFF_OPTIONS_INIT;
 	git_diff_find_options findopts = GIT_DIFF_FIND_OPTIONS_INIT;
+	unsigned int status[] = { GIT_DELTA_RENAMED, GIT_DELTA_RENAMED };
 	const char *sources[] = { "a.txt", "b.txt" };
 	const char *targets[] = { "c.txt", "d.txt" };
-	struct rename_expected expect = { 2, sources, targets };
+	struct rename_expected expect = { 2, status, sources, targets };
 
 	opts.checkout_strategy = GIT_CHECKOUT_FORCE;
 
@@ -1033,6 +1040,112 @@ void test_diff_rename__rejected_match_can_match_others_two(void)
 	git_reference_free(selfsimilar);
 }
 
+void test_diff_rename__rejected_match_can_match_others_three(void)
+{
+	git_reference *head, *selfsimilar;
+	git_index *index;
+	git_tree *tree;
+	git_checkout_opts opts = GIT_CHECKOUT_OPTS_INIT;
+	git_diff_list *diff;
+	git_diff_options diffopts = GIT_DIFF_OPTIONS_INIT;
+	git_diff_find_options findopts = GIT_DIFF_FIND_OPTIONS_INIT;
+
+	/* Both cannot be renames from a.txt */
+	unsigned int status[] = { GIT_DELTA_ADDED, GIT_DELTA_RENAMED };
+	const char *sources[] = { "0001.txt", "a.txt" };
+	const char *targets[] = { "0001.txt", "0002.txt" };
+	struct rename_expected expect = { 2, status, sources, targets };
+
+	opts.checkout_strategy = GIT_CHECKOUT_FORCE;
+
+	cl_git_pass(git_reference_lookup(&head, g_repo, "HEAD"));
+	cl_git_pass(git_reference_symbolic_set_target(
+		&selfsimilar, head, "refs/heads/renames_similar_two"));
+	cl_git_pass(git_checkout_head(g_repo, &opts));
+	cl_git_pass(git_repository_index(&index, g_repo));
+
+	cl_git_pass(p_unlink("renames/a.txt"));
+
+	cl_git_pass(git_index_remove_bypath(index, "a.txt"));
+
+	write_similarity_file_two("renames/0001.txt", 7);
+	write_similarity_file_two("renames/0002.txt", 0);
+
+	cl_git_pass(git_index_add_bypath(index, "0001.txt"));
+	cl_git_pass(git_index_add_bypath(index, "0002.txt"));
+
+	cl_git_pass(git_index_write(index));
+
+	cl_git_pass(
+		git_revparse_single((git_object **)&tree, g_repo, "HEAD^{tree}"));
+
+	cl_git_pass(
+		git_diff_tree_to_index(&diff, g_repo, tree, index, &diffopts));
+
+	cl_git_pass(git_diff_find_similar(diff, &findopts));
+
+	cl_git_pass(
+		git_diff_foreach(diff, test_names_expected, NULL, NULL, &expect));
+
+	cl_assert(expect.idx == expect.len);
+
+	git_diff_list_free(diff);
+	git_tree_free(tree);
+	git_index_free(index);
+	git_reference_free(head);
+	git_reference_free(selfsimilar);
+}
+
+void test_diff_rename__can_rename_from_rewrite(void)
+{
+	git_index *index;
+	git_tree *tree;
+	git_checkout_opts opts = GIT_CHECKOUT_OPTS_INIT;
+	git_diff_list *diff;
+	git_diff_options diffopts = GIT_DIFF_OPTIONS_INIT;
+	git_diff_find_options findopts = GIT_DIFF_FIND_OPTIONS_INIT;
+
+	unsigned int status[] = { GIT_DELTA_RENAMED, GIT_DELTA_RENAMED };
+	const char *sources[] = { "ikeepsix.txt", "songof7cities.txt" };
+	const char *targets[] = { "songof7cities.txt", "this-is-a-rename.txt" };
+	struct rename_expected expect = { 2, status, sources, targets };
+
+	opts.checkout_strategy = GIT_CHECKOUT_FORCE;
+
+	cl_git_pass(git_repository_index(&index, g_repo));
+
+	cl_git_pass(p_rename("renames/songof7cities.txt", "renames/this-is-a-rename.txt"));
+	cl_git_pass(p_rename("renames/ikeepsix.txt", "renames/songof7cities.txt"));
+
+	cl_git_pass(git_index_remove_bypath(index, "ikeepsix.txt"));
+
+	cl_git_pass(git_index_add_bypath(index, "songof7cities.txt"));
+	cl_git_pass(git_index_add_bypath(index, "this-is-a-rename.txt"));
+
+	cl_git_pass(git_index_write(index));
+
+	cl_git_pass(
+		git_revparse_single((git_object **)&tree, g_repo, "HEAD^{tree}"));
+
+	cl_git_pass(
+		git_diff_tree_to_index(&diff, g_repo, tree, index, &diffopts));
+
+	findopts.flags |= GIT_DIFF_FIND_AND_BREAK_REWRITES |
+		GIT_DIFF_FIND_REWRITES |
+		GIT_DIFF_FIND_RENAMES_FROM_REWRITES;
+
+	cl_git_pass(git_diff_find_similar(diff, &findopts));
+
+	cl_git_pass(
+		git_diff_foreach(diff, test_names_expected, NULL, NULL, &expect));
+
+	cl_assert(expect.idx == expect.len);
+
+	git_diff_list_free(diff);
+	git_tree_free(tree);
+	git_index_free(index);
+}
+
 void test_diff_rename__case_changes_are_split(void)
 {
 	git_index *index;
diff --git a/tests-clar/stress/diff.c b/tests-clar/stress/diff.c
new file mode 100644
index 0000000..62ccd5e
--- /dev/null
+++ b/tests-clar/stress/diff.c
@@ -0,0 +1,164 @@
+#include "clar_libgit2.h"
+#include "../diff/diff_helpers.h"
+
+static git_repository *g_repo = NULL;
+
+void test_stress_diff__initialize(void)
+{
+}
+
+void test_stress_diff__cleanup(void)
+{
+	cl_git_sandbox_cleanup();
+}
+
+#define ANOTHER_POEM \
+"OH, glorious are the guarded heights\nWhere guardian souls abide—\nSelf-exiled from our gross delights—\nAbove, beyond, outside:\nAn ampler arc their spirit swings—\nCommands a juster view—\nWe have their word for all these things,\nNo doubt their words are true.\n\nYet we, the bond slaves of our day,\nWhom dirt and danger press—\nCo-heirs of insolence, delay,\nAnd leagued unfaithfulness—\nSuch is our need must seek indeed\nAnd, having found, engage\nThe men who merely do the work\nFor which they draw the wage.\n\nFrom forge and farm and mine and bench,\nDeck, altar, outpost lone—\nMill, school, battalion, counter, trench,\nRail, senate, sheepfold, throne—\nCreation's cry goes up on high\nFrom age to cheated age:\n\"Send us the men who do the work\n\"For which they draw the wage!\"\n"
+
+static void test_with_many(size_t expected_new)
+{
+	git_index *index;
+	git_tree *tree, *new_tree;
+	git_diff_list *diff = NULL;
+	diff_expects exp;
+	git_diff_options diffopts = GIT_DIFF_OPTIONS_INIT;
+	git_diff_find_options opts = GIT_DIFF_FIND_OPTIONS_INIT;
+
+	cl_git_pass(git_repository_index(&index, g_repo));
+	cl_git_pass(
+		git_revparse_single((git_object **)&tree, g_repo, "HEAD^{tree}"));
+
+	cl_git_pass(p_rename("renames/ikeepsix.txt", "renames/ikeepsix2.txt"));
+	cl_git_pass(git_index_remove_bypath(index, "ikeepsix.txt"));
+	cl_git_pass(git_index_add_bypath(index, "ikeepsix2.txt"));
+	cl_git_pass(git_index_write(index));
+
+	cl_git_pass(git_diff_tree_to_index(&diff, g_repo, tree, index, &diffopts));
+
+	memset(&exp, 0, sizeof(exp));
+	cl_git_pass(git_diff_foreach(
+		diff, diff_file_cb, NULL, NULL, &exp));
+	cl_assert_equal_i(1, exp.file_status[GIT_DELTA_DELETED]);
+	cl_assert_equal_i(expected_new + 1, exp.file_status[GIT_DELTA_ADDED]);
+	cl_assert_equal_i(expected_new + 2, exp.files);
+
+	opts.flags = GIT_DIFF_FIND_ALL;
+	cl_git_pass(git_diff_find_similar(diff, &opts));
+
+	memset(&exp, 0, sizeof(exp));
+	cl_git_pass(git_diff_foreach(
+		diff, diff_file_cb, NULL, NULL, &exp));
+	cl_assert_equal_i(1, exp.file_status[GIT_DELTA_RENAMED]);
+	cl_assert_equal_i(expected_new, exp.file_status[GIT_DELTA_ADDED]);
+	cl_assert_equal_i(expected_new + 1, exp.files);
+
+	git_diff_list_free(diff);
+
+	{
+		git_object *parent;
+		git_signature *sig;
+		git_oid tree_id, commit_id;
+		git_reference *ref;
+
+		cl_git_pass(git_index_write_tree(&tree_id, index));
+		cl_git_pass(git_tree_lookup(&new_tree, g_repo, &tree_id));
+
+		cl_git_pass(git_revparse_ext(&parent, &ref, g_repo, "HEAD"));
+		cl_git_pass(git_signature_new(
+			&sig, "Sm Test", "sm@tester.test", 1372350000, 480));
+
+		cl_git_pass(git_commit_create_v(
+			&commit_id, g_repo, git_reference_name(ref), sig, sig,
+			NULL, "yoyoyo", new_tree, 1, parent));
+
+		git_object_free(parent);
+		git_reference_free(ref);
+		git_signature_free(sig);
+	}
+
+	cl_git_pass(git_diff_tree_to_tree(
+		&diff, g_repo, tree, new_tree, &diffopts));
+
+	memset(&exp, 0, sizeof(exp));
+	cl_git_pass(git_diff_foreach(
+		diff, diff_file_cb, NULL, NULL, &exp));
+	cl_assert_equal_i(1, exp.file_status[GIT_DELTA_DELETED]);
+	cl_assert_equal_i(expected_new + 1, exp.file_status[GIT_DELTA_ADDED]);
+	cl_assert_equal_i(expected_new + 2, exp.files);
+
+	opts.flags = GIT_DIFF_FIND_ALL;
+	cl_git_pass(git_diff_find_similar(diff, &opts));
+
+	memset(&exp, 0, sizeof(exp));
+	cl_git_pass(git_diff_foreach(
+		diff, diff_file_cb, NULL, NULL, &exp));
+	cl_assert_equal_i(1, exp.file_status[GIT_DELTA_RENAMED]);
+	cl_assert_equal_i(expected_new, exp.file_status[GIT_DELTA_ADDED]);
+	cl_assert_equal_i(expected_new + 1, exp.files);
+
+	git_diff_list_free(diff);
+
+	git_tree_free(new_tree);
+	git_tree_free(tree);
+	git_index_free(index);
+}
+
+void test_stress_diff__rename_big_files(void)
+{
+	git_index *index;
+	char tmp[64];
+	int i, j;
+	git_buf b = GIT_BUF_INIT;
+
+	g_repo = cl_git_sandbox_init("renames");
+
+	cl_git_pass(git_repository_index(&index, g_repo));
+
+	for (i = 0; i < 100; i += 1) {
+		snprintf(tmp, sizeof(tmp), "renames/newfile%03d", i);
+		for (j = i * 256; j > 0; --j)
+			git_buf_printf(&b, "more content %d\n", i);
+		cl_git_mkfile(tmp, b.ptr);
+	}
+
+	for (i = 0; i < 100; i += 1) {
+		snprintf(tmp, sizeof(tmp), "renames/newfile%03d", i);
+		cl_git_pass(git_index_add_bypath(index, tmp + strlen("renames/")));
+	}
+
+	git_buf_free(&b);
+	git_index_free(index);
+
+	test_with_many(100);
+}
+
+void test_stress_diff__rename_many_files(void)
+{
+	git_index *index;
+	char tmp[64];
+	int i;
+	git_buf b = GIT_BUF_INIT;
+
+	g_repo = cl_git_sandbox_init("renames");
+
+	cl_git_pass(git_repository_index(&index, g_repo));
+
+	git_buf_printf(&b, "%08d\n" ANOTHER_POEM "%08d\n" ANOTHER_POEM ANOTHER_POEM, 0, 0);
+
+	for (i = 0; i < 2500; i += 1) {
+		snprintf(tmp, sizeof(tmp), "renames/newfile%03d", i);
+		snprintf(b.ptr, 9, "%08d", i);
+		b.ptr[8] = '\n';
+		cl_git_mkfile(tmp, b.ptr);
+	}
+	git_buf_free(&b);
+
+	for (i = 0; i < 2500; i += 1) {
+		snprintf(tmp, sizeof(tmp), "renames/newfile%03d", i);
+		cl_git_pass(git_index_add_bypath(index, tmp + strlen("renames/")));
+	}
+
+	git_index_free(index);
+
+	test_with_many(2500);
+}