Commit a8efc2f7897b439fdf2144329d35fea820498dc7
2019-10-26T14:57:05
Fix FFI_STDCALL ABI (#514) Even for a stdcall function, the stack alignment is still the responsibility of the caller. Remember the original, not stack-aligned argument size, but align when setting up a stack frame. In ffi_closure_inner, return the true argument size, so that ffi_[go_]closure_STDCALL doesn't adjust too much.
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diff --git a/src/x86/ffi.c b/src/x86/ffi.c
index 883cc4a..9a59218 100644
--- a/src/x86/ffi.c
+++ b/src/x86/ffi.c
@@ -51,6 +51,13 @@
# define __declspec(x) __attribute__((x))
#endif
+#if defined(_MSC_VER) && defined(_M_IX86)
+/* Stack is not 16-byte aligned on Windows. */
+#define STACK_ALIGN(bytes) (bytes)
+#else
+#define STACK_ALIGN(bytes) FFI_ALIGN (bytes, 16)
+#endif
+
/* Perform machine dependent cif processing. */
ffi_status FFI_HIDDEN
ffi_prep_cif_machdep(ffi_cif *cif)
@@ -177,12 +184,7 @@ ffi_prep_cif_machdep(ffi_cif *cif)
bytes = FFI_ALIGN (bytes, t->alignment);
bytes += FFI_ALIGN (t->size, FFI_SIZEOF_ARG);
}
-#if defined(_MSC_VER) && defined(_M_IX86)
- // stack is not 16-bit aligned on Windows
cif->bytes = bytes;
-#else
- cif->bytes = FFI_ALIGN (bytes, 16);
-#endif
return FFI_OK;
}
@@ -290,7 +292,7 @@ ffi_call_int (ffi_cif *cif, void (*fn)(void), void *rvalue,
}
}
- bytes = cif->bytes;
+ bytes = STACK_ALIGN (cif->bytes);
stack = alloca(bytes + sizeof(*frame) + rsize);
argp = (dir < 0 ? stack + bytes : stack);
frame = (struct call_frame *)(stack + bytes);
@@ -434,7 +436,7 @@ ffi_closure_inner (struct closure_frame *frame, char *stack)
rvalue = frame->rettemp;
pabi = &abi_params[cabi];
dir = pabi->dir;
- argp = (dir < 0 ? stack + cif->bytes : stack);
+ argp = (dir < 0 ? stack + STACK_ALIGN (cif->bytes) : stack);
switch (flags)
{
@@ -698,7 +700,7 @@ ffi_raw_call(ffi_cif *cif, void (*fn)(void), void *rvalue, ffi_raw *avalue)
}
}
- bytes = cif->bytes;
+ bytes = STACK_ALIGN (cif->bytes);
argp = stack =
(void *)((uintptr_t)alloca(bytes + sizeof(*frame) + rsize + 15) & ~16);
frame = (struct call_frame *)(stack + bytes);