Commit b066669df22ee8f0b3d51028117c2d10185c4313
2015-10-26T10:38:18
Revert "Remove dynamic indexing of matrices and vectors in HLSL" This reverts commit 3766a40d6fda7e7190514ab7838a3f37169d863f. This CL was causing crashes in UniformHLSL.cpp, where an internal uniform "base" was attempted to be declared in HLSL. Was crashing on an external WebGL 3D canvas page (http://www.taccgl.org/?dbg=t). BUG=546686 Original commit message: Re-landing after fixing D3D9 specific issues. HLSL doesn't support dynamic indexing of matrices and vectors, so replace that with helper functions that unroll dynamic indexing into switch/case and static indexing. Both the indexed vector/matrix expression and the index may have side effects, and these will be evaluated correctly. If necessary, index expressions that have side effects will be written to a temporary variable that will replace the index. Besides dEQP tests, this change is tested by a WebGL 2 conformance test. In the case that a dynamic index is out-of-range, the base ESSL 3.00 spec allows undefined behavior. KHR_robust_buffer_access_behavior adds the requirement that program termination should not occur and that out-of-range reads must return either a value from the active program's memory or zero, and out-of-range writes should only affect the active program's memory or do nothing. This patch clamps out-of-range indices so that either the first or last item of the matrix/vector is accessed. The code is not transformed in case the it fits within the limited subset of ESSL 1.00 given in Appendix A of the spec. If the code isn't within the restricted subset, even ESSL 1.00 shaders may require this workaround. BUG=angleproject:1116 TEST=dEQP-GLES3.functional.shaders.indexing.* (all pass after change) WebGL 2 conformance tests (glsl3/vector-dynamic-indexing.html) Change-Id: I1d4b2e3888e91af7d5eebf743d12778698b6b903 Reviewed-on: https://chromium-review.googlesource.com/308770 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>