On Thu, Dec 06, 2012 at 05:08:07PM +0100, Michel Dänzer wrote: > On Mit, 2012-12-05 at 09:32 -0800, Vincent Lejeune wrote: > > Module: Mesa > > Branch: master > > Commit: 0ad1fefd6951aa47ab58a41dc9ee73083cbcf85c > > URL: > > http://cgit.freedesktop.org/mesa/mesa/commit/?id=0ad1fefd6951aa47ab58a41dc9ee73083cbcf85c > > > > Author: Vincent Lejeune <v...@ovi.com> > > Date: Wed Nov 28 00:35:55 2012 +0100 > > > > r600g: Use default mul/mad function for tgsi-to-llvm > > This change breaks the piglit tests glsl-{f,v}s-vec4-indexing-temp-src > on radeonsi. I suspect the same would be true with r600g as well if it > didn't fall back to the non-LLVM backend for this test. > > Comparing the generated code, I've noticed two main differences so far: > > * LLVM now optimizes away some TGSI MUL operations with constant > 1.0, which previously resulted in V_MUL_LEGACY_F32 (non-IEEE > semantics) instructions. > * V_MUL_F32 and V_ADD_F32 (IEEE semantics) are used instead of > V_MAD_LEGACY_F32 (non-IEEE semantics) in some places. >
We really need to fix the SI AsmPrinter and start using the FileCheck tests in LLVM for things like this. > I suspect the problem is a (non-)IEEE semantics mismatch between TGSI > and LLVM introduced by this change. > > What are the semantics of TGSI opcodes? For MUL and MAD, tgsi_exec uses IEEE operations, but it seems like the glsl frontend thinks they are non-IEEE. > BTW, some general issues with this commit: > > The prefix 'r600g:' is misleading, as this change affects radeonsi as > well. I think we've usually used 'radeon/llvm:' for changes > src/gallium/drivers/radeon. > > There is no rationale for this change in the commit log: What is the > intended effect? Why is it a good idea? ... > > I agree with you here. These are things I should have caught during the review. Should we revert this and the associated LLVM changes? -Tom > -- > Earthling Michel Dänzer | http://www.amd.com > Libre software enthusiast | Debian, X and DRI developer > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/mesa-dev _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
