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* Revert "[AMDGPU] Invert the handling of skip insertion."Nicolai Hähnle2020-02-031-1/+1
| | | | | | | | | This reverts commit 0dc6c249bffac9f23a605ce4e42a84341da3ddbd. The commit is reported to cause a regression in piglit/bin/glsl-vs-loop for Mesa. (cherry picked from commit a80291ce10ba9667352adcc895f9668144f5f616)
* [AMDGPU] Invert the handling of skip insertion.cdevadas2020-01-151-1/+1
| | | | | | | | | | | | | | | The current implementation of skip insertion (SIInsertSkip) makes it a mandatory pass required for correctness. Initially, the idea was to have an optional pass. This patch inserts the s_cbranch_execz upfront during SILowerControlFlow to skip over the sections of code when no lanes are active. Later, SIRemoveShortExecBranches removes the skips for short branches, unless there is a sideeffect and the skip branch is really necessary. This new pass will replace the handling of skip insertion in the existing SIInsertSkip Pass. Differential revision: https://reviews.llvm.org/D68092
* [MBP] Move a latch block with conditional exit and multi predecessors to top ↵Guozhi Wei2019-06-141-1/+1
| | | | | | | | | | | | | | | | of loop Current findBestLoopTop can find and move one kind of block to top, a latch block has one successor. Another common case is: * a latch block * it has two successors, one is loop header, another is exit * it has more than one predecessors If it is below one of its predecessors P, only P can fall through to it, all other predecessors need a jump to it, and another conditional jump to loop header. If it is moved before loop header, all its predecessors jump to it, then fall through to loop header. So all its predecessors except P can reduce one taken branch. Differential Revision: https://reviews.llvm.org/D43256 llvm-svn: 363471
* AMDGPU/SI: Avoid moving PHIs to VALU when phi values are defined in scalar ↵Tom Stellard2016-11-291-1/+1
| | | | | | | | | | | | branches Reviewers: arsenm Subscribers: arsenm, llvm-commits, kzhuravl Differential Revision: https://reviews.llvm.org/D23417 llvm-svn: 288095
* [AMDGPU] Allow hoisting of comparisons out of a loop and eliminate condition ↵Stanislav Mekhanoshin2016-11-281-0/+46
copies Codegen prepare sinks comparisons close to a user is we have only one register for conditions. For AMDGPU we have many SGPRs capable to hold vector conditions. Changed BE to report we have many condition registers. That way IR LICM pass would hoist an invariant comparison out of a loop and codegen prepare will not sink it. With that done a condition is calculated in one block and used in another. Current behavior is to store workitem's condition in a VGPR using v_cndmask_b32 and then restore it with yet another v_cmp instruction from that v_cndmask's result. To mitigate the issue a propagation of source SGPR pair in place of v_cmp is implemented. Additional side effect of this is that we may consume less VGPRs at a cost of more SGPRs in case if holding of multiple conditions is needed, and that is a clear win in most cases. Differential Revision: https://reviews.llvm.org/D26114 llvm-svn: 288053
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