Stanislav Mekhanoshin 4e48d88543 [SLP] Control maximum vectorization factor from TTI ... D82227 has added a proper check to limit PHI vectorization to the maximum vector register size. That unfortunately resulted in at least a couple of regressions on SystemZ and x86. This change reverts PHI handling from D82227 and replaces it with a more general check in SLPVectorizerPass::tryToVectorizeList(). Moved to tryToVectorizeList() it allows to restart vectorization if initial chunk fails. However, this function is more general and handles not only PHI but everything which SLP handles. If vectorization factor would be limited to maximum vector register size it would limit much more vectorization than before leading to further regressions. Therefore a new TTI callback getMaximumVF() is added with the default 0 to preserve current behavior and limit nothing. Then targets can decide what is better for them. The callback gets ElementSize just like a similar getMinimumVF() function and the main opcode of the chain. The latter is to avoid regressions at least on the AMDGPU. We can have loads and stores up to 128 bit wide, and <2 x 16> bit vector math on some subtargets, where the rest shall not be vectorized. I.e. we need to differentiate based on the element size and operation itself. Differential Revision: https://reviews.llvm.org/D92059		2020-12-14 08:49:40 -08:00
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llvm	[SLP] Control maximum vectorization factor from TTI	2020-12-14 08:49:40 -08:00
llvm-c	[llvm-c] Delete unimplemented llvm-c/LinkTimeOptimizer.h	2020-12-06 15:18:25 -08:00