diff options
Diffstat (limited to 'lib/Transforms/Scalar/CodeGenPrepare.cpp')
-rw-r--r-- | lib/Transforms/Scalar/CodeGenPrepare.cpp | 29 |
1 files changed, 22 insertions, 7 deletions
diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp index cfca726f26..57a648f7b9 100644 --- a/lib/Transforms/Scalar/CodeGenPrepare.cpp +++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp @@ -1174,17 +1174,32 @@ static bool isFormingBranchFromSelectProfitable(SelectInst *SI) { } +/// If we have a SelectInst that will likely profit from branch prediction, +/// turn it into a branch. bool CodeGenPrepare::OptimizeSelectInst(SelectInst *SI) { - // If we have a SelectInst that will likely profit from branch prediction, - // turn it into a branch. - if (DisableSelectToBranch || OptSize || !TLI || - !TLI->isPredictableSelectExpensive()) - return false; + bool VectorCond = !SI->getCondition()->getType()->isIntegerTy(1); - if (!SI->getCondition()->getType()->isIntegerTy(1) || - !isFormingBranchFromSelectProfitable(SI)) + // Can we convert the 'select' to CF ? + if (DisableSelectToBranch || OptSize || !TLI || VectorCond) return false; + TargetLowering::SelectSupportKind SelectKind; + if (VectorCond) + SelectKind = TargetLowering::VectorMaskSelect; + else if (SI->getType()->isVectorTy()) + SelectKind = TargetLowering::ScalarCondVectorVal; + else + SelectKind = TargetLowering::ScalarValSelect; + + // Do we have efficient codegen support for this kind of 'selects' ? + if (TLI->isSelectSupported(SelectKind)) { + // We have efficient codegen support for the select instruction. + // Check if it is profitable to keep this 'select'. + if (!TLI->isPredictableSelectExpensive() || + !isFormingBranchFromSelectProfitable(SI)) + return false; + } + ModifiedDT = true; // First, we split the block containing the select into 2 blocks. |