[llvm] 7660981 - [LSR] Use computeConstantDifference()

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2024-08-28T12:20:59+02:00
New Revision: 7660981402bccaad0e351a65913ebd37436e4816

URL: https://github.com/llvm/llvm-project/commit/7660981402bccaad0e351a65913ebd37436e4816
DIFF: https://github.com/llvm/llvm-project/commit/7660981402bccaad0e351a65913ebd37436e4816.diff

LOG: [LSR] Use computeConstantDifference()

This API is faster than getMinusSCEV() and a SCEVConstant cast.

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index a62b87fe2a53d4..3ca3818938fd26 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -5304,17 +5304,17 @@ static bool IsSimplerBaseSCEVForTarget(const TargetTransformInfo &TTI,
        cast<SCEVAddRecExpr>(Best)->getLoop() !=
            cast<SCEVAddRecExpr>(Reg)->getLoop()))
     return false;
-  const auto *Diff = dyn_cast<SCEVConstant>(SE.getMinusSCEV(Best, Reg));
+  std::optional<APInt> Diff = SE.computeConstantDifference(Best, Reg);
   if (!Diff)
     return false;
 
   return TTI.isLegalAddressingMode(
              AccessType.MemTy, /*BaseGV=*/nullptr,
-             /*BaseOffset=*/Diff->getAPInt().getSExtValue(),
+             /*BaseOffset=*/Diff->getSExtValue(),
              /*HasBaseReg=*/true, /*Scale=*/0, AccessType.AddrSpace) &&
          !TTI.isLegalAddressingMode(
              AccessType.MemTy, /*BaseGV=*/nullptr,
-             /*BaseOffset=*/-Diff->getAPInt().getSExtValue(),
+             /*BaseOffset=*/-Diff->getSExtValue(),
              /*HasBaseReg=*/true, /*Scale=*/0, AccessType.AddrSpace);
 }