Zap sitofp/fptoui pairs. In all cases when the sign difference
matters, the result is undefined anyway.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54396 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index fbd0d20..44083bc 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -7750,27 +7750,41 @@
}
Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) {
- // fptoui(uitofp(X)) --> X if the intermediate type has enough bits in its
- // mantissa to accurately represent all values of X. For example, do not
- // do this with i64->float->i64.
- if (UIToFPInst *SrcI = dyn_cast<UIToFPInst>(FI.getOperand(0)))
- if (SrcI->getOperand(0)->getType() == FI.getType() &&
- (int)FI.getType()->getPrimitiveSizeInBits() < /*extra bit for sign */
- SrcI->getType()->getFPMantissaWidth())
- return ReplaceInstUsesWith(FI, SrcI->getOperand(0));
+ Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
+ if (OpI == 0)
+ return commonCastTransforms(FI);
+
+ // fptoui(uitofp(X)) --> X
+ // fptoui(sitofp(X)) --> X
+ // This is safe if the intermediate type has enough bits in its mantissa to
+ // accurately represent all values of X. For example, do not do this with
+ // i64->float->i64. This is also safe for sitofp case, because any negative
+ // 'X' value would cause an undefined result for the fptoui.
+ if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
+ OpI->getOperand(0)->getType() == FI.getType() &&
+ (int)FI.getType()->getPrimitiveSizeInBits() < /*extra bit for sign */
+ OpI->getType()->getFPMantissaWidth())
+ return ReplaceInstUsesWith(FI, OpI->getOperand(0));
return commonCastTransforms(FI);
}
Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) {
- // fptosi(sitofp(X)) --> X if the intermediate type has enough bits in its
- // mantissa to accurately represent all values of X. For example, do not
- // do this with i64->float->i64.
- if (SIToFPInst *SrcI = dyn_cast<SIToFPInst>(FI.getOperand(0)))
- if (SrcI->getOperand(0)->getType() == FI.getType() &&
- (int)FI.getType()->getPrimitiveSizeInBits() <=
- SrcI->getType()->getFPMantissaWidth())
- return ReplaceInstUsesWith(FI, SrcI->getOperand(0));
+ Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
+ if (OpI == 0)
+ return commonCastTransforms(FI);
+
+ // fptosi(sitofp(X)) --> X
+ // fptosi(uitofp(X)) --> X
+ // This is safe if the intermediate type has enough bits in its mantissa to
+ // accurately represent all values of X. For example, do not do this with
+ // i64->float->i64. This is also safe for sitofp case, because any negative
+ // 'X' value would cause an undefined result for the fptoui.
+ if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
+ OpI->getOperand(0)->getType() == FI.getType() &&
+ (int)FI.getType()->getPrimitiveSizeInBits() <=
+ OpI->getType()->getFPMantissaWidth())
+ return ReplaceInstUsesWith(FI, OpI->getOperand(0));
return commonCastTransforms(FI);
}