diff options
Diffstat (limited to 'llvm/lib/Transforms')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp | 18 |
1 files changed, 5 insertions, 13 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp index bdd9a43be27..c1872a1c9ce 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -3479,22 +3479,14 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) { bool Signed = II->getIntrinsicID() == Intrinsic::amdgcn_sbfe; - // TODO: Also emit sub if only width is constant. - if (!CWidth && COffset && Offset == 0) { - Constant *KSize = ConstantInt::get(COffset->getType(), IntSize); - Value *ShiftVal = Builder.CreateSub(KSize, II->getArgOperand(2)); - ShiftVal = Builder.CreateZExt(ShiftVal, II->getType()); - - Value *Shl = Builder.CreateShl(Src, ShiftVal); - Value *RightShift = Signed ? Builder.CreateAShr(Shl, ShiftVal) - : Builder.CreateLShr(Shl, ShiftVal); - RightShift->takeName(II); - return replaceInstUsesWith(*II, RightShift); - } - if (!CWidth || !COffset) break; + // The case of Width == 0 is handled above, which makes this tranformation + // safe. If Width == 0, then the ashr and lshr instructions become poison + // value since the shift amount would be equal to the bit size. + assert(Width != 0); + // TODO: This allows folding to undef when the hardware has specific // behavior? if (Offset + Width < IntSize) { |
