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[InstCombine] visitCallInst - pull out repeated bswap scalar type bitwidth. NFC.

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This commit is contained in:
Simon Pilgrim 2022-02-18 17:33:11 +00:00
parent 9415fbbbcf
commit be1ffda0a5
1 changed files with 3 additions and 3 deletions
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6
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
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@ -1295,9 +1295,10 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
KnownBits Known = computeKnownBits(IIOperand, 0, II);
uint64_t LZ = alignDown(Known.countMinLeadingZeros(), 8);
uint64_t TZ = alignDown(Known.countMinTrailingZeros(), 8);
unsigned BW = Known.getBitWidth();
// bswap(x) -> shift(x) if x has exactly one "active byte"
if (Known.getBitWidth() - LZ - TZ == 8) {
if (BW - LZ - TZ == 8) {
assert(LZ != TZ && "active byte cannot be in the middle");
if (LZ > TZ) // -> shl(x) if the "active byte" is in the low part of x
return BinaryOperator::CreateNUWShl(
@ -1309,8 +1310,7 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
// bswap(trunc(bswap(x))) -> trunc(lshr(x, c))
if (match(IIOperand, m_Trunc(m_BSwap(m_Value(X))))) {
unsigned C = X->getType()->getScalarSizeInBits() -
IIOperand->getType()->getScalarSizeInBits();
unsigned C = X->getType()->getScalarSizeInBits() - BW;
Value *CV = ConstantInt::get(X->getType(), C);
Value *V = Builder.CreateLShr(X, CV);
return new TruncInst(V, IIOperand->getType());