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[ExpandMemCmp] Use m_SpecificInt to simplify code. NFC #121532

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Merged
merged 1 commit into from
Jan 3, 2025
Merged

[ExpandMemCmp] Use m_SpecificInt to simplify code. NFC #121532

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6 changes: 3 additions & 3 deletions llvm/lib/CodeGen/ExpandMemCmp.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -669,15 +669,15 @@ Value *MemCmpExpansion::getMemCmpOneBlock() {
if (CI->hasOneUser()) {
auto *UI = cast<Instruction>(*CI->user_begin());
CmpPredicate Pred = ICmpInst::Predicate::BAD_ICMP_PREDICATE;
uint64_t Shift;
bool NeedsZExt = false;
// This is a special case because instead of checking if the result is less
// than zero:
// bool result = memcmp(a, b, NBYTES) < 0;
// Compiler is clever enough to generate the following code:
// bool result = memcmp(a, b, NBYTES) >> 31;
if (match(UI, m_LShr(m_Value(), m_ConstantInt(Shift))) &&
Shift == (CI->getType()->getIntegerBitWidth() - 1)) {
if (match(UI,
m_LShr(m_Value(),
m_SpecificInt(CI->getType()->getIntegerBitWidth() - 1)))) {
Pred = ICmpInst::ICMP_SLT;
NeedsZExt = true;
} else {
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