[llvm] 00f0381 - [InstCombine] Refactor foldSelectICmpAndOr to use `decomposeBitTestICmp` instead of bespoke logic
Noah Goldstein via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 16 20:41:53 PDT 2023
Author: Noah Goldstein
Date: 2023-08-16T22:43:05-05:00
New Revision: 00f03814611e47e1a459b4d287b0e847a34ab9d4
URL: https://github.com/llvm/llvm-project/commit/00f03814611e47e1a459b4d287b0e847a34ab9d4
DIFF: https://github.com/llvm/llvm-project/commit/00f03814611e47e1a459b4d287b0e847a34ab9d4.diff
LOG: [InstCombine] Refactor foldSelectICmpAndOr to use `decomposeBitTestICmp` instead of bespoke logic
This is essentially NFC as the cases `decomposeBitTestICmp` covers
that weren't already covered explicitly, will be canonicalized into
the cases explicitly covered. As well the unsigned cases don't apply
as the `Mask` is not a power of 2.
That being said, using a well established helper is less bug prone and
if some canonicalization changes, will prevent regressions here.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D148744
Added:
Modified:
llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index d32435895576d5..d5be03dd425773 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -714,8 +714,8 @@ static Value *foldSelectICmpAndOr(const ICmpInst *IC, Value *TrueVal,
Value *CmpRHS = IC->getOperand(1);
unsigned C1Log;
- bool IsEqualZero;
bool NeedAnd = false;
+ CmpInst::Predicate Pred = IC->getPredicate();
if (IC->isEquality()) {
if (!match(CmpRHS, m_Zero()))
return nullptr;
@@ -725,17 +725,13 @@ static Value *foldSelectICmpAndOr(const ICmpInst *IC, Value *TrueVal,
return nullptr;
C1Log = C1->logBase2();
- IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_EQ;
} else {
- // We also need to recognize (icmp slt X, 0) and (icmp sgt X, -1).
- if (IC->getPredicate() == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes()))
- IsEqualZero = true;
- if (IC->getPredicate() == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero()))
- IsEqualZero = false;
- else
+ APInt C1;
+ if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, CmpLHS, C1) ||
+ !C1.isPowerOf2())
return nullptr;
- C1Log = CmpLHS->getType()->getScalarSizeInBits() - 1;
+ C1Log = C1.logBase2();
NeedAnd = true;
}
@@ -745,11 +741,11 @@ static Value *foldSelectICmpAndOr(const ICmpInst *IC, Value *TrueVal,
if (match(FalseVal, m_Or(m_Specific(TrueVal), m_Power2(C2)))) {
Y = TrueVal;
Or = FalseVal;
- NeedXor = !IsEqualZero;
+ NeedXor = Pred == ICmpInst::ICMP_NE;
} else if (match(TrueVal, m_Or(m_Specific(FalseVal), m_Power2(C2)))) {
Y = FalseVal;
Or = TrueVal;
- NeedXor = IsEqualZero;
+ NeedXor = Pred == ICmpInst::ICMP_EQ;
} else {
return nullptr;
}
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