[llvm] [PatternMatch] Add `m_[Shift]OrSelf` matchers. (PR #152924)
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Sun Aug 10 09:04:53 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: Yingwei Zheng (dtcxzyw)
<details>
<summary>Changes</summary>
Address the comment https://github.com/llvm/llvm-project/pull/147414/files#r2228612726.
As they are usually used to match integer packing patterns, it is enough to handle constant shamts.
---
Full diff: https://github.com/llvm/llvm-project/pull/152924.diff
4 Files Affected:
- (modified) llvm/include/llvm/IR/PatternMatch.h (+39)
- (modified) llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp (+13-25)
- (modified) llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (+3-8)
- (modified) llvm/unittests/IR/PatternMatch.cpp (+36)
``````````diff
diff --git a/llvm/include/llvm/IR/PatternMatch.h b/llvm/include/llvm/IR/PatternMatch.h
index 27c5d5ca08cd6..76482ad47c771 100644
--- a/llvm/include/llvm/IR/PatternMatch.h
+++ b/llvm/include/llvm/IR/PatternMatch.h
@@ -1327,6 +1327,45 @@ inline BinaryOp_match<LHS, RHS, Instruction::AShr> m_AShr(const LHS &L,
return BinaryOp_match<LHS, RHS, Instruction::AShr>(L, R);
}
+template <typename LHS_t, unsigned Opcode> struct ShiftLike_match {
+ LHS_t L;
+ uint64_t &R;
+
+ ShiftLike_match(const LHS_t &LHS, uint64_t &RHS) : L(LHS), R(RHS) {}
+
+ template <typename OpTy> bool match(OpTy *V) const {
+ if (auto *Op = dyn_cast<BinaryOperator>(V)) {
+ if (Op->getOpcode() == Opcode)
+ return m_ConstantInt(R).match(Op->getOperand(1)) &&
+ L.match(Op->getOperand(0));
+ }
+ // Interpreted as shiftop V, 0
+ R = 0;
+ return L.match(V);
+ }
+};
+
+/// Matches shl L, ConstShAmt or L itself.
+template <typename LHS>
+inline ShiftLike_match<LHS, Instruction::Shl> m_ShlOrSelf(const LHS &L,
+ uint64_t &R) {
+ return ShiftLike_match<LHS, Instruction::Shl>(L, R);
+}
+
+/// Matches lshr L, ConstShAmt or L itself.
+template <typename LHS>
+inline ShiftLike_match<LHS, Instruction::LShr> m_LShrOrSelf(const LHS &L,
+ uint64_t &R) {
+ return ShiftLike_match<LHS, Instruction::LShr>(L, R);
+}
+
+/// Matches ashr L, ConstShAmt or L itself.
+template <typename LHS>
+inline ShiftLike_match<LHS, Instruction::AShr> m_AShrOrSelf(const LHS &L,
+ uint64_t &R) {
+ return ShiftLike_match<LHS, Instruction::AShr>(L, R);
+}
+
template <typename LHS_t, typename RHS_t, unsigned Opcode,
unsigned WrapFlags = 0, bool Commutable = false>
struct OverflowingBinaryOp_match {
diff --git a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
index 40a7f8043034e..e3c31f96f86d9 100644
--- a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
+++ b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
@@ -617,7 +617,7 @@ struct LoadOps {
LoadInst *RootInsert = nullptr;
bool FoundRoot = false;
uint64_t LoadSize = 0;
- const APInt *Shift = nullptr;
+ uint64_t Shift = 0;
Type *ZextType;
AAMDNodes AATags;
};
@@ -627,17 +627,15 @@ struct LoadOps {
// (ZExt(L1) << shift1) | ZExt(L2) -> ZExt(L3)
static bool foldLoadsRecursive(Value *V, LoadOps &LOps, const DataLayout &DL,
AliasAnalysis &AA) {
- const APInt *ShAmt2 = nullptr;
+ uint64_t ShAmt2;
Value *X;
Instruction *L1, *L2;
// Go to the last node with loads.
- if (match(V, m_OneUse(m_c_Or(
- m_Value(X),
- m_OneUse(m_Shl(m_OneUse(m_ZExt(m_OneUse(m_Instruction(L2)))),
- m_APInt(ShAmt2)))))) ||
- match(V, m_OneUse(m_Or(m_Value(X),
- m_OneUse(m_ZExt(m_OneUse(m_Instruction(L2)))))))) {
+ if (match(V, m_OneUse(m_c_Or(m_Value(X),
+ m_OneUse(m_ShlOrSelf(m_OneUse(m_ZExt(m_OneUse(
+ m_Instruction(L2)))),
+ ShAmt2)))))) {
if (!foldLoadsRecursive(X, LOps, DL, AA) && LOps.FoundRoot)
// Avoid Partial chain merge.
return false;
@@ -646,11 +644,10 @@ static bool foldLoadsRecursive(Value *V, LoadOps &LOps, const DataLayout &DL,
// Check if the pattern has loads
LoadInst *LI1 = LOps.Root;
- const APInt *ShAmt1 = LOps.Shift;
+ uint64_t ShAmt1 = LOps.Shift;
if (LOps.FoundRoot == false &&
- (match(X, m_OneUse(m_ZExt(m_Instruction(L1)))) ||
- match(X, m_OneUse(m_Shl(m_OneUse(m_ZExt(m_OneUse(m_Instruction(L1)))),
- m_APInt(ShAmt1)))))) {
+ match(X, m_OneUse(m_ShlOrSelf(
+ m_OneUse(m_ZExt(m_OneUse(m_Instruction(L1)))), ShAmt1)))) {
LI1 = dyn_cast<LoadInst>(L1);
}
LoadInst *LI2 = dyn_cast<LoadInst>(L2);
@@ -726,13 +723,6 @@ static bool foldLoadsRecursive(Value *V, LoadOps &LOps, const DataLayout &DL,
if (IsBigEndian)
std::swap(ShAmt1, ShAmt2);
- // Find Shifts values.
- uint64_t Shift1 = 0, Shift2 = 0;
- if (ShAmt1)
- Shift1 = ShAmt1->getZExtValue();
- if (ShAmt2)
- Shift2 = ShAmt2->getZExtValue();
-
// First load is always LI1. This is where we put the new load.
// Use the merged load size available from LI1 for forward loads.
if (LOps.FoundRoot) {
@@ -747,7 +737,7 @@ static bool foldLoadsRecursive(Value *V, LoadOps &LOps, const DataLayout &DL,
uint64_t ShiftDiff = IsBigEndian ? LoadSize2 : LoadSize1;
uint64_t PrevSize =
DL.getTypeStoreSize(IntegerType::get(LI1->getContext(), LoadSize1));
- if ((Shift2 - Shift1) != ShiftDiff || (Offset2 - Offset1) != PrevSize)
+ if ((ShAmt2 - ShAmt1) != ShiftDiff || (Offset2 - Offset1) != PrevSize)
return false;
// Update LOps
@@ -824,7 +814,7 @@ static bool foldConsecutiveLoads(Instruction &I, const DataLayout &DL,
// Check if shift needed. We need to shift with the amount of load1
// shift if not zero.
if (LOps.Shift)
- NewOp = Builder.CreateShl(NewOp, ConstantInt::get(I.getContext(), *LOps.Shift));
+ NewOp = Builder.CreateShl(NewOp, LOps.Shift);
I.replaceAllUsesWith(NewOp);
return true;
@@ -860,11 +850,9 @@ static std::optional<PartStore> matchPartStore(Instruction &I,
return std::nullopt;
uint64_t ValWidth = StoredTy->getPrimitiveSizeInBits();
- uint64_t ValOffset = 0;
+ uint64_t ValOffset;
Value *Val;
- if (!match(StoredVal, m_CombineOr(m_Trunc(m_LShr(m_Value(Val),
- m_ConstantInt(ValOffset))),
- m_Trunc(m_Value(Val)))))
+ if (!match(StoredVal, m_Trunc(m_LShrOrSelf(m_Value(Val), ValOffset))))
return std::nullopt;
Value *Ptr = Store->getPointerOperand();
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index d7971e8e3caea..e9cefa6d73de7 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -3605,16 +3605,11 @@ static bool matchSubIntegerPackFromVector(Value *V, Value *&Vec,
int64_t &VecOffset,
SmallBitVector &Mask,
const DataLayout &DL) {
- static const auto m_ConstShlOrSelf = [](const auto &Base, uint64_t &ShlAmt) {
- ShlAmt = 0;
- return m_CombineOr(m_Shl(Base, m_ConstantInt(ShlAmt)), Base);
- };
-
// First try to match extractelement -> zext -> shl
uint64_t VecIdx, ShlAmt;
- if (match(V, m_ConstShlOrSelf(m_ZExtOrSelf(m_ExtractElt(
- m_Value(Vec), m_ConstantInt(VecIdx))),
- ShlAmt))) {
+ if (match(V, m_ShlOrSelf(m_ZExtOrSelf(m_ExtractElt(m_Value(Vec),
+ m_ConstantInt(VecIdx))),
+ ShlAmt))) {
auto *VecTy = dyn_cast<FixedVectorType>(Vec->getType());
if (!VecTy)
return false;
diff --git a/llvm/unittests/IR/PatternMatch.cpp b/llvm/unittests/IR/PatternMatch.cpp
index bb7cc0802b1df..972dac82d3331 100644
--- a/llvm/unittests/IR/PatternMatch.cpp
+++ b/llvm/unittests/IR/PatternMatch.cpp
@@ -2621,4 +2621,40 @@ TEST_F(PatternMatchTest, PtrAdd) {
EXPECT_FALSE(match(OtherGEP, m_PtrAdd(m_Value(A), m_Value(B))));
}
+TEST_F(PatternMatchTest, ShiftOrSelf) {
+ Type *I64Ty = Type::getInt64Ty(Ctx);
+ Constant *LHS = ConstantInt::get(I64Ty, 7);
+ Constant *ShAmt = ConstantInt::get(I64Ty, 16);
+ Value *Shl = IRB.CreateShl(LHS, ShAmt);
+ Value *LShr = IRB.CreateLShr(LHS, ShAmt);
+ Value *AShr = IRB.CreateAShr(LHS, ShAmt);
+ Value *Add = IRB.CreateAdd(LHS, LHS);
+
+ uint64_t ShAmtC;
+ Value *A;
+ EXPECT_TRUE(match(Shl, m_ShlOrSelf(m_Value(A), ShAmtC)));
+ EXPECT_EQ(A, LHS);
+ EXPECT_EQ(ShAmtC, 16U);
+
+ EXPECT_TRUE(match(Add, m_ShlOrSelf(m_Value(A), ShAmtC)));
+ EXPECT_EQ(A, Add);
+ EXPECT_EQ(ShAmtC, 0U);
+
+ EXPECT_TRUE(match(LShr, m_LShrOrSelf(m_Value(A), ShAmtC)));
+ EXPECT_EQ(A, LHS);
+ EXPECT_EQ(ShAmtC, 16U);
+
+ EXPECT_TRUE(match(Add, m_LShrOrSelf(m_Value(A), ShAmtC)));
+ EXPECT_EQ(A, Add);
+ EXPECT_EQ(ShAmtC, 0U);
+
+ EXPECT_TRUE(match(AShr, m_AShrOrSelf(m_Value(A), ShAmtC)));
+ EXPECT_EQ(A, LHS);
+ EXPECT_EQ(ShAmtC, 16U);
+
+ EXPECT_TRUE(match(Add, m_AShrOrSelf(m_Value(A), ShAmtC)));
+ EXPECT_EQ(A, Add);
+ EXPECT_EQ(ShAmtC, 0U);
+}
+
} // anonymous namespace.
``````````
</details>
https://github.com/llvm/llvm-project/pull/152924
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