[llvm] [NFCI][msan] Refactor into 'horizontalReduce' (PR #152961)
Thurston Dang via llvm-commits
llvm-commits at lists.llvm.org
Mon Aug 11 00:13:21 PDT 2025
https://github.com/thurstond updated https://github.com/llvm/llvm-project/pull/152961
>From f8f42afe366f1b4113e6149b1651d91b535dc3d7 Mon Sep 17 00:00:00 2001
From: Thurston Dang <thurston at google.com>
Date: Mon, 11 Aug 2025 07:01:10 +0000
Subject: [PATCH 1/3] [NFCI][msan] Refactor into 'horizontalReduce'
The functionality is used by two helper functions, and will be used
even more in the future (e.g., https://github.com/llvm/llvm-project/pull/152941).
---
.../Instrumentation/MemorySanitizer.cpp | 91 ++++++++++---------
1 file changed, 48 insertions(+), 43 deletions(-)
diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index 6e8138725375a..5e618fec6dd0c 100644
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -2690,6 +2690,41 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
SC.Done(&I);
}
+ // Perform a bitwise OR on the horizontal pairs (or other specified grouping)
+ // of elements. This is convenient for instrumenting horizontal add/sub.
+ Value *horizontalReduce(IntrinsicInst &I, unsigned ReductionFactor,
+ Value *VectorA, Value* VectorB) {
+ IRBuilder<> IRB(&I);
+ assert(isa<FixedVectorType>(VectorA->getType()));
+ unsigned TotalNumElems = cast<FixedVectorType>(VectorA->getType())->getNumElements();
+
+ if (VectorB) {
+ assert(VectorA->getType() == VectorB->getType());
+ TotalNumElems = TotalNumElems * 2;
+ }
+
+ Value *Or = nullptr;
+
+ for (unsigned i = 0; i < ReductionFactor; i++) {
+ SmallVector<int, 16> Mask;
+ for (unsigned X = 0; X < TotalNumElems; X += ReductionFactor)
+ Mask.push_back(X + i);
+
+ Value *Masked;
+ if (VectorB)
+ Masked = IRB.CreateShuffleVector(VectorA, VectorB, Mask);
+ else
+ Masked = IRB.CreateShuffleVector(VectorA, Mask);
+
+ if (Or)
+ Or = IRB.CreateOr(Or, Masked);
+ else
+ Or = Masked;
+ }
+
+ return Or;
+ }
+
/// Propagate shadow for 1- or 2-vector intrinsics that combine adjacent
/// fields.
///
@@ -2711,31 +2746,16 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
2 * ReturnType->getNumElements());
IRBuilder<> IRB(&I);
- unsigned Width = ParamType->getNumElements() * I.arg_size();
// Horizontal OR of shadow
- SmallVector<int, 8> EvenMask;
- SmallVector<int, 8> OddMask;
- for (unsigned X = 0; X < Width; X += 2) {
- EvenMask.push_back(X);
- OddMask.push_back(X + 1);
- }
-
Value *FirstArgShadow = getShadow(&I, 0);
- Value *EvenShadow;
- Value *OddShadow;
- if (I.arg_size() == 2) {
- Value *SecondArgShadow = getShadow(&I, 1);
- EvenShadow =
- IRB.CreateShuffleVector(FirstArgShadow, SecondArgShadow, EvenMask);
- OddShadow =
- IRB.CreateShuffleVector(FirstArgShadow, SecondArgShadow, OddMask);
- } else {
- EvenShadow = IRB.CreateShuffleVector(FirstArgShadow, EvenMask);
- OddShadow = IRB.CreateShuffleVector(FirstArgShadow, OddMask);
- }
+ Value *SecondArgShadow = nullptr;
+ if (I.arg_size() == 2)
+ SecondArgShadow = getShadow(&I, 1);
+
+ Value *OrShadow = horizontalReduce(I, /*ReductionFactor=*/ 2,
+ FirstArgShadow, SecondArgShadow);
- Value *OrShadow = IRB.CreateOr(EvenShadow, OddShadow);
OrShadow = CreateShadowCast(IRB, OrShadow, getShadowTy(&I));
setShadow(&I, OrShadow);
@@ -2768,23 +2788,14 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
IRBuilder<> IRB(&I);
- unsigned TotalNumElems = ParamType->getNumElements() * I.arg_size();
FixedVectorType *ReinterpretShadowTy = nullptr;
assert(isAligned(Align(ReinterpretElemWidth),
ParamType->getPrimitiveSizeInBits()));
ReinterpretShadowTy = FixedVectorType::get(
IRB.getIntNTy(ReinterpretElemWidth),
ParamType->getPrimitiveSizeInBits() / ReinterpretElemWidth);
- TotalNumElems = ReinterpretShadowTy->getNumElements() * I.arg_size();
// Horizontal OR of shadow
- SmallVector<int, 8> EvenMask;
- SmallVector<int, 8> OddMask;
- for (unsigned X = 0; X < TotalNumElems - 1; X += 2) {
- EvenMask.push_back(X);
- OddMask.push_back(X + 1);
- }
-
Value *FirstArgShadow = getShadow(&I, 0);
FirstArgShadow = IRB.CreateBitCast(FirstArgShadow, ReinterpretShadowTy);
@@ -2796,22 +2807,16 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
Align(2),
cast<FixedVectorType>(FirstArgShadow->getType())->getNumElements()));
- Value *EvenShadow;
- Value *OddShadow;
+ Value *SecondArgShadow = nullptr;
if (I.arg_size() == 2) {
- Value *SecondArgShadow = getShadow(&I, 1);
- SecondArgShadow = IRB.CreateBitCast(SecondArgShadow, ReinterpretShadowTy);
-
- EvenShadow =
- IRB.CreateShuffleVector(FirstArgShadow, SecondArgShadow, EvenMask);
- OddShadow =
- IRB.CreateShuffleVector(FirstArgShadow, SecondArgShadow, OddMask);
- } else {
- EvenShadow = IRB.CreateShuffleVector(FirstArgShadow, EvenMask);
- OddShadow = IRB.CreateShuffleVector(FirstArgShadow, OddMask);
+ SecondArgShadow = getShadow(&I, 1);
+ SecondArgShadow = IRB.CreateBitCast(SecondArgShadow,
+ ReinterpretShadowTy);
}
- Value *OrShadow = IRB.CreateOr(EvenShadow, OddShadow);
+ Value *OrShadow = horizontalReduce(I, /*ReductionFactor=*/ 2,
+ FirstArgShadow, SecondArgShadow);
+
OrShadow = CreateShadowCast(IRB, OrShadow, getShadowTy(&I));
setShadow(&I, OrShadow);
>From e15df775e080fa4ef500a3ac078ba716b2342967 Mon Sep 17 00:00:00 2001
From: Thurston Dang <thurston at google.com>
Date: Mon, 11 Aug 2025 07:11:48 +0000
Subject: [PATCH 2/3] Assert that total number of elements is divisible by
reduction factor
---
llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index 5e618fec6dd0c..94aaddc014ba0 100644
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -2694,7 +2694,6 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
// of elements. This is convenient for instrumenting horizontal add/sub.
Value *horizontalReduce(IntrinsicInst &I, unsigned ReductionFactor,
Value *VectorA, Value* VectorB) {
- IRBuilder<> IRB(&I);
assert(isa<FixedVectorType>(VectorA->getType()));
unsigned TotalNumElems = cast<FixedVectorType>(VectorA->getType())->getNumElements();
@@ -2703,8 +2702,11 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
TotalNumElems = TotalNumElems * 2;
}
+ assert(TotalNumElems % ReductionFactor == 0);
+
Value *Or = nullptr;
+ IRBuilder<> IRB(&I);
for (unsigned i = 0; i < ReductionFactor; i++) {
SmallVector<int, 16> Mask;
for (unsigned X = 0; X < TotalNumElems; X += ReductionFactor)
>From bfca6c329d583bb3cd4d06fbd24f900725f3ba8a Mon Sep 17 00:00:00 2001
From: Thurston Dang <thurston at google.com>
Date: Mon, 11 Aug 2025 07:13:06 +0000
Subject: [PATCH 3/3] Format
---
llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index 94aaddc014ba0..78c428d9a7873 100644
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -2695,7 +2695,8 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
Value *horizontalReduce(IntrinsicInst &I, unsigned ReductionFactor,
Value *VectorA, Value* VectorB) {
assert(isa<FixedVectorType>(VectorA->getType()));
- unsigned TotalNumElems = cast<FixedVectorType>(VectorA->getType())->getNumElements();
+ unsigned TotalNumElems
+ = cast<FixedVectorType>(VectorA->getType())->getNumElements();
if (VectorB) {
assert(VectorA->getType() == VectorB->getType());
More information about the llvm-commits
mailing list