[VectorCombine] Added pattern for recognising the construction of packed integers. #147414
+228
−0
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
@llvm/pr-subscribers-vectorizers @llvm/pr-subscribers-llvm-transforms Author: None (zGoldthorpe) ChangesThis patch extends the vector combiner to simplify the construction of a packed scalar integer from a vector type, such as: define i32 @<!-- -->bitcast.v2i(<4 x i8> %v) {
%v.0 = extractelement <4 x i8> %v, i32 0
%z.0 = zext i8 %v.0 to i32
%v.1 = extractelement <4 x i8> %v, i32 1
%z.1 = zext i8 %v.1 to i32
%s.1 = shl i32 %z.1, 8
%x.1 = or i32 %z.0, %s.1
%v.2 = extractelement <4 x i8> %v, i32 2
%z.2 = zext i8 %v.2 to i32
%s.2 = shl i32 %z.2, 16
%x.2 = or i32 %x.1, %s.2
%v.3 = extractelement <4 x i8> %v, i32 3
%z.3 = zext i8 %v.3 to i32
%s.3 = shl i32 %z.3, 24
%x.3 = or i32 %x.2, %s.3
ret i32 %x.3
}Full diff: https://github.com/llvm/llvm-project/pull/147414.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/Vectorize/VectorCombine.cpp b/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
index fe8d74c43dfdc..ce73a383d2555 100644
--- a/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
+++ b/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
@@ -16,6 +16,7 @@
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/ScopeExit.h"
+#include "llvm/ADT/SmallBitVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
@@ -125,6 +126,7 @@ class VectorCombine {
bool scalarizeLoadExtract(Instruction &I);
bool scalarizeExtExtract(Instruction &I);
bool foldConcatOfBoolMasks(Instruction &I);
+ bool foldIntegerPackFromVector(Instruction &I);
bool foldPermuteOfBinops(Instruction &I);
bool foldShuffleOfBinops(Instruction &I);
bool foldShuffleOfSelects(Instruction &I);
@@ -1957,6 +1959,126 @@ bool VectorCombine::foldConcatOfBoolMasks(Instruction &I) {
return true;
}
+/// Match "shufflevector -> bitcast" or "extractelement -> zext -> shl" patterns
+/// which extract vector elements and pack them in the same relative positions.
+static bool matchSubIntegerPackFromVector(Value *V, Value *&Vec,
+ uint64_t &VecOffset,
+ SmallBitVector &Mask) {
+ 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))) {
+ auto *VecTy = dyn_cast<FixedVectorType>(Vec->getType());
+ if (!VecTy)
+ return false;
+ auto *EltTy = dyn_cast<IntegerType>(VecTy->getElementType());
+ if (!EltTy)
+ return false;
+
+ const unsigned EltBitWidth = EltTy->getBitWidth();
+ const unsigned TargetBitWidth = V->getType()->getIntegerBitWidth();
+ if (TargetBitWidth % EltBitWidth != 0 || ShlAmt % EltBitWidth != 0)
+ return false;
+ const unsigned ShlEltAmt = ShlAmt / EltBitWidth;
+
+ if (ShlEltAmt > VecIdx)
+ return false;
+ VecOffset = VecIdx - ShlEltAmt;
+ Mask.resize(V->getType()->getIntegerBitWidth() / EltBitWidth);
+ Mask.set(ShlEltAmt);
+ return true;
+ }
+
+ // Now try to match shufflevector -> bitcast
+ Value *Lhs, *Rhs;
+ ArrayRef<int> ShuffleMask;
+ if (!match(V, m_BitCast(m_Shuffle(m_Value(Lhs), m_Value(Rhs),
+ m_Mask(ShuffleMask)))))
+ return false;
+ Mask.resize(ShuffleMask.size());
+
+ if (isa<Constant>(Lhs))
+ std::swap(Lhs, Rhs);
+
+ auto *RhsConst = dyn_cast<Constant>(Rhs);
+ if (!RhsConst)
+ return false;
+
+ auto *LhsTy = dyn_cast<FixedVectorType>(Lhs->getType());
+ if (!LhsTy)
+ return false;
+
+ Vec = Lhs;
+ const unsigned NumLhsElts = LhsTy->getNumElements();
+ bool FoundVecOffset = false;
+ for (unsigned Idx = 0; Idx < ShuffleMask.size(); ++Idx) {
+ if (ShuffleMask[Idx] == PoisonMaskElem)
+ return false;
+ const unsigned ShuffleIdx = ShuffleMask[Idx];
+ if (ShuffleIdx >= NumLhsElts) {
+ const unsigned RhsIdx = ShuffleIdx - NumLhsElts;
+ auto *RhsElt =
+ dyn_cast<ConstantInt>(RhsConst->getAggregateElement(RhsIdx));
+ if (!RhsElt || RhsElt->getZExtValue() != 0)
+ return false;
+ continue;
+ }
+
+ if (FoundVecOffset) {
+ if (VecOffset + Idx != ShuffleIdx)
+ return false;
+ } else {
+ if (ShuffleIdx < Idx)
+ return false;
+ VecOffset = ShuffleIdx - Idx;
+ FoundVecOffset = true;
+ }
+ Mask.set(Idx);
+ }
+ return FoundVecOffset;
+}
+/// Try to fold the or of two scalar integers whose contents are packed elements
+/// of the same vector.
+bool VectorCombine::foldIntegerPackFromVector(Instruction &I) {
+ assert(I.getOpcode() == Instruction::Or);
+ Value *LhsVec, *RhsVec;
+ uint64_t LhsVecOffset, RhsVecOffset;
+ SmallBitVector Mask;
+ if (!matchSubIntegerPackFromVector(I.getOperand(0), LhsVec, LhsVecOffset,
+ Mask))
+ return false;
+ if (!matchSubIntegerPackFromVector(I.getOperand(1), RhsVec, RhsVecOffset,
+ Mask))
+ return false;
+ if (LhsVec != RhsVec || LhsVecOffset != RhsVecOffset)
+ return false;
+
+ // Convert into shufflevector -> bitcast
+ SmallVector<int> ShuffleMask;
+ ShuffleMask.reserve(Mask.size());
+ const unsigned ZeroVecIdx =
+ cast<FixedVectorType>(LhsVec->getType())->getNumElements();
+ for (unsigned Idx = 0; Idx < Mask.size(); ++Idx) {
+ if (Mask.test(Idx))
+ ShuffleMask.push_back(LhsVecOffset + Idx);
+ else
+ ShuffleMask.push_back(ZeroVecIdx);
+ }
+
+ Value *MaskedVec = Builder.CreateShuffleVector(
+ LhsVec, Constant::getNullValue(LhsVec->getType()), ShuffleMask,
+ LhsVec->getName() + ".extract");
+ Value *CastedVec = Builder.CreateBitCast(MaskedVec, I.getType(), I.getName());
+ replaceValue(I, *CastedVec);
+ return true;
+}
+
/// Try to convert "shuffle (binop (shuffle, shuffle)), undef"
/// --> "binop (shuffle), (shuffle)".
bool VectorCombine::foldPermuteOfBinops(Instruction &I) {
@@ -3742,6 +3864,9 @@ bool VectorCombine::run() {
if (Opcode == Instruction::Store)
MadeChange |= foldSingleElementStore(I);
+ if (isa<IntegerType>(I.getType()) && Opcode == Instruction::Or)
+ MadeChange |= foldIntegerPackFromVector(I);
+
// If this is an early pipeline invocation of this pass, we are done.
if (TryEarlyFoldsOnly)
return;
diff --git a/llvm/test/Transforms/VectorCombine/packed-integers.ll b/llvm/test/Transforms/VectorCombine/packed-integers.ll
new file mode 100644
index 0000000000000..f01179bbde13c
--- /dev/null
+++ b/llvm/test/Transforms/VectorCombine/packed-integers.ll
@@ -0,0 +1,108 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S -passes=vector-combine %s | FileCheck %s
+
+define i32 @bitcast.v2i(<4 x i8> %v) {
+; CHECK-LABEL: define i32 @bitcast.v2i(
+; CHECK-SAME: <4 x i8> [[V:%.*]]) {
+; CHECK-NEXT: [[X_3:%.*]] = bitcast <4 x i8> [[V]] to i32
+; CHECK-NEXT: ret i32 [[X_3]]
+;
+ %v.0 = extractelement <4 x i8> %v, i32 0
+ %z.0 = zext i8 %v.0 to i32
+
+ %v.1 = extractelement <4 x i8> %v, i32 1
+ %z.1 = zext i8 %v.1 to i32
+ %s.1 = shl i32 %z.1, 8
+ %x.1 = or i32 %z.0, %s.1
+
+ %v.2 = extractelement <4 x i8> %v, i32 2
+ %z.2 = zext i8 %v.2 to i32
+ %s.2 = shl i32 %z.2, 16
+ %x.2 = or i32 %x.1, %s.2
+
+ %v.3 = extractelement <4 x i8> %v, i32 3
+ %z.3 = zext i8 %v.3 to i32
+ %s.3 = shl i32 %z.3, 24
+ %x.3 = or i32 %x.2, %s.3
+
+ ret i32 %x.3
+}
+
+define i32 @bitcast.v2i.tree(<4 x i8> %v) {
+; CHECK-LABEL: define i32 @bitcast.v2i.tree(
+; CHECK-SAME: <4 x i8> [[V:%.*]]) {
+; CHECK-NEXT: [[X:%.*]] = bitcast <4 x i8> [[V]] to i32
+; CHECK-NEXT: ret i32 [[X]]
+;
+ %v.0 = extractelement <4 x i8> %v, i32 0
+ %z.0 = zext i8 %v.0 to i32
+
+ %v.1 = extractelement <4 x i8> %v, i32 1
+ %z.1 = zext i8 %v.1 to i32
+ %s.1 = shl i32 %z.1, 8
+ %x.1 = or i32 %z.0, %s.1
+
+ %v.2 = extractelement <4 x i8> %v, i32 2
+ %z.2 = zext i8 %v.2 to i32
+ %s.2 = shl i32 %z.2, 16
+
+ %v.3 = extractelement <4 x i8> %v, i32 3
+ %z.3 = zext i8 %v.3 to i32
+ %s.3 = shl i32 %z.3, 24
+ %x.3 = or i32 %s.2, %s.3
+
+ %x = or i32 %x.1, %x.3
+
+ ret i32 %x
+}
+
+define i32 @extract.i32(<8 x i8> %v) {
+; CHECK-LABEL: define i32 @extract.i32(
+; CHECK-SAME: <8 x i8> [[V:%.*]]) {
+; CHECK-NEXT: [[V_EXTRACT4:%.*]] = shufflevector <8 x i8> [[V]], <8 x i8> zeroinitializer, <4 x i32> <i32 3, i32 4, i32 5, i32 6>
+; CHECK-NEXT: [[X_3:%.*]] = bitcast <4 x i8> [[V_EXTRACT4]] to i32
+; CHECK-NEXT: ret i32 [[X_3]]
+;
+ %v.0 = extractelement <8 x i8> %v, i32 3
+ %z.0 = zext i8 %v.0 to i32
+
+ %v.1 = extractelement <8 x i8> %v, i32 4
+ %z.1 = zext i8 %v.1 to i32
+ %s.1 = shl i32 %z.1, 8
+ %x.1 = or i32 %z.0, %s.1
+
+ %v.2 = extractelement <8 x i8> %v, i32 5
+ %z.2 = zext i8 %v.2 to i32
+ %s.2 = shl i32 %z.2, 16
+ %x.2 = or i32 %x.1, %s.2
+
+ %v.3 = extractelement <8 x i8> %v, i32 6
+ %z.3 = zext i8 %v.3 to i32
+ %s.3 = shl i32 %z.3, 24
+ %x.3 = or i32 %x.2, %s.3
+
+ ret i32 %x.3
+}
+
+define i32 @partial(<4 x i8> %v) {
+; CHECK-LABEL: define i32 @partial(
+; CHECK-SAME: <4 x i8> [[V:%.*]]) {
+; CHECK-NEXT: [[V_EXTRACT2:%.*]] = shufflevector <4 x i8> [[V]], <4 x i8> zeroinitializer, <4 x i32> <i32 0, i32 1, i32 4, i32 3>
+; CHECK-NEXT: [[X_3:%.*]] = bitcast <4 x i8> [[V_EXTRACT2]] to i32
+; CHECK-NEXT: ret i32 [[X_3]]
+;
+ %v.0 = extractelement <4 x i8> %v, i32 0
+ %z.0 = zext i8 %v.0 to i32
+
+ %v.1 = extractelement <4 x i8> %v, i32 1
+ %z.1 = zext i8 %v.1 to i32
+ %s.1 = shl i32 %z.1, 8
+ %x.1 = or i32 %z.0, %s.1
+
+ %v.3 = extractelement <4 x i8> %v, i32 3
+ %z.3 = zext i8 %v.3 to i32
+ %s.3 = shl i32 %z.3, 24
+ %x.3 = or i32 %x.1, %s.3
+
+ ret i32 %x.3
+}
|
|
@arsenm @macurtis-amd pinging to request review |
macurtis-amd
approved these changes
Jul 10, 2025
topperc
reviewed
Jul 10, 2025
arsenm
reviewed
Jul 11, 2025
arsenm
reviewed
Jul 11, 2025
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This patch extends the vector combiner to simplify the construction of a packed scalar integer from a vector type, such as: