[llvm] [PreISelIntrinsicLowering] Reuse previously generated GlobalVariable for memset_pattern16 when possible (PR #144677)
Alex Bradbury via llvm-commits
llvm-commits at lists.llvm.org
Wed Jun 18 04:55:22 PDT 2025
https://github.com/asb created https://github.com/llvm/llvm-project/pull/144677
As Constants are already uniquified, we can use a map to keep track of whether a GlobalVariable was produced for a given Constant or not. Repeated globals with the same value was one of the codegen differences noted in #126736. This patch removes that diff, producing cleaner output.
>From 20ac459035337996d1d51c160d7fa0f4032fa79b Mon Sep 17 00:00:00 2001
From: Alex Bradbury <asb at igalia.com>
Date: Wed, 18 Jun 2025 12:51:40 +0100
Subject: [PATCH] [PreISelIntrinsicLowering] Reuse previously generated
GlobalVariable for memset_pattern16 when possible
As Constants are already uniquified, we can use a map to keep track of
whether a GlobalVariable was produced for a given Constant or not.
Repeated globals with the same value was one of the codegen differences
noted in #126736. This patch removes that diff, producing cleaner
output.
---
llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp | 32 +++++++++++------
.../X86/memset-pattern.ll | 34 ++++++++-----------
2 files changed, 36 insertions(+), 30 deletions(-)
diff --git a/llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp b/llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp
index 6f52b7cac1d46..1b05dd46252fb 100644
--- a/llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp
+++ b/llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp
@@ -68,7 +68,9 @@ struct PreISelIntrinsicLowering {
static bool shouldExpandMemIntrinsicWithSize(Value *Size,
const TargetTransformInfo &TTI);
- bool expandMemIntrinsicUses(Function &F) const;
+ bool
+ expandMemIntrinsicUses(Function &F,
+ DenseMap<Constant *, GlobalVariable *> &CMap) const;
bool lowerIntrinsics(Module &M) const;
};
@@ -287,7 +289,8 @@ static Constant *getMemSetPattern16Value(MemSetPatternInst *Inst,
// TODO: Handle atomic memcpy and memcpy.inline
// TODO: Pass ScalarEvolution
-bool PreISelIntrinsicLowering::expandMemIntrinsicUses(Function &F) const {
+bool PreISelIntrinsicLowering::expandMemIntrinsicUses(
+ Function &F, DenseMap<Constant *, GlobalVariable *> &CMap) const {
Intrinsic::ID ID = F.getIntrinsicID();
bool Changed = false;
@@ -404,13 +407,20 @@ bool PreISelIntrinsicLowering::expandMemIntrinsicUses(Function &F) const {
// global.
assert(Memset->getRawDest()->getType()->getPointerAddressSpace() == 0 &&
"Should have skipped if non-zero AS");
- GlobalVariable *GV = new GlobalVariable(
- *M, PatternValue->getType(), /*isConstant=*/true,
- GlobalValue::PrivateLinkage, PatternValue, ".memset_pattern");
- GV->setUnnamedAddr(
- GlobalValue::UnnamedAddr::Global); // Ok to merge these.
- // TODO: Consider relaxing alignment requirement.
- GV->setAlignment(Align(16));
+ GlobalVariable *GV;
+ auto It = CMap.find(PatternValue);
+ if (It != CMap.end()) {
+ GV = It->second;
+ } else {
+ GV = new GlobalVariable(
+ *M, PatternValue->getType(), /*isConstant=*/true,
+ GlobalValue::PrivateLinkage, PatternValue, ".memset_pattern");
+ GV->setUnnamedAddr(
+ GlobalValue::UnnamedAddr::Global); // Ok to merge these.
+ // TODO: Consider relaxing alignment requirement.
+ GV->setAlignment(Align(16));
+ CMap[PatternValue] = GV;
+ }
Value *PatternPtr = GV;
Value *NumBytes = Builder.CreateMul(
TLI.getAsSizeT(DL.getTypeAllocSize(Memset->getValue()->getType()),
@@ -439,6 +449,8 @@ bool PreISelIntrinsicLowering::expandMemIntrinsicUses(Function &F) const {
}
bool PreISelIntrinsicLowering::lowerIntrinsics(Module &M) const {
+ // Map unique constants to globals.
+ DenseMap<Constant *, GlobalVariable *> CMap;
bool Changed = false;
for (Function &F : M) {
switch (F.getIntrinsicID()) {
@@ -450,7 +462,7 @@ bool PreISelIntrinsicLowering::lowerIntrinsics(Module &M) const {
case Intrinsic::memset:
case Intrinsic::memset_inline:
case Intrinsic::experimental_memset_pattern:
- Changed |= expandMemIntrinsicUses(F);
+ Changed |= expandMemIntrinsicUses(F, CMap);
break;
case Intrinsic::load_relative:
Changed |= lowerLoadRelative(F);
diff --git a/llvm/test/Transforms/PreISelIntrinsicLowering/X86/memset-pattern.ll b/llvm/test/Transforms/PreISelIntrinsicLowering/X86/memset-pattern.ll
index 64cc4ba281635..aaca5a6c87b4f 100644
--- a/llvm/test/Transforms/PreISelIntrinsicLowering/X86/memset-pattern.ll
+++ b/llvm/test/Transforms/PreISelIntrinsicLowering/X86/memset-pattern.ll
@@ -4,16 +4,10 @@
;.
; CHECK: @G = global i32 5
; CHECK: @.memset_pattern = private unnamed_addr constant [2 x ptr] [ptr @G, ptr @G], align 16
-; CHECK: @.memset_pattern.1 = private unnamed_addr constant [2 x ptr] [ptr @G, ptr @G], align 16
-; CHECK: @.memset_pattern.2 = private unnamed_addr constant [2 x i64] [i64 -6148895925951734307, i64 -6148895925951734307], align 16
-; CHECK: @.memset_pattern.3 = private unnamed_addr constant [2 x i64] [i64 -6148895925951734307, i64 -6148895925951734307], align 16
-; CHECK: @.memset_pattern.4 = private unnamed_addr constant [2 x i64] [i64 -6148895925951734307, i64 -6148895925951734307], align 16
-; CHECK: @.memset_pattern.5 = private unnamed_addr constant [2 x i64] [i64 4614256656552045848, i64 4614256656552045848], align 16
-; CHECK: @.memset_pattern.6 = private unnamed_addr constant [8 x i16] [i16 -21555, i16 -21555, i16 -21555, i16 -21555, i16 -21555, i16 -21555, i16 -21555, i16 -21555], align 16
-; CHECK: @.memset_pattern.7 = private unnamed_addr constant i128 -113427455635030943652277463699152839203, align 16
-; CHECK: @.memset_pattern.8 = private unnamed_addr constant i128 -113427455635030943652277463699152839203, align 16
-; CHECK: @.memset_pattern.9 = private unnamed_addr constant i128 -113427455635030943652277463699152839203, align 16
-; CHECK: @.memset_pattern.10 = private unnamed_addr constant i128 -113427455635030943652277463699152839203, align 16
+; CHECK: @.memset_pattern.1 = private unnamed_addr constant [2 x i64] [i64 -6148895925951734307, i64 -6148895925951734307], align 16
+; CHECK: @.memset_pattern.2 = private unnamed_addr constant [2 x i64] [i64 4614256656552045848, i64 4614256656552045848], align 16
+; CHECK: @.memset_pattern.3 = private unnamed_addr constant [8 x i16] [i16 -21555, i16 -21555, i16 -21555, i16 -21555, i16 -21555, i16 -21555, i16 -21555, i16 -21555], align 16
+; CHECK: @.memset_pattern.4 = private unnamed_addr constant i128 -113427455635030943652277463699152839203, align 16
;.
define void @memset_pattern_i128_1_dynvalue(ptr %a, i128 %value) nounwind {
; CHECK-LABEL: define void @memset_pattern_i128_1_dynvalue(
@@ -36,7 +30,7 @@ define void @memset_pattern_i128_1_dynvalue(ptr %a, i128 %value) nounwind {
define void @memset_pattern_i128_1(ptr %a, i128 %value) nounwind {
; CHECK-LABEL: define void @memset_pattern_i128_1(
; CHECK-SAME: ptr [[A:%.*]], i128 [[VALUE:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.7, i64 16)
+; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.4, i64 16)
; CHECK-NEXT: ret void
;
tail call void @llvm.experimental.memset.pattern(ptr %a, i128 u0xaaaaaaaabbbbbbbbccccccccdddddddd, i64 1, i1 false)
@@ -64,7 +58,7 @@ define void @memset_pattern_i128_1_nz_as(ptr addrspace(1) %a, i128 %value) nounw
define void @memset_pattern_i128_1_align_attr(ptr align(16) %a, i128 %value) nounwind {
; CHECK-LABEL: define void @memset_pattern_i128_1_align_attr(
; CHECK-SAME: ptr align 16 [[A:%.*]], i128 [[VALUE:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: call void @memset_pattern16(ptr align 16 [[A]], ptr @.memset_pattern.8, i64 16)
+; CHECK-NEXT: call void @memset_pattern16(ptr align 16 [[A]], ptr @.memset_pattern.4, i64 16)
; CHECK-NEXT: ret void
;
tail call void @llvm.experimental.memset.pattern(ptr align(16) %a, i128 u0xaaaaaaaabbbbbbbbccccccccdddddddd, i64 1, i1 false)
@@ -74,7 +68,7 @@ define void @memset_pattern_i128_1_align_attr(ptr align(16) %a, i128 %value) nou
define void @memset_pattern_i128_16(ptr %a) nounwind {
; CHECK-LABEL: define void @memset_pattern_i128_16(
; CHECK-SAME: ptr [[A:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.9, i64 256)
+; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.4, i64 256)
; CHECK-NEXT: ret void
;
tail call void @llvm.experimental.memset.pattern(ptr %a, i128 u0xaaaaaaaabbbbbbbbccccccccdddddddd, i64 16, i1 false)
@@ -85,7 +79,7 @@ define void @memset_pattern_i128_x(ptr %a, i64 %x) nounwind {
; CHECK-LABEL: define void @memset_pattern_i128_x(
; CHECK-SAME: ptr [[A:%.*]], i64 [[X:%.*]]) #[[ATTR0]] {
; CHECK-NEXT: [[TMP1:%.*]] = mul i64 16, [[X]]
-; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.10, i64 [[TMP1]])
+; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.4, i64 [[TMP1]])
; CHECK-NEXT: ret void
;
tail call void @llvm.experimental.memset.pattern(ptr %a, i128 u0xaaaaaaaabbbbbbbbccccccccdddddddd, i64 %x, i1 false)
@@ -115,7 +109,7 @@ define void @memset_pattern_i16_x(ptr %a, i64 %x) nounwind {
; CHECK-LABEL: define void @memset_pattern_i16_x(
; CHECK-SAME: ptr [[A:%.*]], i64 [[X:%.*]]) #[[ATTR0]] {
; CHECK-NEXT: [[TMP1:%.*]] = mul i64 2, [[X]]
-; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.6, i64 [[TMP1]])
+; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.3, i64 [[TMP1]])
; CHECK-NEXT: ret void
;
tail call void @llvm.experimental.memset.pattern(ptr %a, i16 u0xabcd, i64 %x, i1 false)
@@ -126,7 +120,7 @@ define void @memset_pattern_i64_x(ptr %a, i64 %x) nounwind {
; CHECK-LABEL: define void @memset_pattern_i64_x(
; CHECK-SAME: ptr [[A:%.*]], i64 [[X:%.*]]) #[[ATTR0]] {
; CHECK-NEXT: [[TMP1:%.*]] = mul i64 8, [[X]]
-; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.4, i64 [[TMP1]])
+; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.1, i64 [[TMP1]])
; CHECK-NEXT: ret void
;
tail call void @llvm.experimental.memset.pattern(ptr %a, i64 u0xaaaabbbbccccdddd, i64 %x, i1 false)
@@ -137,7 +131,7 @@ define void @memset_pattern_i64_x(ptr %a, i64 %x) nounwind {
define void @memset_pattern_i64_128_tbaa(ptr %a) nounwind {
; CHECK-LABEL: define void @memset_pattern_i64_128_tbaa(
; CHECK-SAME: ptr [[A:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.5, i64 1024), !tbaa [[TBAA0:![0-9]+]]
+; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.2, i64 1024), !tbaa [[TBAA0:![0-9]+]]
; CHECK-NEXT: ret void
;
tail call void @llvm.experimental.memset.pattern(ptr %a, i64 u0x400921fb54442d18, i64 128, i1 false), !tbaa !5
@@ -154,7 +148,7 @@ define void @memset_pattern_i64_narrow_idx(ptr %a, i32 %x) nounwind {
; CHECK-SAME: ptr [[A:%.*]], i32 [[X:%.*]]) #[[ATTR0]] {
; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[X]] to i64
; CHECK-NEXT: [[TMP2:%.*]] = mul i64 8, [[TMP1]]
-; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.3, i64 [[TMP2]])
+; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.1, i64 [[TMP2]])
; CHECK-NEXT: ret void
;
tail call void @llvm.experimental.memset.pattern(ptr %a, i64 u0xaaaabbbbccccdddd, i32 %x, i1 false)
@@ -166,7 +160,7 @@ define void @memset_pattern_i64_wide_idx(ptr %a, i128 %x) nounwind {
; CHECK-SAME: ptr [[A:%.*]], i128 [[X:%.*]]) #[[ATTR0]] {
; CHECK-NEXT: [[TMP1:%.*]] = trunc i128 [[X]] to i64
; CHECK-NEXT: [[TMP2:%.*]] = mul i64 8, [[TMP1]]
-; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.2, i64 [[TMP2]])
+; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.1, i64 [[TMP2]])
; CHECK-NEXT: ret void
;
tail call void @llvm.experimental.memset.pattern(ptr %a, i64 u0xaaaabbbbccccdddd, i128 %x, i1 false)
@@ -189,7 +183,7 @@ define void @memset_pattern_i64_x_fromptr(ptr %a, i64 %x) nounwind {
; CHECK-LABEL: define void @memset_pattern_i64_x_fromptr(
; CHECK-SAME: ptr [[A:%.*]], i64 [[X:%.*]]) #[[ATTR0]] {
; CHECK-NEXT: [[TMP2:%.*]] = mul i64 8, [[X]]
-; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern.1, i64 [[TMP2]])
+; CHECK-NEXT: call void @memset_pattern16(ptr [[A]], ptr @.memset_pattern, i64 [[TMP2]])
; CHECK-NEXT: ret void
;
tail call void @llvm.experimental.memset.pattern(ptr %a, ptr @G, i64 %x, i1 false)
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