vitalybuka created this revision.
vitalybuka added reviewers: eugenis, pcc, jfb.
Herald added subscribers: cfe-commits, dexonsmith.
Herald added a project: clang.
In some cases llvm::getMostFrequentByte can't analyze a
constant so we write zeros and then override the rest with stores.
These zeros are not needed and we can keep only stores.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D64387
Files:
clang/lib/CodeGen/CGDecl.cpp
clang/test/CodeGen/init-memset.c
Index: clang/test/CodeGen/init-memset.c
===================================================================
--- clang/test/CodeGen/init-memset.c
+++ clang/test/CodeGen/init-memset.c
@@ -49,7 +49,7 @@
void test_pointers() {
// CHECK-LABEL: define void @test_pointers()
void *a[] = {&use, &use, &use, &use, &use, &use};
- // CHECK: call void @llvm.memset.{{.*}}
+ // CHECK-NOT: @llvm.memset.
// CHECK: store i8*
// CHECK: store i8*
// CHECK: store i8*
Index: clang/lib/CodeGen/CGDecl.cpp
===================================================================
--- clang/lib/CodeGen/CGDecl.cpp
+++ clang/lib/CodeGen/CGDecl.cpp
@@ -973,15 +973,10 @@
if (GlobalSize <= SizeLimit)
return nullptr;
- if (!MFB.Value) {
- // We don't know most frequent byte, we may still completely initialize it
- // with small number of stores.
- // TODO: Use llvm::UndefValue::get. If we get here and later we decide
- // that number of stores is small enough to use memset+store then store are
- // going to replace entire bzeroed range. With UndefValue we can skip that
- // bogus memset. I will do that as a separate patch.
- MFB.Value = llvm::ConstantInt::get(CGM.Int8Ty, 0);
- }
+ // We don't know most frequent byte, we may still completely initialize it
+ // with small number of stores.
+ if (!MFB.Value)
+ MFB.Value = llvm::UndefValue::get(CGM.Int8Ty);
unsigned StoreBudget = 6;
return canEmitStoresForInitAfterMemset(CGM, Init, MFB.Value, StoreBudget)
Index: clang/test/CodeGen/init-memset.c
===================================================================
--- clang/test/CodeGen/init-memset.c
+++ clang/test/CodeGen/init-memset.c
@@ -49,7 +49,7 @@
void test_pointers() {
// CHECK-LABEL: define void @test_pointers()
void *a[] = {&use, &use, &use, &use, &use, &use};
- // CHECK: call void @llvm.memset.{{.*}}
+ // CHECK-NOT: @llvm.memset.
// CHECK: store i8*
// CHECK: store i8*
// CHECK: store i8*
Index: clang/lib/CodeGen/CGDecl.cpp
===================================================================
--- clang/lib/CodeGen/CGDecl.cpp
+++ clang/lib/CodeGen/CGDecl.cpp
@@ -973,15 +973,10 @@
if (GlobalSize <= SizeLimit)
return nullptr;
- if (!MFB.Value) {
- // We don't know most frequent byte, we may still completely initialize it
- // with small number of stores.
- // TODO: Use llvm::UndefValue::get. If we get here and later we decide
- // that number of stores is small enough to use memset+store then store are
- // going to replace entire bzeroed range. With UndefValue we can skip that
- // bogus memset. I will do that as a separate patch.
- MFB.Value = llvm::ConstantInt::get(CGM.Int8Ty, 0);
- }
+ // We don't know most frequent byte, we may still completely initialize it
+ // with small number of stores.
+ if (!MFB.Value)
+ MFB.Value = llvm::UndefValue::get(CGM.Int8Ty);
unsigned StoreBudget = 6;
return canEmitStoresForInitAfterMemset(CGM, Init, MFB.Value, StoreBudget)
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