[llvm] [InstrProf][X86] Mark non-directly accessed globals as large (PR #74778)
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Thu Dec 7 15:01:58 PST 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-compiler-rt-sanitizer
@llvm/pr-subscribers-llvm-transforms
Author: Arthur Eubanks (aeubanks)
<details>
<summary>Changes</summary>
We'd like to make various instrprof globals large to make them not
contribute to relocation pressure since there are no direct accesses
to them in the module.
Similar to what was done for asan_globals in #<!-- -->74514.
This affects the __llvm_prf_vals, __llvm_prf_vnds, and __llvm_prf_names
sections.
---
Full diff: https://github.com/llvm/llvm-project/pull/74778.diff
5 Files Affected:
- (modified) llvm/include/llvm/Transforms/Instrumentation.h (+5)
- (modified) llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp (+1-3)
- (modified) llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp (+4)
- (modified) llvm/lib/Transforms/Instrumentation/Instrumentation.cpp (+7)
- (modified) llvm/test/Instrumentation/InstrProfiling/icall-comdat.ll (+18-5)
``````````diff
diff --git a/llvm/include/llvm/Transforms/Instrumentation.h b/llvm/include/llvm/Transforms/Instrumentation.h
index 3035cdeeacf68..0e97b7d8de3ad 100644
--- a/llvm/include/llvm/Transforms/Instrumentation.h
+++ b/llvm/include/llvm/Transforms/Instrumentation.h
@@ -49,6 +49,11 @@ GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
// Returns nullptr on failure.
Comdat *getOrCreateFunctionComdat(Function &F, Triple &T);
+// Place global in a large section for x86-64 ELF binaries to mitigate
+// relocation pressure. Should typically be used for metadata globals that
+// aren't directly accessed in the module.
+void setGlobalVariableLargeSection(Triple &TargetTriple, GlobalVariable &GV);
+
// Insert GCOV profiling instrumentation
struct GCOVOptions {
static GCOVOptions getDefault();
diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 3a3b41f5dc87d..b175e6f93f3e8 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -2146,9 +2146,7 @@ ModuleAddressSanitizer::CreateMetadataGlobal(Module &M, Constant *Initializer,
Metadata->setSection(getGlobalMetadataSection());
// Place metadata in a large section for x86-64 ELF binaries to mitigate
// relocation pressure.
- if (TargetTriple.getArch() == Triple::x86_64 &&
- TargetTriple.getObjectFormat() == Triple::ELF)
- Metadata->setCodeModel(CodeModel::Large);
+ setGlobalVariableLargeSection(TargetTriple, *Metadata);
return Metadata;
}
diff --git a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
index 10258e2546791..d3282779d9f5f 100644
--- a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -49,6 +49,7 @@
#include "llvm/Support/Error.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/TargetParser/Triple.h"
+#include "llvm/Transforms/Instrumentation.h"
#include "llvm/Transforms/Instrumentation/PGOInstrumentation.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
@@ -1294,6 +1295,7 @@ void InstrProfiling::createDataVariable(InstrProfCntrInstBase *Inc) {
*M, ValuesTy, false, Linkage, Constant::getNullValue(ValuesTy),
getVarName(Inc, getInstrProfValuesVarPrefix(), Renamed));
ValuesVar->setVisibility(Visibility);
+ setGlobalVariableLargeSection(TT, *ValuesVar);
ValuesVar->setSection(
getInstrProfSectionName(IPSK_vals, TT.getObjectFormat()));
ValuesVar->setAlignment(Align(8));
@@ -1422,6 +1424,7 @@ void InstrProfiling::emitVNodes() {
auto *VNodesVar = new GlobalVariable(
*M, VNodesTy, false, GlobalValue::PrivateLinkage,
Constant::getNullValue(VNodesTy), getInstrProfVNodesVarName());
+ setGlobalVariableLargeSection(TT, *VNodesVar);
VNodesVar->setSection(
getInstrProfSectionName(IPSK_vnodes, TT.getObjectFormat()));
VNodesVar->setAlignment(M->getDataLayout().getABITypeAlign(VNodesTy));
@@ -1449,6 +1452,7 @@ void InstrProfiling::emitNameData() {
GlobalValue::PrivateLinkage, NamesVal,
getInstrProfNamesVarName());
NamesSize = CompressedNameStr.size();
+ setGlobalVariableLargeSection(TT, *NamesVar);
NamesVar->setSection(
getInstrProfSectionName(IPSK_name, TT.getObjectFormat()));
// On COFF, it's important to reduce the alignment down to 1 to prevent the
diff --git a/llvm/lib/Transforms/Instrumentation/Instrumentation.cpp b/llvm/lib/Transforms/Instrumentation/Instrumentation.cpp
index 806afc8fcdf7c..199afbe966dde 100644
--- a/llvm/lib/Transforms/Instrumentation/Instrumentation.cpp
+++ b/llvm/lib/Transforms/Instrumentation/Instrumentation.cpp
@@ -85,3 +85,10 @@ Comdat *llvm::getOrCreateFunctionComdat(Function &F, Triple &T) {
return C;
}
+void llvm::setGlobalVariableLargeSection(Triple &TargetTriple,
+ GlobalVariable &GV) {
+ if (TargetTriple.getArch() == Triple::x86_64 &&
+ TargetTriple.getObjectFormat() == Triple::ELF) {
+ GV.setCodeModel(CodeModel::Large);
+ }
+}
diff --git a/llvm/test/Instrumentation/InstrProfiling/icall-comdat.ll b/llvm/test/Instrumentation/InstrProfiling/icall-comdat.ll
index c90f37c820895..502cef8a73a0e 100644
--- a/llvm/test/Instrumentation/InstrProfiling/icall-comdat.ll
+++ b/llvm/test/Instrumentation/InstrProfiling/icall-comdat.ll
@@ -1,5 +1,4 @@
;; Check that static counters are allocated for value profiler
-
; RUN: opt < %s -mtriple=x86_64-unknown-linux -passes=instrprof -vp-static-alloc=true -S | FileCheck %s --check-prefix=STATIC
; RUN: opt < %s -mtriple=powerpc-unknown-linux -passes=instrprof -vp-static-alloc=true -S | FileCheck %s --check-prefix=STATIC
; RUN: opt < %s -mtriple=sparc-unknown-linux -passes=instrprof -vp-static-alloc=true -S | FileCheck %s --check-prefix=STATIC
@@ -16,6 +15,10 @@
; RUN: opt %s -mtriple=powerpc64-ibm-aix -passes=instrprof -S | FileCheck %s --check-prefix=ALIGN
; RUN: opt %s -mtriple=x86_64-unknown-linux -passes=instrprof -S | FileCheck %s --check-prefix=ALIGN
+;; Check that globals have the proper code model.
+; RUN: opt %s -mtriple=x86_64-unknown-linux -passes=instrprof -S | FileCheck %s --check-prefix=X8664-CODEMODEL
+; RUN: opt %s -mtriple=powerpc-unknown-linux -passes=instrprof -S | FileCheck %s --check-prefix=PPC-CODEMODEL
+
@__profn_foo = private constant [3 x i8] c"foo"
@__profn_bar = private constant [3 x i8] c"bar"
@@ -46,8 +49,8 @@ declare void @llvm.instrprof.value.profile(ptr, i64, i64, i32, i32) #0
attributes #0 = { nounwind }
-; STATIC: @__profvp_foo = private global [1 x i64] zeroinitializer, section "{{[^"]+}}", comdat($__profc_foo)
-; STATIC: @__profvp_bar = private global [1 x i64] zeroinitializer, section "{{[^"]+}}", comdat($__profc_bar)
+; STATIC: @__profvp_foo = private global [1 x i64] zeroinitializer, section "{{[^"]+}}",{{.*}} comdat($__profc_foo)
+; STATIC: @__profvp_bar = private global [1 x i64] zeroinitializer, section "{{[^"]+}}",{{.*}} comdat($__profc_bar)
; STATIC: @__llvm_prf_vnodes
; DYN-NOT: @__profvp_foo
@@ -73,5 +76,15 @@ attributes #0 = { nounwind }
; ALIGN: @__profc_bar = private global {{.*}} section "__llvm_prf_cnts",{{.*}} align 8
; ALIGN: @__profvp_bar = private global {{.*}} section "__llvm_prf_vals",{{.*}} align 8
; ALIGN: @__profd_bar = private global {{.*}} section "__llvm_prf_data",{{.*}} align 8
-; ALIGN: @__llvm_prf_vnodes = private global {{.*}} section "__llvm_prf_vnds", align 8
-; ALIGN: @__llvm_prf_nm = private constant {{.*}} section "__llvm_prf_names", align 1
+; ALIGN: @__llvm_prf_vnodes = private global {{.*}} section "__llvm_prf_vnds",{{.*}} align 8
+; ALIGN: @__llvm_prf_nm = private constant {{.*}} section "__llvm_prf_names",{{.*}} align 1
+
+; X8664-CODEMODEL-NOT: @__profc_foo = {{.*}}, code_model "large"
+; X8664-CODEMODEL: @__profvp_foo = {{.*}}, code_model "large"
+; X8664-CODEMODEL-NOT: @__profd_foo = {{.*}}, code_model "large"
+; X8664-CODEMODEL-NOT: @__profc_bar = {{.*}}, code_model "large"
+; X8664-CODEMODEL: @__profvp_bar = {{.*}}, code_model "large"
+; X8664-CODEMODEL-NOT: @__profd_bar = {{.*}}, code_model "large"
+; X8664-CODEMODEL: @__llvm_prf_vnodes = {{.*}}, code_model "large"
+; X8664-CODEMODEL: @__llvm_prf_nm = {{.*}}, code_model "large"
+; PPC-CODEMODEL-NOT: code_model "large"
``````````
</details>
https://github.com/llvm/llvm-project/pull/74778
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