[InstrProf][X86] Mark non-directly accessed globals as large

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 llvm#74514.

This affects the __llvm_prf_vals, __llvm_prf_vnds, and __llvm_prf_names
sections.

Author: aeubanks

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();

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;
 }
 

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

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);
+  }
+}

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"