Reland [InstrProf][X86] Mark non-directly accessed globals as large (#74778)

aeubanks · aeubanks · commit 66b919cb2949 · 2023-12-08T09:54:57.000-08:00
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. The reland fixes platform.ll.
diff --git 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 overflow pressure. This can be be used for metadata globals that
+// aren't directly accessed by code, which has no performance impact.
+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
@@ -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
@@ -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
@@ -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
@@ -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-prefixes=CODEMODEL,CODEMODEL-X8664
+; RUN: opt %s -mtriple=powerpc-unknown-linux -passes=instrprof -S | FileCheck %s --check-prefixes=CODEMODEL,CODEMODEL-PPC
+
 @__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 +76,26 @@ 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
+
+; CODEMODEL: @__profc_foo =
+; CODEMODEL-NOT: code_model "large"
+; CODEMODEL: @__profvp_foo =
+; CODEMODEL-X8664-SAME: code_model "large"
+; CODEMODEL-PPC-NOT: code_model
+; CODEMODEL: @__profd_foo =
+; CODEMODEL-NOT: code_model "large"
+; CODEMODEL: @__profc_bar =
+; CODEMODEL-NOT: code_model "large"
+; CODEMODEL: @__profvp_bar =
+; CODEMODEL-X8664-SAME: code_model "large"
+; CODEMODEL-PPC-NOT: code_model
+; CODEMODEL: @__profd_bar =
+; CODEMODEL-NOT: code_model "large"
+; CODEMODEL: @__llvm_prf_vnodes =
+; CODEMODEL-X8664-SAME: code_model "large"
+; CODEMODEL-PPC-NOT: code_model
+; CODEMODEL: @__llvm_prf_nm =
+; CODEMODEL-X8664-SAME: code_model "large"
+; CODEMODEL-PPC-NOT: code_model
diff --git a/llvm/test/Instrumentation/InstrProfiling/platform.ll b/llvm/test/Instrumentation/InstrProfiling/platform.ll
@@ -25,7 +25,7 @@
 ; WINDOWS: @__profd_foo = private global {{.*}}, section ".lprfd$M", align 8
 ; AIX: @__profd_foo = private {{.*}}, section "__llvm_prf_data", align 8
 
-; ELF: @__llvm_prf_nm = private constant [{{.*}} x i8] c"{{.*}}", section "{{.*}}__llvm_prf_names", align 1
+; ELF: @__llvm_prf_nm = private constant [{{.*}} x i8] c"{{.*}}", section "{{.*}}__llvm_prf_names"{{.*}}, align 1
 ; WINDOWS: @__llvm_prf_nm = private constant [{{.*}} x i8] c"{{.*}}", section "{{.*}}lprfn$M", align 1
 ; AIX: @__llvm_prf_nm = private constant [{{.*}} x i8] c"{{.*}}", section "{{.*}}__llvm_prf_names", align 1
 
