CodeGen, Target: Move Mach-O-specific symbol name logic to Mach-O lowering.

A profile of an LTO link of Chrome revealed that we were spending some
~30-50% of execution time in the function Constant::getRelocationInfo(),
which is called from TargetLoweringObjectFile::getKindForGlobal() and in turn
from TargetMachine::getNameWithPrefix().

It turns out that we only need the result of getKindForGlobal() when
targeting Mach-O, so this change moves the relevant part of the logic to
TargetLoweringObjectFileMachO.

NFCI.

Differential Revision: http://reviews.llvm.org/D14168

llvm-svn: 252014

llvm/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h

@@ -123,6 +123,9 @@ public:
                                           const MCValue &MV, int64_t Offset,
                                           MachineModuleInfo *MMI,
                                           MCStreamer &Streamer) const override;
+
+  void getNameWithPrefix(SmallVectorImpl<char> &OutName, const GlobalValue *GV,
+                         Mangler &Mang, const TargetMachine &TM) const override;
 };
 
 
@@ -140,8 +143,7 @@ public:
                                     const TargetMachine &TM) const override;
 
   void getNameWithPrefix(SmallVectorImpl<char> &OutName, const GlobalValue *GV,
-                         bool CannotUsePrivateLabel, Mangler &Mang,
+                         Mangler &Mang, const TargetMachine &TM) const override;
-                         const TargetMachine &TM) const override;
 
   MCSection *getSectionForJumpTable(const Function &F, Mangler &Mang,
                                     const TargetMachine &TM) const override;

llvm/include/llvm/Target/TargetLoweringObjectFile.h

@@ -93,8 +93,7 @@ public:
   }
 
   virtual void getNameWithPrefix(SmallVectorImpl<char> &OutName,
-                                 const GlobalValue *GV,
+                                 const GlobalValue *GV, Mangler &Mang,
-                                 bool CannotUsePrivateLabel, Mangler &Mang,
                                  const TargetMachine &TM) const;
 
   virtual MCSection *getSectionForJumpTable(const Function &F, Mangler &Mang,

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -24,6 +24,7 @@
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/Mangler.h"
 #include "llvm/IR/Module.h"
+#include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCSectionCOFF.h"
@@ -763,6 +764,29 @@ const MCExpr *TargetLoweringObjectFileMachO::getIndirectSymViaGOTPCRel(
   return MCBinaryExpr::createSub(LHS, RHS, Ctx);
 }
 
+static bool canUsePrivateLabel(const MCAsmInfo &AsmInfo,
+                               const MCSection &Section) {
+  if (!AsmInfo.isSectionAtomizableBySymbols(Section))
+    return true;
+
+  // If it is not dead stripped, it is safe to use private labels.
+  const MCSectionMachO &SMO = cast<MCSectionMachO>(Section);
+  if (SMO.hasAttribute(MachO::S_ATTR_NO_DEAD_STRIP))
+    return true;
+
+  return false;
+}
+
+void TargetLoweringObjectFileMachO::getNameWithPrefix(
+    SmallVectorImpl<char> &OutName, const GlobalValue *GV, Mangler &Mang,
+    const TargetMachine &TM) const {
+  SectionKind GVKind = TargetLoweringObjectFile::getKindForGlobal(GV, TM);
+  const MCSection *TheSection = SectionForGlobal(GV, GVKind, Mang, TM);
+  bool CannotUsePrivateLabel =
+      !canUsePrivateLabel(*TM.getMCAsmInfo(), *TheSection);
+  Mang.getNameWithPrefix(OutName, GV, CannotUsePrivateLabel);
+}
+
 //===----------------------------------------------------------------------===//
 //                                  COFF
 //===----------------------------------------------------------------------===//
@@ -918,7 +942,7 @@ MCSection *TargetLoweringObjectFileCOFF::SelectSectionForGlobal(
                                          COMDATSymName, Selection);
     } else {
       SmallString<256> TmpData;
-      getNameWithPrefix(TmpData, GV, /*CannotUsePrivateLabel=*/true, Mang, TM);
+      Mang.getNameWithPrefix(TmpData, GV, /*CannotUsePrivateLabel=*/true);
       return getContext().getCOFFSection(Name, Characteristics, Kind, TmpData,
                                          Selection);
     }
@@ -943,8 +967,9 @@ MCSection *TargetLoweringObjectFileCOFF::SelectSectionForGlobal(
 }
 
 void TargetLoweringObjectFileCOFF::getNameWithPrefix(
-    SmallVectorImpl<char> &OutName, const GlobalValue *GV,
+    SmallVectorImpl<char> &OutName, const GlobalValue *GV, Mangler &Mang,
-    bool CannotUsePrivateLabel, Mangler &Mang, const TargetMachine &TM) const {
+    const TargetMachine &TM) const {
+  bool CannotUsePrivateLabel = false;
   if (GV->hasPrivateLinkage() &&
       ((isa<Function>(GV) && TM.getFunctionSections()) ||
        (isa<GlobalVariable>(GV) && TM.getDataSections())))

llvm/lib/Target/TargetLoweringObjectFile.cpp

@@ -344,7 +344,7 @@ const MCExpr *TargetLoweringObjectFile::getDebugThreadLocalSymbol(const MCSymbol
 }
 
 void TargetLoweringObjectFile::getNameWithPrefix(
-    SmallVectorImpl<char> &OutName, const GlobalValue *GV,
+    SmallVectorImpl<char> &OutName, const GlobalValue *GV, Mangler &Mang,
-    bool CannotUsePrivateLabel, Mangler &Mang, const TargetMachine &TM) const {
+    const TargetMachine &TM) const {
-  Mang.getNameWithPrefix(OutName, GV, CannotUsePrivateLabel);
+  Mang.getNameWithPrefix(OutName, GV, /*CannotUsePrivateLabel=*/false);
 }

llvm/lib/Target/TargetMachine.cpp

@@ -155,19 +155,6 @@ TargetIRAnalysis TargetMachine::getTargetIRAnalysis() {
   });
 }
 
-static bool canUsePrivateLabel(const MCAsmInfo &AsmInfo,
-                               const MCSection &Section) {
-  if (!AsmInfo.isSectionAtomizableBySymbols(Section))
-    return true;
-
-  // If it is not dead stripped, it is safe to use private labels.
-  const MCSectionMachO &SMO = cast<MCSectionMachO>(Section);
-  if (SMO.hasAttribute(MachO::S_ATTR_NO_DEAD_STRIP))
-    return true;
-
-  return false;
-}
-
 void TargetMachine::getNameWithPrefix(SmallVectorImpl<char> &Name,
                                       const GlobalValue *GV, Mangler &Mang,
                                       bool MayAlwaysUsePrivate) const {
@@ -177,11 +164,8 @@ void TargetMachine::getNameWithPrefix(SmallVectorImpl<char> &Name,
     Mang.getNameWithPrefix(Name, GV, false);
     return;
   }
-  SectionKind GVKind = TargetLoweringObjectFile::getKindForGlobal(GV, *this);
   const TargetLoweringObjectFile *TLOF = getObjFileLowering();
-  const MCSection *TheSection = TLOF->SectionForGlobal(GV, GVKind, Mang, *this);
+  TLOF->getNameWithPrefix(Name, GV, Mang, *this);
-  bool CannotUsePrivateLabel = !canUsePrivateLabel(*AsmInfo, *TheSection);
-  TLOF->getNameWithPrefix(Name, GV, CannotUsePrivateLabel, Mang, *this);
 }
 
 MCSymbol *TargetMachine::getSymbol(const GlobalValue *GV, Mangler &Mang) const {