[ARM][NFC] Avoid recreating MCSubtargetInfo in ARMAsmBackend

After D41349, we can now directly access MCSubtargetInfo from 
createARM*AsmBackend. This patch makes use of this, avoiding the need to 
create a fresh MCSubtargetInfo (which was previously always done with a blank 
CPU and feature string). Given the total size of the change remains pretty 
tiny and we're removing the old explicit destructor, I changed the STI field 
to a reference rather than a pointer.

Differential Revision: https://reviews.llvm.org/D41693

llvm-svn: 321707

6 files changed, 31 insertions, 36 deletions

diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
index 8552e62b652..ff507ab7162 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
@@ -172,8 +172,8 @@ void ARMAsmBackend::handleAssemblerFlag(MCAssemblerFlag Flag) {
 }
 
 unsigned ARMAsmBackend::getRelaxedOpcode(unsigned Op) const {
-  bool HasThumb2 = STI->getFeatureBits()[ARM::FeatureThumb2];
-  bool HasV8MBaselineOps = STI->getFeatureBits()[ARM::HasV8MBaselineOps];
+  bool HasThumb2 = STI.getFeatureBits()[ARM::FeatureThumb2];
+  bool HasV8MBaselineOps = STI.getFeatureBits()[ARM::HasV8MBaselineOps];
 
   switch (Op) {
   default:
@@ -389,7 +389,7 @@ unsigned ARMAsmBackend::adjustFixupValue(const MCAssembler &Asm,
   case FK_SecRel_4:
     return Value;
   case ARM::fixup_arm_movt_hi16:
-    if (IsResolved || !STI->getTargetTriple().isOSBinFormatELF())
+    if (IsResolved || !STI.getTargetTriple().isOSBinFormatELF())
       Value >>= 16;
     LLVM_FALLTHROUGH;
   case ARM::fixup_arm_movw_lo16: {
@@ -401,7 +401,7 @@ unsigned ARMAsmBackend::adjustFixupValue(const MCAssembler &Asm,
     return Value;
   }
   case ARM::fixup_t2_movt_hi16:
-    if (IsResolved || !STI->getTargetTriple().isOSBinFormatELF())
+    if (IsResolved || !STI.getTargetTriple().isOSBinFormatELF())
       Value >>= 16;
     LLVM_FALLTHROUGH;
   case ARM::fixup_t2_movw_lo16: {
@@ -591,7 +591,7 @@ unsigned ARMAsmBackend::adjustFixupValue(const MCAssembler &Asm,
   case ARM::fixup_arm_thumb_cp:
     // On CPUs supporting Thumb2, this will be relaxed to an ldr.w, otherwise we
     // could have an error on our hands.
-    if (!STI->getFeatureBits()[ARM::FeatureThumb2] && IsResolved) {
+    if (!STI.getFeatureBits()[ARM::FeatureThumb2] && IsResolved) {
       const char *FixupDiagnostic = reasonForFixupRelaxation(Fixup, Value);
       if (FixupDiagnostic) {
         Ctx.reportError(Fixup.getLoc(), FixupDiagnostic);
@@ -615,8 +615,8 @@ unsigned ARMAsmBackend::adjustFixupValue(const MCAssembler &Asm,
   }
   case ARM::fixup_arm_thumb_br:
     // Offset by 4 and don't encode the lower bit, which is always 0.
-    if (!STI->getFeatureBits()[ARM::FeatureThumb2] &&
-        !STI->getFeatureBits()[ARM::HasV8MBaselineOps]) {
+    if (!STI.getFeatureBits()[ARM::FeatureThumb2] &&
+        !STI.getFeatureBits()[ARM::HasV8MBaselineOps]) {
       const char *FixupDiagnostic = reasonForFixupRelaxation(Fixup, Value);
       if (FixupDiagnostic) {
         Ctx.reportError(Fixup.getLoc(), FixupDiagnostic);
@@ -626,7 +626,7 @@ unsigned ARMAsmBackend::adjustFixupValue(const MCAssembler &Asm,
     return ((Value - 4) >> 1) & 0x7ff;
   case ARM::fixup_arm_thumb_bcc:
     // Offset by 4 and don't encode the lower bit, which is always 0.
-    if (!STI->getFeatureBits()[ARM::FeatureThumb2]) {
+    if (!STI.getFeatureBits()[ARM::FeatureThumb2]) {
       const char *FixupDiagnostic = reasonForFixupRelaxation(Fixup, Value);
       if (FixupDiagnostic) {
         Ctx.reportError(Fixup.getLoc(), FixupDiagnostic);
@@ -1154,24 +1154,25 @@ static MachO::CPUSubTypeARM getMachOSubTypeFromArch(StringRef Arch) {
 }
 
 MCAsmBackend *llvm::createARMAsmBackend(const Target &T,
+                                        const MCSubtargetInfo &STI,
                                         const MCRegisterInfo &MRI,
-                                        const Triple &TheTriple, StringRef CPU,
                                         const MCTargetOptions &Options,
                                         bool isLittle) {
+  const Triple &TheTriple = STI.getTargetTriple();
   switch (TheTriple.getObjectFormat()) {
   default:
     llvm_unreachable("unsupported object format");
   case Triple::MachO: {
     MachO::CPUSubTypeARM CS = getMachOSubTypeFromArch(TheTriple.getArchName());
-    return new ARMAsmBackendDarwin(T, TheTriple, MRI, CS);
+    return new ARMAsmBackendDarwin(T, STI, MRI, CS);
   }
   case Triple::COFF:
     assert(TheTriple.isOSWindows() && "non-Windows ARM COFF is not supported");
-    return new ARMAsmBackendWinCOFF(T, TheTriple);
+    return new ARMAsmBackendWinCOFF(T, STI);
   case Triple::ELF:
     assert(TheTriple.isOSBinFormatELF() && "using ELF for non-ELF target");
     uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(TheTriple.getOS());
-    return new ARMAsmBackendELF(T, TheTriple, OSABI, isLittle);
+    return new ARMAsmBackendELF(T, STI, OSABI, isLittle);
   }
 }
 
@@ -1179,30 +1180,26 @@ MCAsmBackend *llvm::createARMLEAsmBackend(const Target &T,
                                           const MCSubtargetInfo &STI,
                                           const MCRegisterInfo &MRI,
                                           const MCTargetOptions &Options) {
-  return createARMAsmBackend(T, MRI, STI.getTargetTriple(), STI.getCPU(),
-                             Options, true);
+  return createARMAsmBackend(T, STI, MRI, Options, true);
 }
 
 MCAsmBackend *llvm::createARMBEAsmBackend(const Target &T,
                                           const MCSubtargetInfo &STI,
                                           const MCRegisterInfo &MRI,
                                           const MCTargetOptions &Options) {
-  return createARMAsmBackend(T, MRI, STI.getTargetTriple(), STI.getCPU(),
-                             Options, false);
+  return createARMAsmBackend(T, STI, MRI, Options, false);
 }
 
 MCAsmBackend *llvm::createThumbLEAsmBackend(const Target &T,
                                             const MCSubtargetInfo &STI,
                                             const MCRegisterInfo &MRI,
                                             const MCTargetOptions &Options) {
-  return createARMAsmBackend(T, MRI, STI.getTargetTriple(), STI.getCPU(),
-                             Options, true);
+  return createARMAsmBackend(T, STI, MRI, Options, true);
 }
 
 MCAsmBackend *llvm::createThumbBEAsmBackend(const Target &T,
                                             const MCSubtargetInfo &STI,
                                             const MCRegisterInfo &MRI,
                                             const MCTargetOptions &Options) {
-  return createARMAsmBackend(T, MRI, STI.getTargetTriple(), STI.getCPU(),
-                             Options, false);
+  return createARMAsmBackend(T, STI, MRI, Options, false);
 }
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.h b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.h
index 02374966daf..c8527e5cca2 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.h
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.h
@@ -19,22 +19,20 @@
 namespace llvm {
 
 class ARMAsmBackend : public MCAsmBackend {
-  const MCSubtargetInfo *STI;
+  const MCSubtargetInfo &STI;
   bool isThumbMode;    // Currently emitting Thumb code.
   bool IsLittleEndian; // Big or little endian.
 public:
-  ARMAsmBackend(const Target &T, const Triple &TT, bool IsLittle)
-      : MCAsmBackend(), STI(ARM_MC::createARMMCSubtargetInfo(TT, "", "")),
-        isThumbMode(TT.getArchName().startswith("thumb")),
+  ARMAsmBackend(const Target &T, const MCSubtargetInfo &STI, bool IsLittle)
+      : MCAsmBackend(), STI(STI),
+        isThumbMode(STI.getTargetTriple().isThumb()),
         IsLittleEndian(IsLittle) {}
 
-  ~ARMAsmBackend() override { delete STI; }
-
   unsigned getNumFixupKinds() const override {
     return ARM::NumTargetFixupKinds;
   }
 
-  bool hasNOP() const { return STI->getFeatureBits()[ARM::HasV6T2Ops]; }
+  bool hasNOP() const { return STI.getFeatureBits()[ARM::HasV6T2Ops]; }
 
   const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override;
 
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackendDarwin.h b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackendDarwin.h
index f05e3a6f116..19e3fdb7204 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackendDarwin.h
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackendDarwin.h
@@ -19,10 +19,10 @@ class ARMAsmBackendDarwin : public ARMAsmBackend {
   const MCRegisterInfo &MRI;
 public:
   const MachO::CPUSubTypeARM Subtype;
-  ARMAsmBackendDarwin(const Target &T, const Triple &TT,
+  ARMAsmBackendDarwin(const Target &T, const MCSubtargetInfo &STI,
                       const MCRegisterInfo &MRI, MachO::CPUSubTypeARM st)
-      : ARMAsmBackend(T, TT, /* IsLittleEndian */ true), MRI(MRI), Subtype(st) {
-  }
+      : ARMAsmBackend(T, STI, /* IsLittleEndian */ true), MRI(MRI),
+        Subtype(st) {}
 
   std::unique_ptr<MCObjectWriter>
   createObjectWriter(raw_pwrite_stream &OS) const override {
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackendELF.h b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackendELF.h
index d0f5419a1b0..361ea304084 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackendELF.h
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackendELF.h
@@ -20,9 +20,9 @@ namespace {
 class ARMAsmBackendELF : public ARMAsmBackend {
 public:
   uint8_t OSABI;
-  ARMAsmBackendELF(const Target &T, const Triple &TT, uint8_t OSABI,
+  ARMAsmBackendELF(const Target &T, const MCSubtargetInfo &STI, uint8_t OSABI,
                    bool IsLittle)
-      : ARMAsmBackend(T, TT, IsLittle), OSABI(OSABI) {}
+      : ARMAsmBackend(T, STI, IsLittle), OSABI(OSABI) {}
 
   std::unique_ptr<MCObjectWriter>
   createObjectWriter(raw_pwrite_stream &OS) const override {
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackendWinCOFF.h b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackendWinCOFF.h
index 53b9c29446a..0ac6d4270aa 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackendWinCOFF.h
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackendWinCOFF.h
@@ -17,8 +17,8 @@ using namespace llvm;
 namespace {
 class ARMAsmBackendWinCOFF : public ARMAsmBackend {
 public:
-  ARMAsmBackendWinCOFF(const Target &T, const Triple &TheTriple)
-      : ARMAsmBackend(T, TheTriple, true) {}
+  ARMAsmBackendWinCOFF(const Target &T, const MCSubtargetInfo &STI)
+      : ARMAsmBackend(T, STI, true) {}
   std::unique_ptr<MCObjectWriter>
   createObjectWriter(raw_pwrite_stream &OS) const override {
     return createARMWinCOFFObjectWriter(OS, /*Is64Bit=*/false);
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h
index 7ef72846368..df9874c78d0 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h
@@ -68,8 +68,8 @@ MCCodeEmitter *createARMBEMCCodeEmitter(const MCInstrInfo &MCII,
                                         const MCRegisterInfo &MRI,
                                         MCContext &Ctx);
 
-MCAsmBackend *createARMAsmBackend(const Target &T, const MCRegisterInfo &MRI,
-                                  const Triple &TT, StringRef CPU,
+MCAsmBackend *createARMAsmBackend(const Target &T, const MCSubtargetInfo &STI,
+                                  const MCRegisterInfo &MRI,
                                   const MCTargetOptions &Options,
                                   bool IsLittleEndian);