[llvm] r270246 - [X86] Reduce memory allocations in X86TargetMachine::getSubtargetImpl

[David Majnemer via llvm-commits]

Author: majnemer
Date: Fri May 20 13:16:06 2016
New Revision: 270246

URL: http://llvm.org/viewvc/llvm-project?rev=270246&view=rev
Log:
[X86] Reduce memory allocations in X86TargetMachine::getSubtargetImpl

We performed a number of memory allocations each time getTTI was called,
remove them by using SmallString.
No functionality change intended.

Modified:
    llvm/trunk/lib/Target/X86/X86Subtarget.cpp
    llvm/trunk/lib/Target/X86/X86Subtarget.h
    llvm/trunk/lib/Target/X86/X86TargetMachine.cpp

Modified: llvm/trunk/lib/Target/X86/X86Subtarget.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86Subtarget.cpp?rev=270246&r1=270245&r2=270246&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86Subtarget.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86Subtarget.cpp Fri May 20 13:16:06 2016
@@ -353,8 +353,8 @@ X86Subtarget &X86Subtarget::initializeSu
   return *this;
 }
 
-X86Subtarget::X86Subtarget(const Triple &TT, const std::string &CPU,
-                           const std::string &FS, const X86TargetMachine &TM,
+X86Subtarget::X86Subtarget(const Triple &TT, StringRef CPU, StringRef FS,
+                           const X86TargetMachine &TM,
                            unsigned StackAlignOverride)
     : X86GenSubtargetInfo(TT, CPU, FS), X86ProcFamily(Others),
       PICStyle(PICStyles::None), TM(TM), TargetTriple(TT),

Modified: llvm/trunk/lib/Target/X86/X86Subtarget.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86Subtarget.h?rev=270246&r1=270245&r2=270246&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86Subtarget.h (original)
+++ llvm/trunk/lib/Target/X86/X86Subtarget.h Fri May 20 13:16:06 2016
@@ -313,7 +313,7 @@ public:
   /// This constructor initializes the data members to match that
   /// of the specified triple.
   ///
-  X86Subtarget(const Triple &TT, const std::string &CPU, const std::string &FS,
+  X86Subtarget(const Triple &TT, StringRef CPU, StringRef FS,
                const X86TargetMachine &TM, unsigned StackAlignOverride);
 
   const X86TargetLowering *getTargetLowering() const override {

Modified: llvm/trunk/lib/Target/X86/X86TargetMachine.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86TargetMachine.cpp?rev=270246&r1=270245&r2=270246&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86TargetMachine.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86TargetMachine.cpp Fri May 20 13:16:06 2016
@@ -182,12 +182,12 @@ X86TargetMachine::getSubtargetImpl(const
   Attribute CPUAttr = F.getFnAttribute("target-cpu");
   Attribute FSAttr = F.getFnAttribute("target-features");
 
-  std::string CPU = !CPUAttr.hasAttribute(Attribute::None)
-                        ? CPUAttr.getValueAsString().str()
-                        : TargetCPU;
-  std::string FS = !FSAttr.hasAttribute(Attribute::None)
-                       ? FSAttr.getValueAsString().str()
-                       : TargetFS;
+  SmallString<32> CPU = !CPUAttr.hasAttribute(Attribute::None)
+                            ? CPUAttr.getValueAsString()
+                            : (StringRef)TargetCPU;
+  SmallString<512> FS = !FSAttr.hasAttribute(Attribute::None)
+                            ? FSAttr.getValueAsString()
+                            : (StringRef)TargetFS;
 
   // FIXME: This is related to the code below to reset the target options,
   // we need to know whether or not the soft float flag is set on the
@@ -201,7 +201,12 @@ X86TargetMachine::getSubtargetImpl(const
   if (SoftFloat)
     FS += FS.empty() ? "+soft-float" : ",+soft-float";
 
-  auto &I = SubtargetMap[CPU + FS];
+  SmallString<544> Key;
+  Key.reserve(CPU.size() + FS.size());
+  Key += CPU;
+  Key += FS;
+
+  auto &I = SubtargetMap[Key];
   if (!I) {
     // This needs to be done before we create a new subtarget since any
     // creation will depend on the TM and the code generation flags on the