[Mips][CodeGen] Remove MachineFunction::setSubtarget. Change Mips to just copy the subtarget from the MachineFunction instead of recalculating it.

Summary:
The MachineFunction should have been created with the correct subtarget. As
long as there is no way to change it, MipsTargetMachine can just capture it
directly from the MachineFunction without calling getSubtargetImpl again.

While there, const correct the Subtarget pointer to avoid a const_cast.

I believe the Mips16Subtarget and NoMips16Subtarget members are never used, but
I'll leave there removal for a separate patch.

Reviewers: echristo, atanasyan

Reviewed By: atanasyan

Subscribers: sdardis, arichardson, hiraditya, jrtc27, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60936

llvm-svn: 359071

3 files changed, 2 insertions, 4 deletions

diff --git a/llvm/include/llvm/CodeGen/MachineFunction.h b/llvm/include/llvm/CodeGen/MachineFunction.h
index 3d07c49cb64..65fa72b2793 100644
--- a/llvm/include/llvm/CodeGen/MachineFunction.h
+++ b/llvm/include/llvm/CodeGen/MachineFunction.h
@@ -439,7 +439,6 @@ public:
   /// getSubtarget - Return the subtarget for which this machine code is being
   /// compiled.
   const TargetSubtargetInfo &getSubtarget() const { return *STI; }
-  void setSubtarget(const TargetSubtargetInfo *ST) { STI = ST; }
 
   /// getSubtarget - This method returns a pointer to the specified type of
   /// TargetSubtargetInfo.  In debug builds, it verifies that the object being
diff --git a/llvm/lib/Target/Mips/MipsTargetMachine.cpp b/llvm/lib/Target/Mips/MipsTargetMachine.cpp
index 591e2c4b706..83094618ba0 100644
--- a/llvm/lib/Target/Mips/MipsTargetMachine.cpp
+++ b/llvm/lib/Target/Mips/MipsTargetMachine.cpp
@@ -204,8 +204,7 @@ MipsTargetMachine::getSubtargetImpl(const Function &F) const {
 void MipsTargetMachine::resetSubtarget(MachineFunction *MF) {
   LLVM_DEBUG(dbgs() << "resetSubtarget\n");
 
-  Subtarget = const_cast<MipsSubtarget *>(getSubtargetImpl(MF->getFunction()));
-  MF->setSubtarget(Subtarget);
+  Subtarget = &MF->getSubtarget<MipsSubtarget>();
 }
 
 namespace {
diff --git a/llvm/lib/Target/Mips/MipsTargetMachine.h b/llvm/lib/Target/Mips/MipsTargetMachine.h
index a51f35511b5..25300504a02 100644
--- a/llvm/lib/Target/Mips/MipsTargetMachine.h
+++ b/llvm/lib/Target/Mips/MipsTargetMachine.h
@@ -29,7 +29,7 @@ class MipsTargetMachine : public LLVMTargetMachine {
   std::unique_ptr<TargetLoweringObjectFile> TLOF;
   // Selected ABI
   MipsABIInfo ABI;
-  MipsSubtarget *Subtarget;
+  const MipsSubtarget *Subtarget;
   MipsSubtarget DefaultSubtarget;
   MipsSubtarget NoMips16Subtarget;
   MipsSubtarget Mips16Subtarget;