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

topperc · topperc · commit 1e413ffa7bc8 · 2019-04-24T06:48:31.000Z
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
diff --git a/llvm/include/llvm/CodeGen/MachineFunction.h b/llvm/include/llvm/CodeGen/MachineFunction.h
@@ -439,7 +439,6 @@ class MachineFunction {
   /// 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
@@ -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
@@ -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;

Original file line number	Diff line number	Diff line change
`@@ -204,8 +204,7 @@ MipsTargetMachine::getSubtargetImpl(const Function &F) const {`
`204`	`204`	`void MipsTargetMachine::resetSubtarget(MachineFunction *MF) {`
`205`	`205`	`LLVM_DEBUG(dbgs() << "resetSubtarget\n");`
`206`	`206`
`207`		`- Subtarget = const_cast<MipsSubtarget *>(getSubtargetImpl(MF->getFunction()));`
`208`		`- MF->setSubtarget(Subtarget);`
	`207`	`+ Subtarget = &MF->getSubtarget<MipsSubtarget>();`
`209`	`208`	`}`
`210`	`209`
`211`	`210`	`namespace {`