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Add a floating point killer pass. This pass runs before register

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allocaton on the X86 to add information to the machine code denoting
that our floating point stackifier cannot handle virtual point
register that are alive across basic blocks. This pass adds an
implicit def of all virtual floating point register at the end of each
basic block.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10446 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alkis Evlogimenos
2003-12-13 05:36:22 +00:00
parent 9435eda699
commit 359b65f782
4 changed files with 120 additions and 0 deletions
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52
lib/Target/X86/X86FloatingPoint.cpp
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@ -18,6 +18,7 @@
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/LiveVariables.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "Support/Debug.h"
@ -601,4 +602,55 @@ void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) {
I = MBB->erase(I)-1; // Remove the pseudo instruction
}
namespace {
struct FPK : public MachineFunctionPass {
virtual const char *getPassName() const { return "X86 FP Killer"; }
virtual bool runOnMachineFunction(MachineFunction &MF);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<LiveVariables>();
AU.addRequiredID(PHIEliminationID);
MachineFunctionPass::getAnalysisUsage(AU);
}
};
}
FunctionPass * createX86FloatingPointKillerPass() { return new FPK(); }
bool FPK::runOnMachineFunction(MachineFunction &MF)
{
const TargetInstrInfo& tii = MF.getTarget().getInstrInfo();;
for (MachineFunction::iterator
mbbi = MF.begin(), mbbe = MF.end(); mbbi != mbbe; ++mbbi) {
MachineBasicBlock& mbb = *mbbi;
MachineBasicBlock::reverse_iterator mii = mbb.rbegin();
// rewind to the last non terminating instruction
while (mii != mbb.rend() && tii.isTerminatorInstr((*mii)->getOpcode())) {
++mii;
}
// add implicit def for all virtual floating point registers so that
// they are spilled at the end of each basic block, since our
// register stackifier doesn't handle them otherwise.
MachineInstr* instr = BuildMI(X86::IMPLICIT_DEF, 7)
.addReg(X86::FP6, MOTy::Def)
.addReg(X86::FP5, MOTy::Def)
.addReg(X86::FP4, MOTy::Def)
.addReg(X86::FP3, MOTy::Def)
.addReg(X86::FP2, MOTy::Def)
.addReg(X86::FP1, MOTy::Def)
.addReg(X86::FP0, MOTy::Def);
mbb.insert(mii.base(), instr);
LiveVariables& lv = getAnalysis<LiveVariables>();
for (unsigned i = 0; i < instr->getNumOperands(); ++i) {
lv.HandlePhysRegDef(instr->getOperand(i).getAllocatedRegNum(), instr);
// force live variables to compute that these registers are dead
lv.HandlePhysRegDef(instr->getOperand(i).getAllocatedRegNum(), 0);
}
}
return true;
}
} // End llvm namespace