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Simplify RegScavenger::FindUnusedReg.

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- Drop the Candidates argument and fix all callers. Now that RegScavenger
  tracks available registers accurately, there is no need to restict the
  search.
- Make sure that no aliases of the found register are in use. This was a potential bug.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79369 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2009-08-18 21:14:54 +00:00
parent 1123135dbf
commit c0823fe7c6
6 changed files with 13 additions and 51 deletions
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36
lib/CodeGen/RegisterScavenging.cpp
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@@ -248,36 +248,12 @@ static void CreateRegClassMask(const TargetRegisterClass *RC, BitVector &Mask) {
Mask.set(*I);
}
unsigned RegScavenger::FindUnusedReg(const TargetRegisterClass *RegClass,
const BitVector &Candidates) const {
// Mask off the registers which are not in the TargetRegisterClass.
BitVector RegsAvailableCopy(NumPhysRegs, false);
CreateRegClassMask(RegClass, RegsAvailableCopy);
RegsAvailableCopy &= RegsAvailable;
// Restrict the search to candidates.
RegsAvailableCopy &= Candidates;
// Returns the first unused (bit is set) register, or 0 is none is found.
int Reg = RegsAvailableCopy.find_first();
return (Reg == -1) ? 0 : Reg;
}
unsigned RegScavenger::FindUnusedReg(const TargetRegisterClass *RegClass,
bool ExCalleeSaved) const {
// Mask off the registers which are not in the TargetRegisterClass.
BitVector RegsAvailableCopy(NumPhysRegs, false);
CreateRegClassMask(RegClass, RegsAvailableCopy);
RegsAvailableCopy &= RegsAvailable;
// If looking for a non-callee-saved register, mask off all the callee-saved
// registers.
if (ExCalleeSaved)
RegsAvailableCopy &= ~CalleeSavedRegs;
// Returns the first unused (bit is set) register, or 0 is none is found.
int Reg = RegsAvailableCopy.find_first();
return (Reg == -1) ? 0 : Reg;
unsigned RegScavenger::FindUnusedReg(const TargetRegisterClass *RC) const {
for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end();
I != E; ++I)
if (!isAliasUsed(*I))
return *I;
return 0;
}
/// findSurvivorReg - Return the candidate register that is unused for the