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Don't scan physreg use-def chains looking for a PIC base.

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We can't rematerialize a PIC base after register allocation anyway, and
scanning physreg use-def chains is very expensive in a function with
many calls.

<rdar://problem/12047515>

llvm-svn: 161461
This commit is contained in:
Jakob Stoklund Olesen 2012-08-08 00:40:47 +00:00
parent 10c3144381
commit 924ff06fdf
1 changed files with 4 additions and 10 deletions
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14
lib/Target/X86/X86InstrInfo.cpp
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@ -1463,6 +1463,9 @@ unsigned X86InstrInfo::isStoreToStackSlotPostFE(const MachineInstr *MI,
/// regIsPICBase - Return true if register is PIC base (i.e.g defined by
/// X86::MOVPC32r.
static bool regIsPICBase(unsigned BaseReg, const MachineRegisterInfo &MRI) {
// Don't waste compile time scanning use-def chains of physregs.
if (!TargetRegisterInfo::isVirtualRegister(BaseReg))
return false;
bool isPICBase = false;
for (MachineRegisterInfo::def_iterator I = MRI.def_begin(BaseReg),
E = MRI.def_end(); I != E; ++I) {
@ -1520,16 +1523,7 @@ X86InstrInfo::isReallyTriviallyReMaterializable(const MachineInstr *MI,
return false;
const MachineFunction &MF = *MI->getParent()->getParent();
const MachineRegisterInfo &MRI = MF.getRegInfo();
bool isPICBase = false;
for (MachineRegisterInfo::def_iterator I = MRI.def_begin(BaseReg),
E = MRI.def_end(); I != E; ++I) {
MachineInstr *DefMI = I.getOperand().getParent();
if (DefMI->getOpcode() != X86::MOVPC32r)
return false;
assert(!isPICBase && "More than one PIC base?");
isPICBase = true;
}
return isPICBase;
return regIsPICBase(BaseReg, MRI);
}
return false;
}