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To shrink a t2LDM instruction to the 16-bit wide tLDM instruction, the base 

register must be one of the destination registers for the load. Otherwise,
the tLDM instruction will write-back to the base register, which isn't what's
desired (otherwise, we'd have a t2LDM_UPD instead).

rdar://8394087

llvm-svn: 113297
This commit is contained in:
Jim Grosbach 2010-09-07 22:30:53 +00:00
parent 41994fd45d
commit 88628e9738
1 changed files with 12 additions and 0 deletions
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12
llvm/lib/Target/ARM/Thumb2SizeReduction.cpp
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@ -315,6 +315,18 @@ Thumb2SizeReduce::ReduceLoadStore(MachineBasicBlock &MBB, MachineInstr *MI,
ARM_AM::AMSubMode Mode = ARM_AM::getAM4SubMode(MI->getOperand(1).getImm());
if (!isARMLowRegister(BaseReg) || Mode != ARM_AM::ia)
return false;
// For the non-writeback version (this one), the base register must be
// one of the registers being loaded.
bool isOK = false;
for (unsigned i = 4; i < MI->getNumOperands(); ++i) {
if (MI->getOperand(i).getReg() == BaseReg) {
isOK = true;
break;
}
}
if (!isOK)
return false;
OpNum = 0;
isLdStMul = true;
break;