6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-01-01 00:33:09 +00:00
Code Issues Projects Releases Wiki Activity

When checking if something's killed, don't rely simply on whether it's marked as

Browse Source 
"used outside of the block". If the block ends in a return, then it won't be
used outside of it.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98599 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2010-03-16 01:05:35 +00:00
parent 5f19c43161
commit 8fe347a8b5
1 changed files with 15 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
lib/CodeGen/RegAllocLocal.cpp
View File

@ -671,7 +671,8 @@ void RALocal::ComputeLocalLiveness(MachineBasicBlock& MBB) {
// Live-out (of the function) registers contain return values of the function,
// so we need to make sure they are alive at return time.
if (!MBB.empty() && MBB.back().getDesc().isReturn()) {
bool BBEndsInReturn = !MBB.empty() && MBB.back().getDesc().isReturn();
if (BBEndsInReturn) {
MachineInstr* Ret = &MBB.back();
for (MachineRegisterInfo::liveout_iterator
I = MF->getRegInfo().liveout_begin(),
@ -696,7 +697,10 @@ void RALocal::ComputeLocalLiveness(MachineBasicBlock& MBB) {
bool usedOutsideBlock = isPhysReg ? false :
UsedInMultipleBlocks.test(MO.getReg() -
TargetRegisterInfo::FirstVirtualRegister);
if (!isPhysReg && !usedOutsideBlock) {
// If the machine BB ends in a return instruction, then the value isn't used
// outside of the BB.
if (!isPhysReg && (!usedOutsideBlock || BBEndsInReturn)) {
// DBG_VALUE complicates this: if the only refs of a register outside
// this block are DBG_VALUE, we can't keep the reg live just for that,
// as it will cause the reg to be spilled at the end of this block when
@ -704,7 +708,7 @@ void RALocal::ComputeLocalLiveness(MachineBasicBlock& MBB) {
// happens.
bool UsedByDebugValueOnly = false;
for (MachineRegisterInfo::reg_iterator UI = MRI.reg_begin(MO.getReg()),
UE = MRI.reg_end(); UI != UE; ++UI)
UE = MRI.reg_end(); UI != UE; ++UI) {
// Two cases:
// - used in another block
// - used in the same block before it is defined (loop)
@ -714,6 +718,7 @@ void RALocal::ComputeLocalLiveness(MachineBasicBlock& MBB) {
UsedByDebugValueOnly = true;
continue;
}
// A non-DBG_VALUE use means we can leave DBG_VALUE uses alone.
UsedInMultipleBlocks.set(MO.getReg() -
TargetRegisterInfo::FirstVirtualRegister);
@ -721,6 +726,8 @@ void RALocal::ComputeLocalLiveness(MachineBasicBlock& MBB) {
UsedByDebugValueOnly = false;
break;
}
}
if (UsedByDebugValueOnly)
for (MachineRegisterInfo::reg_iterator UI = MRI.reg_begin(MO.getReg()),
UE = MRI.reg_end(); UI != UE; ++UI)
@ -730,16 +737,16 @@ void RALocal::ComputeLocalLiveness(MachineBasicBlock& MBB) {
UI.getOperand().setReg(0U);
}
// Physical registers and those that are not live-out of the block
// are killed/dead at their last use/def within this block.
if (isPhysReg || !usedOutsideBlock) {
// Physical registers and those that are not live-out of the block are
// killed/dead at their last use/def within this block.
if (isPhysReg || !usedOutsideBlock || BBEndsInReturn)
if (MO.isUse()) {
// Don't mark uses that are tied to defs as kills.
if (!MI->isRegTiedToDefOperand(idx))
MO.setIsKill(true);
} else
} else {
MO.setIsDead(true);
}
}
}
}