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More handling of DBG_VALUE.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96294 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen 2010-02-15 23:05:03 +00:00
parent 04c60d9535
commit a95f9ed2b8
1 changed files with 26 additions and 4 deletions
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28
lib/CodeGen/RegAllocLocal.cpp
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@ -490,10 +490,12 @@ MachineInstr *RALocal::reloadVirtReg(MachineBasicBlock &MBB, MachineInstr *MI,
// If the virtual register is already available, just update the instruction
// and return.
if (unsigned PR = getVirt2PhysRegMapSlot(VirtReg)) {
MarkPhysRegRecentlyUsed(PR); // Already have this value available!
MI->getOperand(OpNum).setReg(PR); // Assign the input register
if (!MI->isDebugValue())
if (!MI->isDebugValue()) {
// Do not do these for DBG_VALUE as they can affect codegen.
MarkPhysRegRecentlyUsed(PR); // Already have this value available!
getVirtRegLastUse(VirtReg) = std::make_pair(MI, OpNum);
}
return MI;
}
@ -694,7 +696,13 @@ void RALocal::ComputeLocalLiveness(MachineBasicBlock& MBB) {
bool usedOutsideBlock = isPhysReg ? false :
UsedInMultipleBlocks.test(MO.getReg() -
TargetRegisterInfo::FirstVirtualRegister);
if (!isPhysReg && !usedOutsideBlock)
if (!isPhysReg && !usedOutsideBlock) {
// 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
// it wouldn't have been otherwise. Nullify the DBG_VALUEs when that
// happens.
bool UsedByDebugValueOnly = false;
for (MachineRegisterInfo::reg_iterator UI = MRI.reg_begin(MO.getReg()),
UE = MRI.reg_end(); UI != UE; ++UI)
// Two cases:
@ -702,11 +710,25 @@ void RALocal::ComputeLocalLiveness(MachineBasicBlock& MBB) {
// - used in the same block before it is defined (loop)
if (UI->getParent() != &MBB ||
(MO.isDef() && UI.getOperand().isUse() && precedes(&*UI, MI))) {
if (UI->isDebugValue()) {
UsedByDebugValueOnly = true;
continue;
}
// A non-DBG_VALUE use means we can leave DBG_VALUE uses alone.
UsedInMultipleBlocks.set(MO.getReg() -
TargetRegisterInfo::FirstVirtualRegister);
usedOutsideBlock = true;
UsedByDebugValueOnly = false;
break;
}
if (UsedByDebugValueOnly)
for (MachineRegisterInfo::reg_iterator UI = MRI.reg_begin(MO.getReg()),
UE = MRI.reg_end(); UI != UE; ++UI)
if (UI->isDebugValue() &&
(UI->getParent() != &MBB ||
(MO.isDef() && precedes(&*UI, MI))))
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.