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Use readsWritesVirtualRegister instead of counting uses and defs when inserting

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spills and reloads.

This means that a partial define of a register causes a reload so the other
parts of the register are preserved.

The reload can be prevented by adding an <imp-def> operand for the full
register. This is already done by the coalescer and live interval analysis where
relevant.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105369 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2010-06-03 00:07:47 +00:00
parent 02571a3a1f
commit ead06be02f
1 changed files with 8 additions and 46 deletions
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54
lib/CodeGen/LiveIntervalAnalysis.cpp
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@ -1098,7 +1098,6 @@ rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
if (!mop.isReg())
continue;
unsigned Reg = mop.getReg();
unsigned RegI = Reg;
if (Reg == 0 || TargetRegisterInfo::isPhysicalRegister(Reg))
continue;
if (Reg != li.reg)
@ -1140,26 +1139,8 @@ rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
//
// Keep track of whether we replace a use and/or def so that we can
// create the spill interval with the appropriate range.
HasUse = mop.isUse();
HasDef = mop.isDef();
SmallVector<unsigned, 2> Ops;
Ops.push_back(i);
for (unsigned j = i+1, e = MI->getNumOperands(); j != e; ++j) {
const MachineOperand &MOj = MI->getOperand(j);
if (!MOj.isReg())
continue;
unsigned RegJ = MOj.getReg();
if (RegJ == 0 || TargetRegisterInfo::isPhysicalRegister(RegJ))
continue;
if (RegJ == RegI) {
Ops.push_back(j);
if (!MOj.isUndef()) {
HasUse |= MOj.isUse();
HasDef |= MOj.isDef();
}
}
}
tie(HasUse, HasDef) = MI->readsWritesVirtualRegister(Reg, &Ops);
// Create a new virtual register for the spill interval.
// Create the new register now so we can map the fold instruction
@ -1312,10 +1293,7 @@ namespace {
struct RewriteInfo {
SlotIndex Index;
MachineInstr *MI;
bool HasUse;
bool HasDef;
RewriteInfo(SlotIndex i, MachineInstr *mi, bool u, bool d)
: Index(i), MI(mi), HasUse(u), HasDef(d) {}
RewriteInfo(SlotIndex i, MachineInstr *mi) : Index(i), MI(mi) {}
};
struct RewriteInfoCompare {
@ -1394,7 +1372,7 @@ rewriteInstructionsForSpills(const LiveInterval &li, bool TrySplit,
// easily see a situation where both registers are reloaded before
// the INSERT_SUBREG and both target registers that would overlap.
continue;
RewriteMIs.push_back(RewriteInfo(index, MI, O.isUse(), O.isDef()));
RewriteMIs.push_back(RewriteInfo(index, MI));
}
std::sort(RewriteMIs.begin(), RewriteMIs.end(), RewriteInfoCompare());
@ -1404,18 +1382,11 @@ rewriteInstructionsForSpills(const LiveInterval &li, bool TrySplit,
RewriteInfo &rwi = RewriteMIs[i];
++i;
SlotIndex index = rwi.Index;
bool MIHasUse = rwi.HasUse;
bool MIHasDef = rwi.HasDef;
MachineInstr *MI = rwi.MI;
// If MI def and/or use the same register multiple times, then there
// are multiple entries.
unsigned NumUses = MIHasUse;
while (i != e && RewriteMIs[i].MI == MI) {
assert(RewriteMIs[i].Index == index);
bool isUse = RewriteMIs[i].HasUse;
if (isUse) ++NumUses;
MIHasUse |= isUse;
MIHasDef |= RewriteMIs[i].HasDef;
++i;
}
MachineBasicBlock *MBB = MI->getParent();
@ -1440,7 +1411,8 @@ rewriteInstructionsForSpills(const LiveInterval &li, bool TrySplit,
// = use
// It's better to start a new interval to avoid artifically
// extend the new interval.
if (MIHasDef && !MIHasUse) {
if (MI->readsWritesVirtualRegister(li.reg) ==
std::make_pair(false,true)) {
MBBVRegsMap.erase(MBB->getNumber());
ThisVReg = 0;
}
@ -1674,19 +1646,9 @@ addIntervalsForSpillsFast(const LiveInterval &li,
MachineInstr* MI = &*RI;
SmallVector<unsigned, 2> Indices;
bool HasUse = false;
bool HasDef = false;
for (unsigned i = 0; i != MI->getNumOperands(); ++i) {
MachineOperand& mop = MI->getOperand(i);
if (!mop.isReg() || mop.getReg() != li.reg) continue;
HasUse |= MI->getOperand(i).isUse();
HasDef |= MI->getOperand(i).isDef();
Indices.push_back(i);
}
bool HasUse, HasDef;
tie(HasUse, HasDef) = MI->readsWritesVirtualRegister(li.reg, &Indices);
if (!tryFoldMemoryOperand(MI, vrm, NULL, getInstructionIndex(MI),
Indices, true, slot, li.reg)) {
unsigned NewVReg = mri_->createVirtualRegister(rc);