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Fix in InlineSpiller to make the rematerilization loop also consider

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implicit uses of the whole register when a sub register is defined.

Now the same iterator is used in the rematerilization loop as in the
spill loop later.

Patch provided by Mikael Holmen.

This fix was proposed and reviewed by Quentin Colombet,
http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-August/076135.html.

Unfortunately, this error in the rematerilization code has only been
seen in a large test case for an out-of-tree target, and is probably
hard to reproduce on an in-tree target. Therefore, no testcase is
provided.

llvm-svn: 216873
This commit is contained in:
Patrik Hagglund 2014-09-01 11:04:07 +00:00
parent 424ae489be
commit 58aa72df97
1 changed files with 18 additions and 7 deletions
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25
lib/CodeGen/InlineSpiller.cpp
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@ -848,6 +848,15 @@ void InlineSpiller::markValueUsed(LiveInterval *LI, VNInfo *VNI) {
/// reMaterializeFor - Attempt to rematerialize before MI instead of reloading.
bool InlineSpiller::reMaterializeFor(LiveInterval &VirtReg,
MachineBasicBlock::iterator MI) {
// Analyze instruction
SmallVector<std::pair<MachineInstr *, unsigned>, 8> Ops;
MIBundleOperands::VirtRegInfo RI =
MIBundleOperands(MI).analyzeVirtReg(VirtReg.reg, &Ops);
if (!RI.Reads)
return false;
SlotIndex UseIdx = LIS.getInstructionIndex(MI).getRegSlot(true);
VNInfo *ParentVNI = VirtReg.getVNInfoAt(UseIdx.getBaseIndex());
@ -878,9 +887,6 @@ bool InlineSpiller::reMaterializeFor(LiveInterval &VirtReg,
// If the instruction also writes VirtReg.reg, it had better not require the
// same register for uses and defs.
SmallVector<std::pair<MachineInstr*, unsigned>, 8> Ops;
MIBundleOperands::VirtRegInfo RI =
MIBundleOperands(MI).analyzeVirtReg(VirtReg.reg, &Ops);
if (RI.Tied) {
markValueUsed(&VirtReg, ParentVNI);
DEBUG(dbgs() << "\tcannot remat tied reg: " << UseIdx << '\t' << *MI);
@ -934,10 +940,15 @@ void InlineSpiller::reMaterializeAll() {
for (unsigned i = 0, e = RegsToSpill.size(); i != e; ++i) {
unsigned Reg = RegsToSpill[i];
LiveInterval &LI = LIS.getInterval(Reg);
for (MachineRegisterInfo::use_bundle_nodbg_iterator
RI = MRI.use_bundle_nodbg_begin(Reg), E = MRI.use_bundle_nodbg_end();
RI != E; ) {
MachineInstr *MI = &*(RI++);
for (MachineRegisterInfo::reg_bundle_iterator
RegI = MRI.reg_bundle_begin(Reg), E = MRI.reg_bundle_end();
RegI != E; ) {
MachineInstr *MI = &*(RegI++);
// Debug values are not allowed to affect codegen.
if (MI->isDebugValue())
continue;
anyRemat |= reMaterializeFor(LI, MI);
}
}