Disable local spill hoisting for non-killing copies.
If the source register is live after the copy being spilled, there is no
point to hoisting it. Hoisting inside a basic block only serves to
resolve interferences by shortening the live range of the source.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139882 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/InlineSpiller.cpp b/lib/CodeGen/InlineSpiller.cpp
index 01fe840..b63611b 100644
--- a/lib/CodeGen/InlineSpiller.cpp
+++ b/lib/CodeGen/InlineSpiller.cpp
@@ -90,6 +90,9 @@
// True when value is defined by an original PHI not from splitting.
bool DefByOrigPHI;
+ // True when the COPY defining this value killed its source.
+ bool KillsSource;
+
// The preferred register to spill.
unsigned SpillReg;
@@ -112,7 +115,7 @@
TinyPtrVector<VNInfo*> Deps;
SibValueInfo(unsigned Reg, VNInfo *VNI)
- : AllDefsAreReloads(true), DefByOrigPHI(false),
+ : AllDefsAreReloads(true), DefByOrigPHI(false), KillsSource(false),
SpillReg(Reg), SpillVNI(VNI), SpillMBB(0), DefMI(0) {}
// Returns true when a def has been found.
@@ -319,6 +322,8 @@
OS << " all-reloads";
if (SVI.DefByOrigPHI)
OS << " orig-phi";
+ if (SVI.KillsSource)
+ OS << " kill";
OS << " deps[";
for (unsigned i = 0, e = SVI.Deps.size(); i != e; ++i)
OS << ' ' << SVI.Deps[i]->id << '@' << SVI.Deps[i]->def;
@@ -402,7 +407,7 @@
if (PropSpill && SV.SpillVNI != DepSV.SpillVNI) {
if (SV.SpillMBB == DepSV.SpillMBB) {
// DepSV is in the same block. Hoist when dominated.
- if (SV.SpillVNI->def < DepSV.SpillVNI->def) {
+ if (DepSV.KillsSource && SV.SpillVNI->def < DepSV.SpillVNI->def) {
// This is an alternative def earlier in the same MBB.
// Hoist the spill as far as possible in SpillMBB. This can ease
// register pressure:
@@ -418,6 +423,7 @@
// spill x
// y = use x<kill>
//
+ // This hoist only helps when the DepSV copy kills its source.
Changed = true;
DepSV.SpillReg = SV.SpillReg;
DepSV.SpillVNI = SV.SpillVNI;
@@ -572,10 +578,14 @@
if (unsigned SrcReg = isFullCopyOf(MI, Reg)) {
if (isSibling(SrcReg)) {
LiveInterval &SrcLI = LIS.getInterval(SrcReg);
- VNInfo *SrcVNI = SrcLI.getVNInfoAt(VNI->def.getUseIndex());
- assert(SrcVNI && "Copy from non-existing value");
+ LiveRange *SrcLR = SrcLI.getLiveRangeContaining(VNI->def.getUseIndex());
+ assert(SrcLR && "Copy from non-existing value");
+ // Check if this COPY kills its source.
+ SVI->second.KillsSource = (SrcLR->end == VNI->def);
+ VNInfo *SrcVNI = SrcLR->valno;
DEBUG(dbgs() << "copy of " << PrintReg(SrcReg) << ':'
- << SrcVNI->id << '@' << SrcVNI->def << '\n');
+ << SrcVNI->id << '@' << SrcVNI->def
+ << " kill=" << unsigned(SVI->second.KillsSource) << '\n');
// Known sibling source value? Try an insertion.
tie(SVI, Inserted) = SibValues.insert(std::make_pair(SrcVNI,
SibValueInfo(SrcReg, SrcVNI)));
