6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-06-12 13:38:21 +00:00
Code Issues Projects Releases Wiki Activity

Dead code elimination may separate the live interval into multiple connected components.

Browse Source 
I have convinced myself that it can only happen when a phi value dies. When it
happens, allocate new virtual registers for the components.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127827 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2011-03-17 20:37:07 +00:00
parent c74513d1b6
commit 6a3dbd3b25
6 changed files with 47 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
lib/CodeGen/LiveIntervalAnalysis.cpp
View File

@ -746,7 +746,7 @@ LiveInterval* LiveIntervals::dupInterval(LiveInterval *li) {
/// shrinkToUses - After removing some uses of a register, shrink its live
/// range to just the remaining uses. This method does not compute reaching
/// defs for new uses, and it doesn't remove dead defs.
void LiveIntervals::shrinkToUses(LiveInterval *li,
bool LiveIntervals::shrinkToUses(LiveInterval *li,
SmallVectorImpl<MachineInstr*> *dead) {
DEBUG(dbgs() << "Shrink: " << *li << '\n');
assert(TargetRegisterInfo::isVirtualRegister(li->reg)
@ -835,6 +835,7 @@ void LiveIntervals::shrinkToUses(LiveInterval *li,
}
// Handle dead values.
bool CanSeparate = false;
for (LiveInterval::vni_iterator I = li->vni_begin(), E = li->vni_end();
I != E; ++I) {
VNInfo *VNI = *I;
@ -848,6 +849,8 @@ void LiveIntervals::shrinkToUses(LiveInterval *li,
// This is a dead PHI. Remove it.
VNI->setIsUnused(true);
NewLI.removeRange(*LII);
DEBUG(dbgs() << "Dead PHI at " << VNI->def << " may separate interval\n");
CanSeparate = true;
} else {
// This is a dead def. Make sure the instruction knows.
MachineInstr *MI = getInstructionFromIndex(VNI->def);
@ -863,6 +866,7 @@ void LiveIntervals::shrinkToUses(LiveInterval *li,
// Move the trimmed ranges back.
li->ranges.swap(NewLI.ranges);
DEBUG(dbgs() << "Shrunk: " << *li << '\n');
return CanSeparate;
}