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VirtRegMap: No implicit defs/uses for super registers with subreg liveness tracking.

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Adding the implicit defs/uses to the superregisters is semantically questionable
but was not dangerous before as the register allocator never assigned the same
register to two overlapping LiveIntervals even when the actually live
subregisters do not overlap. With subregister liveness tracking enabled this
does actually happen and leads to subsequent bugs if we don't stop adding
the superregister defs/uses.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223892 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Matthias Braun
2014-12-10 01:13:04 +00:00
parent 0fc28990e4
commit 668132490c
2 changed files with 33 additions and 5 deletions
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14
lib/CodeGen/VirtRegMap.cpp
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@@ -266,6 +266,7 @@ void VirtRegRewriter::addMBBLiveIns() {
}
void VirtRegRewriter::rewrite() {
bool NoSubRegLiveness = !MRI->tracksSubRegLiveness();
SmallVector<unsigned, 8> SuperDeads;
SmallVector<unsigned, 8> SuperDefs;
SmallVector<unsigned, 8> SuperKills;
@@ -347,7 +348,8 @@ void VirtRegRewriter::rewrite() {
// A virtual register kill refers to the whole register, so we may
// have to add <imp-use,kill> operands for the super-register. A
// partial redef always kills and redefines the super-register.
if (MO.readsReg() && (MO.isDef() || MO.isKill()))
if (NoSubRegLiveness && MO.readsReg()
&& (MO.isDef() || MO.isKill()))
SuperKills.push_back(PhysReg);
if (MO.isDef()) {
@@ -358,10 +360,12 @@ void VirtRegRewriter::rewrite() {
MO.setIsUndef(false);
// Also add implicit defs for the super-register.
if (MO.isDead())
SuperDeads.push_back(PhysReg);
else
SuperDefs.push_back(PhysReg);
if (NoSubRegLiveness) {
if (MO.isDead())
SuperDeads.push_back(PhysReg);
else
SuperDefs.push_back(PhysReg);
}
}
// PhysReg operands cannot have subregister indexes.