VirtRegMap: No implicit defs/uses for super registers with subreg liveness tracking.
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.
llvm-svn: 223892
diff --git a/llvm/lib/CodeGen/VirtRegMap.cpp b/llvm/lib/CodeGen/VirtRegMap.cpp
index 0d17d43..3d72d20 100644
--- a/llvm/lib/CodeGen/VirtRegMap.cpp
+++ b/llvm/lib/CodeGen/VirtRegMap.cpp
@@ -266,6 +266,7 @@
}
void VirtRegRewriter::rewrite() {
+ bool NoSubRegLiveness = !MRI->tracksSubRegLiveness();
SmallVector<unsigned, 8> SuperDeads;
SmallVector<unsigned, 8> SuperDefs;
SmallVector<unsigned, 8> SuperKills;
@@ -347,7 +348,8 @@
// 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 @@
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.