[AMDGPU] Prevent Machine Copy Propagation from replacing live copy with the dead one
Differential revision: https://reviews.llvm.org/D38754
llvm-svn: 315908
diff --git a/llvm/lib/CodeGen/MachineCopyPropagation.cpp b/llvm/lib/CodeGen/MachineCopyPropagation.cpp
index 4655b5b..030db43 100644
--- a/llvm/lib/CodeGen/MachineCopyPropagation.cpp
+++ b/llvm/lib/CodeGen/MachineCopyPropagation.cpp
@@ -275,18 +275,20 @@
ClobberRegister(Reg);
}
- // Remember Def is defined by the copy.
- for (MCSubRegIterator SR(Def, TRI, /*IncludeSelf=*/true); SR.isValid();
- ++SR) {
- CopyMap[*SR] = MI;
- AvailCopyMap[*SR] = MI;
- }
+ if (!MI->getOperand(0).isDead() && !MI->getOperand(1).isUndef()) {
+ // Remember Def is defined by the copy.
+ for (MCSubRegIterator SR(Def, TRI, /*IncludeSelf=*/true); SR.isValid();
+ ++SR) {
+ CopyMap[*SR] = MI;
+ AvailCopyMap[*SR] = MI;
+ }
- // Remember source that's copied to Def. Once it's clobbered, then
- // it's no longer available for copy propagation.
- RegList &DestList = SrcMap[Src];
- if (!is_contained(DestList, Def))
- DestList.push_back(Def);
+ // Remember source that's copied to Def. Once it's clobbered, then
+ // it's no longer available for copy propagation.
+ RegList &DestList = SrcMap[Src];
+ if (!is_contained(DestList, Def))
+ DestList.push_back(Def);
+ }
continue;
}