[PPC64] Mark CR0 Live if PPCInstrInfo::optimizeCompareInstr Creates a Use of CR0
Resolve Bug 27046 (https://llvm.org/bugs/show_bug.cgi?id=27046).
The PPCInstrInfo::optimizeCompareInstr function could create a new use of
CR0, even if CR0 were previously dead. This patch marks CR0 live if a use of
CR0 is created.
Author: Tom Jablin (tjablin)
Reviewers: hfinkel kbarton cycheng
http://reviews.llvm.org/D18884
llvm-svn: 266040
diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
index 76f97b1..b6dc00f 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -1763,6 +1763,10 @@
get(TargetOpcode::COPY), CRReg)
.addReg(PPC::CR0, MIOpC != NewOpC ? RegState::Kill : 0);
+ // Even if CR0 register were dead before, it is alive now since the
+ // instruction we just built uses it.
+ MI->clearRegisterDeads(PPC::CR0);
+
if (MIOpC != NewOpC) {
// We need to be careful here: we're replacing one instruction with
// another, and we need to make sure that we get all of the right