[PowerPC] Sign extend sub-word values for atomic comparisons
Atomic comparison instructions use the sub-word load instruction on
Power8 and up but the value is not sign extended prior to the signed word
compare instruction. This patch adds that sign extension.
llvm-svn: 282182
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 1d9181b..c414a15 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -8507,8 +8507,17 @@
if (BinOpcode)
BuildMI(BB, dl, TII->get(BinOpcode), TmpReg).addReg(incr).addReg(dest);
if (CmpOpcode) {
- BuildMI(BB, dl, TII->get(CmpOpcode), PPC::CR0)
- .addReg(incr).addReg(dest);
+ // Signed comparisons of byte or halfword values must be sign-extended.
+ if (CmpOpcode == PPC::CMPW && AtomicSize < 4) {
+ unsigned ExtReg = RegInfo.createVirtualRegister(&PPC::GPRCRegClass);
+ BuildMI(BB, dl, TII->get(AtomicSize == 1 ? PPC::EXTSB : PPC::EXTSH),
+ ExtReg).addReg(dest);
+ BuildMI(BB, dl, TII->get(CmpOpcode), PPC::CR0)
+ .addReg(incr).addReg(ExtReg);
+ } else
+ BuildMI(BB, dl, TII->get(CmpOpcode), PPC::CR0)
+ .addReg(incr).addReg(dest);
+
BuildMI(BB, dl, TII->get(PPC::BCC))
.addImm(CmpPred).addReg(PPC::CR0).addMBB(exitMBB);
BB->addSuccessor(loop2MBB);