[AArch64][FastISel] Fix the setting of kill flags for MUL -> UMULH sequences.

rdar://problem/20748715

llvm-svn: 236346

1 files changed, 8 insertions, 2 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64FastISel.cpp b/llvm/lib/Target/AArch64/AArch64FastISel.cpp
index 837a31f303f..c70b17c8a32 100644
--- a/llvm/lib/Target/AArch64/AArch64FastISel.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FastISel.cpp
@@ -3598,7 +3598,10 @@ bool AArch64FastISel::fastLowerIntrinsicCall(const IntrinsicInst *II) {
                     AArch64_AM::ASR, 31, /*WantResult=*/false);
       } else {
         assert(VT == MVT::i64 && "Unexpected value type.");
-        MulReg = emitMul_rr(VT, LHSReg, LHSIsKill, RHSReg, RHSIsKill);
+        // LHSReg and RHSReg cannot be killed by this Mul, since they are
+        // reused in the next instruction.
+        MulReg = emitMul_rr(VT, LHSReg, /*IsKill=*/false, RHSReg,
+                            /*IsKill=*/false);
         unsigned SMULHReg = fastEmit_rr(VT, VT, ISD::MULHS, LHSReg, LHSIsKill,
                                         RHSReg, RHSIsKill);
         emitSubs_rs(VT, SMULHReg, /*IsKill=*/true, MulReg, /*IsKill=*/false,
@@ -3627,7 +3630,10 @@ bool AArch64FastISel::fastLowerIntrinsicCall(const IntrinsicInst *II) {
                                             AArch64::sub_32);
       } else {
         assert(VT == MVT::i64 && "Unexpected value type.");
-        MulReg = emitMul_rr(VT, LHSReg, LHSIsKill, RHSReg, RHSIsKill);
+        // LHSReg and RHSReg cannot be killed by this Mul, since they are
+        // reused in the next instruction.
+        MulReg = emitMul_rr(VT, LHSReg, /*IsKill=*/false, RHSReg,
+                            /*IsKill=*/false);
         unsigned UMULHReg = fastEmit_rr(VT, VT, ISD::MULHU, LHSReg, LHSIsKill,
                                         RHSReg, RHSIsKill);
         emitSubs_rr(VT, AArch64::XZR, /*IsKill=*/true, UMULHReg,