[AArch64] Fix NZCV reg live-in bug in F128CSEL codegen.

When generating the IfTrue basic block during the F128CSEL pseudo-instruction
handling, the NZCV live-in for the newly created BB wasn't being added. This
caused a fault during MI-sched/live range calculation when the predecessor
for the fall-through BB didn't have a live-in for phys-reg as expected.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193316 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/AArch64/AArch64ISelLowering.cpp

@@ -699,6 +699,12 @@ AArch64TargetLowering::EmitF128CSEL(MachineInstr *MI,
   MBB->addSuccessor(TrueBB);
   MBB->addSuccessor(EndBB);
 
+  if (!NZCVKilled) {
+    // NZCV is live-through TrueBB.
+    TrueBB->addLiveIn(AArch64::NZCV);
+    EndBB->addLiveIn(AArch64::NZCV);
+  }
+
   // IfTrue:
   //     str qIFTRUE, [sp]
   BuildMI(TrueBB, DL, TII->get(AArch64::LSFP128_STR))
@@ -713,8 +719,6 @@ AArch64TargetLowering::EmitF128CSEL(MachineInstr *MI,
   // Done:
   //     ldr qDEST, [sp]
   //     [... rest of incoming MBB ...]
-  if (!NZCVKilled)
-    EndBB->addLiveIn(AArch64::NZCV);
   MachineInstr *StartOfEnd = EndBB->begin();
   BuildMI(*EndBB, StartOfEnd, DL, TII->get(AArch64::LSFP128_LDR), DestReg)
     .addFrameIndex(ScratchFI)

test/CodeGen/AArch64/regress-fp128-livein.ll

@@ -0,0 +1,17 @@
+; RUN: llc -mtriple=aarch64-none-linux-gnu -verify-machineinstrs < %s
+
+; Regression test for NZCV reg live-in not being added to fp128csel IfTrue BB,
+; causing a crash during live range calc.
+define void @fp128_livein(i64 %a) {
+  %tobool = icmp ne i64 %a, 0
+  %conv = zext i1 %tobool to i32
+  %conv2 = sitofp i32 %conv to fp128
+  %conv6 = sitofp i32 %conv to double
+  %call3 = tail call i32 @g(fp128 %conv2)
+  %call8 = tail call i32 @h(double %conv6)
+  ret void
+}
+
+declare i32 @f()
+declare i32 @g(fp128)
+declare i32 @h(double)