From c5cae0f20c946f1842544c7ffbf24659b3c81afc Mon Sep 17 00:00:00 2001
From: Amara Emerson <amara.emerson@arm.com>
Date: Thu, 24 Oct 2013 08:28:24 +0000
Subject: [PATCH] [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.

llvm-svn: 193316
---
 llvm/lib/Target/AArch64/AArch64ISelLowering.cpp |  8 ++++++--
 .../CodeGen/AArch64/regress-fp128-livein.ll     | 17 +++++++++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 llvm/test/CodeGen/AArch64/regress-fp128-livein.ll

diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index 40ed8af55172..c6b1d7a54124 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/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)
diff --git a/llvm/test/CodeGen/AArch64/regress-fp128-livein.ll b/llvm/test/CodeGen/AArch64/regress-fp128-livein.ll
new file mode 100644
index 000000000000..cb8432a7e4e4
--- /dev/null
+++ b/llvm/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)