[llvm] r327834 - [SystemZ] Bugfix of CC liveness in emitMemMemWrapper (CLC).

[Jonas Paulsson via llvm-commits]

Author: jonpa
Date: Mon Mar 19 06:05:22 2018
New Revision: 327834

URL: http://llvm.org/viewvc/llvm-project?rev=327834&view=rev
Log:
[SystemZ]  Bugfix of CC liveness in emitMemMemWrapper (CLC).

If DoneMBB becomes empty it must have CC added to its live-in list, since it
will fall-through into EndMBB. This happens when the CLC loop does the
complete range.

Review: Ulrich Weigand

Added:
    llvm/trunk/test/CodeGen/SystemZ/memcmp-02.ll
Modified:
    llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp

Modified: llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp?rev=327834&r1=327833&r2=327834&view=diff
==============================================================================
--- llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp Mon Mar 19 06:05:22 2018
@@ -6626,6 +6626,10 @@ MachineBasicBlock *SystemZTargetLowering
     DestBase = MachineOperand::CreateReg(NextDestReg, false);
     SrcBase = MachineOperand::CreateReg(NextSrcReg, false);
     Length &= 255;
+    if (EndMBB && !Length)
+      // If the loop handled the whole CLC range, DoneMBB will be empty with
+      // CC live-through into EndMBB, so add it as live-in.
+      DoneMBB->addLiveIn(SystemZ::CC);
     MBB = DoneMBB;
   }
   // Handle any remaining bytes with straight-line code.

Added: llvm/trunk/test/CodeGen/SystemZ/memcmp-02.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/SystemZ/memcmp-02.ll?rev=327834&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/SystemZ/memcmp-02.ll (added)
+++ llvm/trunk/test/CodeGen/SystemZ/memcmp-02.ll Mon Mar 19 06:05:22 2018
@@ -0,0 +1,20 @@
+; Test memcmp using CLC.  In this test case the CLC loop will do all the work
+; and the DoneMBB becomes empty. It will not pass the mischeduling verifiers
+; if DoneMBB does not have CC in its live-in list.
+
+; RUN: llc < %s -mtriple=s390x-linux-gnu -misched=shuffle | FileCheck %s
+
+declare i32 @memcmp(i8* nocapture, i8* nocapture, i64)
+
+define i32 @fun() {
+; CHECK-LABEL: fun
+  %call = call signext i32 @memcmp(i8* nonnull undef, i8* nonnull undef, i64 2048)
+  %cmp = icmp eq i32 %call, 0
+  br i1 %cmp, label %labT, label %labF
+
+labT:
+  ret i32 0
+
+labF:
+  ret i32 1
+}