[llvm] r319674 - MachineVerifier: undef phi arg doesn't need to be live-out from predecessor

[Matthias Braun via llvm-commits]

Author: matze
Date: Mon Dec  4 10:57:48 2017
New Revision: 319674

URL: http://llvm.org/viewvc/llvm-project?rev=319674&view=rev
Log:
MachineVerifier: undef phi arg doesn't need to be live-out from predecessor

Differential Revision: https://reviews.llvm.org/D40756

Added:
    llvm/trunk/test/CodeGen/X86/verifier-phi-fail0.mir
    llvm/trunk/test/CodeGen/X86/verifier-phi.mir
Modified:
    llvm/trunk/lib/CodeGen/MachineVerifier.cpp

Modified: llvm/trunk/lib/CodeGen/MachineVerifier.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineVerifier.cpp?rev=319674&r1=319673&r2=319674&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineVerifier.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineVerifier.cpp Mon Dec  4 10:57:48 2017
@@ -1652,7 +1652,8 @@ void MachineVerifier::checkPHIOps(const
       if (MInfo.reachable) {
         seen.insert(&Pre);
         BBInfo &PrInfo = MBBInfoMap[&Pre];
-        if (PrInfo.reachable && !PrInfo.isLiveOut(MO0.getReg()))
+        if (!MO0.isUndef() && PrInfo.reachable &&
+            !PrInfo.isLiveOut(MO0.getReg()))
           report("PHI operand is not live-out from predecessor", &MO0, I);
       }
     }

Added: llvm/trunk/test/CodeGen/X86/verifier-phi-fail0.mir
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/verifier-phi-fail0.mir?rev=319674&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/verifier-phi-fail0.mir (added)
+++ llvm/trunk/test/CodeGen/X86/verifier-phi-fail0.mir Mon Dec  4 10:57:48 2017
@@ -0,0 +1,30 @@
+# RUN: not llc -o - %s -verify-machineinstrs -run-pass=none 2>&1 | FileCheck %s
+---
+# CHECK: Bad machine code: PHI operand is not live-out from predecessor
+# CHECK: - function:    func0
+# CHECK: - basic block: %bb.3
+# CHECK: - instruction: %0<def> = PHI
+# CHECK: - operand 1:   %1
+#
+# CHECK: Bad machine code: PHI operand is not live-out from predecessor
+# CHECK: - function:    func0
+# CHECK: - basic block: %bb.3
+# CHECK: - instruction: %0<def> = PHI
+# CHECK: - operand 3:   %0
+name: func0
+tracksRegLiveness: true
+body: |
+  bb.0:
+    JE_1 %bb.1, implicit undef %eflags
+    JMP_1 %bb.2
+
+  bb.1:
+    %0:gr32 = IMPLICIT_DEF
+    JMP_1 %bb.3
+
+  bb.2:
+    %1:gr32 = IMPLICIT_DEF
+
+  bb.3:
+    %0:gr32 = PHI %1, %bb.1, %0, %bb.2
+...

Added: llvm/trunk/test/CodeGen/X86/verifier-phi.mir
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/verifier-phi.mir?rev=319674&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/verifier-phi.mir (added)
+++ llvm/trunk/test/CodeGen/X86/verifier-phi.mir Mon Dec  4 10:57:48 2017
@@ -0,0 +1,34 @@
+# RUN: llc -o - %s -verify-machineinstrs -run-pass=none | FileCheck %s
+# This should cleanly pass the machine verifier
+---
+# CHECK-LABEL: name: func0
+# CHECK: %0:gr32 = PHI undef %1:gr32, %bb.0, undef %1:gr32, %bb.1
+name: func0
+tracksRegLiveness: true
+body: |
+  bb.0:
+    JE_1 %bb.1, implicit undef %eflags
+    JMP_1 %bb.2
+
+  bb.1:
+
+  bb.2:
+    %0 : gr32 = PHI undef %1 : gr32, %bb.0, undef %1 : gr32, %bb.1
+...
+---
+# CHECK-LABEL: name: func1
+# CHECK: %2:gr32 = PHI %0, %bb.0, %1, %bb.1
+name: func1
+tracksRegLiveness: true
+body: |
+  bb.0:
+    %0 : gr32 = IMPLICIT_DEF
+    JE_1 %bb.1, implicit undef %eflags
+    JMP_1 %bb.2
+
+  bb.1:
+    %1 : gr32 = IMPLICIT_DEF
+
+  bb.2:
+    %2 : gr32 = PHI %0, %bb.0, %1, %bb.1
+...