[llvm] r303100 - [NewGVN] Fix verification of MemoryPhis in verifyMemoryCongruency().

[Davide Italiano via llvm-commits]

Author: davide
Date: Mon May 15 13:50:53 2017
New Revision: 303100

URL: http://llvm.org/viewvc/llvm-project?rev=303100&view=rev
Log:
[NewGVN] Fix verification of MemoryPhis in verifyMemoryCongruency().

verifyMemoryCongruency() filters out trivially dead MemoryDef(s),
as we find them immediately dead, before moving from TOP to a new
congruence class.
This fixes the same problem for PHI(s) skipping MemoryPhis if all
the operands are dead.

Differential Revision:  https://reviews.llvm.org/D33044

Added:
    llvm/trunk/test/Transforms/NewGVN/verify-memoryphi.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp?rev=303100&r1=303099&r2=303100&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp Mon May 15 13:50:53 2017
@@ -2549,6 +2549,19 @@ void NewGVN::verifyMemoryCongruency() co
           return false;
         if (auto *MemDef = dyn_cast<MemoryDef>(Pair.first))
           return !isInstructionTriviallyDead(MemDef->getMemoryInst());
+
+        // We could have phi nodes which operands are all trivially dead,
+        // so we don't process them.
+        if (auto *MemPHI = dyn_cast<MemoryPhi>(Pair.first)) {
+          for (auto &U : MemPHI->incoming_values()) {
+            if (Instruction *I = dyn_cast<Instruction>(U.get())) {
+              if (!isInstructionTriviallyDead(I))
+                return true;
+            }
+          }
+          return false;
+        }
+
         return true;
       };
 

Added: llvm/trunk/test/Transforms/NewGVN/verify-memoryphi.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/NewGVN/verify-memoryphi.ll?rev=303100&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/NewGVN/verify-memoryphi.ll (added)
+++ llvm/trunk/test/Transforms/NewGVN/verify-memoryphi.ll Mon May 15 13:50:53 2017
@@ -0,0 +1,29 @@
+; Skip dead MemoryPhis when performing memory congruency verification
+; in NewGVN.
+; RUN: opt -S -newgvn %s | FileCheck %s
+; REQUIRES: asserts
+
+; CHECK: define void @tinkywinky() {
+; CHECK-NEXT: entry:
+; CHECK-NEXT:   br i1 false, label %body, label %end
+; CHECK:      body:
+; CHECK-NEXT:   store i8 undef, i8* null
+; CHECK-NEXT:   br label %end
+; CHECK:      end:
+; CHECK-NEXT:   ret void
+; CHECK-NEXT: }
+
+declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture)
+
+define void @tinkywinky() {
+entry:
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* undef)
+  br i1 false, label %body, label %end
+
+body:
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* undef)
+  br label %end
+
+end:
+  ret void
+}