[llvm] r298187 - NewGVN: Fix PHI evaluation bug exposed by new verifier. We were checking whether the incoming block was reachable instead of whether the specific edge was reachable

[Daniel Berlin via llvm-commits]

Author: dannyb
Date: Sat Mar 18 10:41:36 2017
New Revision: 298187

URL: http://llvm.org/viewvc/llvm-project?rev=298187&view=rev
Log:
NewGVN: Fix PHI evaluation bug exposed by new verifier. We were checking whether the incoming block was reachable instead of whether the specific edge was reachable

Added:
    llvm/trunk/test/Transforms/NewGVN/phi-edge-handling.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=298187&r1=298186&r2=298187&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp Sat Mar 18 10:41:36 2017
@@ -444,7 +444,7 @@ PHIExpression *NewGVN::createPHIExpressi
 
   // Filter out unreachable phi operands.
   auto Filtered = make_filter_range(PN->operands(), [&](const Use &U) {
-    return ReachableBlocks.count(PN->getIncomingBlock(U));
+    return ReachableEdges.count({PN->getIncomingBlock(U), PHIBlock});
   });
 
   std::transform(Filtered.begin(), Filtered.end(), op_inserter(E),
@@ -1740,10 +1740,11 @@ void NewGVN::valueNumberMemoryPhi(Memory
   // If all the arguments are the same, the MemoryPhi has the same value as the
   // argument.
   // Filter out unreachable blocks and self phis from our operands.
+  const BasicBlock *PHIBlock = MP->getBlock();
   auto Filtered = make_filter_range(MP->operands(), [&](const Use &U) {
     return lookupMemoryAccessEquiv(cast<MemoryAccess>(U)) != MP &&
            !isMemoryAccessTop(cast<MemoryAccess>(U)) &&
-           ReachableBlocks.count(MP->getIncomingBlock(U));
+           ReachableEdges.count({MP->getIncomingBlock(U), PHIBlock});
   });
   // If all that is left is nothing, our memoryphi is undef. We keep it as
   // InitialClass.  Note: The only case this should happen is if we have at
@@ -1822,7 +1823,7 @@ bool NewGVN::singleReachablePHIPath(cons
   } else {
     auto *MP = cast<MemoryPhi>(First);
     auto ReachableOperandPred = [&](const Use &U) {
-      return ReachableBlocks.count(MP->getIncomingBlock(U));
+      return ReachableEdges.count({MP->getIncomingBlock(U), MP->getBlock()});
     };
     auto FilteredPhiArgs =
         make_filter_range(MP->operands(), ReachableOperandPred);
@@ -1879,7 +1880,8 @@ void NewGVN::verifyMemoryCongruency() co
       // We can only sanely verify that MemoryDefs in the operand list all have
       // the same class.
       auto ReachableOperandPred = [&](const Use &U) {
-        return ReachableBlocks.count(FirstMP->getIncomingBlock(U)) &&
+        return ReachableEdges.count(
+                   {FirstMP->getIncomingBlock(U), FirstMP->getBlock()}) &&
                isa<MemoryDef>(U);
 
       };

Added: llvm/trunk/test/Transforms/NewGVN/phi-edge-handling.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/NewGVN/phi-edge-handling.ll?rev=298187&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/NewGVN/phi-edge-handling.ll (added)
+++ llvm/trunk/test/Transforms/NewGVN/phi-edge-handling.ll Sat Mar 18 10:41:36 2017
@@ -0,0 +1,60 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -newgvn -S | FileCheck %s
+
+
+;; Block 6 is reachable, but edge 6->4 is not
+;; This means the phi value is undef, not 0
+; Function Attrs: ssp uwtable
+define i16 @hoge() local_unnamed_addr #0 align 2 {
+; CHECK-LABEL: @hoge(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    switch i8 undef, label [[BB7:%.*]] [
+; CHECK-NEXT:    i8 0, label [[BB1:%.*]]
+; CHECK-NEXT:    i8 12, label [[BB2:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       bb1:
+; CHECK-NEXT:    br label [[BB6:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    br label [[BB4:%.*]]
+; CHECK:       bb3:
+; CHECK-NEXT:    unreachable
+; CHECK:       bb4:
+; CHECK-NEXT:    ret i16 undef
+; CHECK:       bb6:
+; CHECK-NEXT:    br i1 true, label [[BB3:%.*]], label [[BB4]], !llvm.loop !1
+; CHECK:       bb7:
+; CHECK-NEXT:    unreachable
+;
+bb:
+  switch i8 undef, label %bb7 [
+  i8 0, label %bb1
+  i8 12, label %bb2
+  ]
+
+bb1:                                              ; preds = %bb
+  br label %bb6
+
+bb2:                                              ; preds = %bb
+  br label %bb4
+
+bb3:                                              ; preds = %bb6
+  unreachable
+
+bb4:                                              ; preds = %bb6, %bb2
+  %tmp = phi i16 [ 0, %bb6 ], [ undef, %bb2 ]
+  ret i16 %tmp
+
+bb6:                                              ; preds = %bb4
+  br i1 true, label %bb3, label %bb4, !llvm.loop !1
+
+bb7:                                              ; preds = %bb
+  unreachable
+}
+
+attributes #0 = { ssp uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="penryn" "target-features"="+cx16,+fxsr,+mmx,+sse,+sse2,+sse3,+sse4.1,+ssse3,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.ident = !{!0}
+
+!0 = !{!"clang version 5.0.0 (http://llvm.org/git/clang.git a8b933d4d1d133594fdaed35ee5814514b738f6d) (/Users/dannyb/sources/llvm-clean fc630a9b5613f544c07a8f16abcc173793df62cf)"}
+!1 = distinct !{!1, !2}
+!2 = !{!"llvm.loop.unroll.disable"}