[PATCH] D47531: [ValueTracking] Fix endless recursion in isKnownNonZero()

[Karl-Johan Karlsson via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL333557: [ValueTracking] Fix endless recursion in isKnownNonZero() (authored by karka, committed by ).

Changed prior to commit:
  https://reviews.llvm.org/D47531?vs=149114&id=149135#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D47531

Files:
  llvm/trunk/lib/Analysis/ValueTracking.cpp
  llvm/trunk/test/Transforms/CorrelatedValuePropagation/pointer.ll


Index: llvm/trunk/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp
@@ -1943,6 +1943,10 @@
     }
   }
 
+  // Some of the tests below are recursive, so bail out if we hit the limit.
+  if (Depth++ >= MaxDepth)
+    return false;
+
   // Check for pointer simplifications.
   if (V->getType()->isPointerTy()) {
     // Alloca never returns null, malloc might.
@@ -1963,13 +1967,10 @@
       if (CS.isReturnNonNull())
         return true;
       if (const auto *RP = getArgumentAliasingToReturnedPointer(CS))
-        return isKnownNonZero(RP, Depth + 1, Q);
+        return isKnownNonZero(RP, Depth, Q);
     }
   }
 
-  // The remaining tests are all recursive, so bail out if we hit the limit.
-  if (Depth++ >= MaxDepth)
-    return false;
 
   // Check for recursive pointer simplifications.
   if (V->getType()->isPointerTy()) {
Index: llvm/trunk/test/Transforms/CorrelatedValuePropagation/pointer.ll
===================================================================
--- llvm/trunk/test/Transforms/CorrelatedValuePropagation/pointer.ll
+++ llvm/trunk/test/Transforms/CorrelatedValuePropagation/pointer.ll
@@ -0,0 +1,35 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -correlated-propagation -S -o - %s | FileCheck %s
+
+; Testcase that checks that we don't end in a neverending recursion resulting in
+; a segmentation fault. The checks below verify that nothing is changed.
+
+declare dso_local i16* @f2(i16* readnone returned) local_unnamed_addr
+
+define dso_local void @f3() local_unnamed_addr {
+; CHECK-LABEL: @f3(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_COND:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    [[CALL6:%.*]] = call i16* @f2(i16* [[CALL6]])
+; CHECK-NEXT:    br i1 false, label [[FOR_COND]], label [[FOR_COND3:%.*]]
+; CHECK:       for.cond:
+; CHECK-NEXT:    [[C_0:%.*]] = phi i16* [ undef, [[ENTRY:%.*]] ], [ [[CALL6]], [[FOR_END:%.*]] ]
+; CHECK-NEXT:    br label [[FOR_COND3]]
+; CHECK:       for.cond3:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.cond
+
+for.end:
+  %call6 = call i16* @f2(i16* %call6)
+  br i1 false, label %for.cond, label %for.cond3
+
+for.cond:
+  %c.0 = phi i16* [ undef, %entry ], [ %call6, %for.end ]
+  br label %for.cond3
+
+for.cond3:
+  ret void
+}


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