if jump threading is able to infer interesting values on both

the LHS and RHS of an and/or instruction, don't multiply add
known predecessor values.  This fixes the crash on testcase
from PR7498

llvm-svn: 108114

2 files changed, 37 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index 1a64b2cbad7..f68011a08ad 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -346,8 +346,19 @@ ComputeValueKnownInPredecessors(Value *V, BasicBlock *BB,PredValueInfo &Result){
         }
       for (unsigned i = 0, e = RHSVals.size(); i != e; ++i)
         if (RHSVals[i].first == InterestingVal || RHSVals[i].first == 0) {
-          Result.push_back(RHSVals[i]);
-          Result.back().first = InterestingVal;
+          // If we already inferred a value for this block on the LHS, don't
+          // re-add it.
+          bool HasValue = false;
+          for (unsigned r = 0, e = Result.size(); r != e; ++r)
+            if (Result[r].second == RHSVals[i].second) {
+              HasValue = true;
+              break;
+            }
+          
+          if (!HasValue) {
+            Result.push_back(RHSVals[i]);
+            Result.back().first = InterestingVal;
+          }
         }
       return !Result.empty();
     }
diff --git a/llvm/test/Transforms/JumpThreading/crash.ll b/llvm/test/Transforms/JumpThreading/crash.ll
index 378c51a44a7..480b4a04ee9 100644
--- a/llvm/test/Transforms/JumpThreading/crash.ll
+++ b/llvm/test/Transforms/JumpThreading/crash.ll
@@ -363,3 +363,27 @@ F:
   ret i32 1422
 }
 
+
+; PR7498
+define void @test14() nounwind {
+entry:
+  %cmp33 = icmp slt i8 undef, 0                   ; <i1> [#uses=1]
+  %tobool = icmp eq i8 undef, 0                   ; <i1> [#uses=1]
+  br i1 %tobool, label %land.end69, label %land.rhs
+
+land.rhs:                                         ; preds = %entry
+  br label %land.end69
+
+land.end69:                                       ; preds = %land.rhs, %entry
+  %0 = phi i1 [ undef, %land.rhs ], [ true, %entry ] ; <i1> [#uses=1]
+  %cmp71 = or i1 true, %0                         ; <i1> [#uses=1]
+  %cmp73 = xor i1 %cmp33, %cmp71                  ; <i1> [#uses=1]
+  br i1 %cmp73, label %if.then, label %if.end
+
+if.then:                                          ; preds = %land.end69
+  ret void
+
+if.end:                                           ; preds = %land.end69
+  ret void
+}
+