Fix PR7755: knowing something about an inval for a pred

from the LHS should disable reconsidering that pred on the
RHS.  However, knowing something about the pred on the RHS
shouldn't disable subsequent additions on the RHS from
happening.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111349 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index c2caf48b76169ab455aeb23c274d40340257ad35..b17f80d39c0f6f6f36f8ebe09657c979d8d88495 100644 (file)
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -341,25 +341,21 @@ ComputeValueKnownInPredecessors(Value *V, BasicBlock *BB,PredValueInfo &Result){
       else
         InterestingVal = ConstantInt::getFalse(I->getContext());
       
+      SmallPtrSet<BasicBlock*, 4> LHSKnownBBs;
+      
       // Scan for the sentinel.  If we find an undef, force it to the
       // interesting value: x|undef -> true and x&undef -> false.
       for (unsigned i = 0, e = LHSVals.size(); i != e; ++i)
         if (LHSVals[i].first == InterestingVal || LHSVals[i].first == 0) {
           Result.push_back(LHSVals[i]);
           Result.back().first = InterestingVal;
+          LHSKnownBBs.insert(LHSVals[i].second);
         }
       for (unsigned i = 0, e = RHSVals.size(); i != e; ++i)
         if (RHSVals[i].first == InterestingVal || RHSVals[i].first == 0) {
           // 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) {
+          if (!LHSKnownBBs.count(RHSVals[i].second)) {
             Result.push_back(RHSVals[i]);
             Result.back().first = InterestingVal;
           }

diff --git a/test/Transforms/JumpThreading/crash.ll b/test/Transforms/JumpThreading/crash.ll
index 4fe94e5ea0c68dba2199ca66cb797387f5615229..cfd9042431250de58d844f3a738701510fb00cbf 100644 (file)
--- a/test/Transforms/JumpThreading/crash.ll
+++ b/test/Transforms/JumpThreading/crash.ll
@@ -436,4 +436,28 @@ for.cond1040:                                     ; preds = %for.body1044, %for.
   ret void
 }
 
+; PR7755
+define void @test16(i1 %c, i1 %c2, i1 %c3, i1 %c4) nounwind ssp {
+entry:
+  %cmp = icmp sgt i32 undef, 1                    ; <i1> [#uses=1]
+  br i1 %c, label %land.end, label %land.rhs
+
+land.rhs:                                         ; preds = %entry
+  br i1 %c2, label %lor.lhs.false.i, label %land.end
+
+lor.lhs.false.i:                                  ; preds = %land.rhs
+  br i1 %c3, label %land.end, label %land.end
+
+land.end:                            
+  %0 = phi i1 [ true, %entry ], [ false, %land.rhs ], [false, %lor.lhs.false.i], [false, %lor.lhs.false.i] ; <i1> [#uses=1]
+  %cmp12 = and i1 %cmp, %0 
+  %xor1 = xor i1 %cmp12, %c4
+  br i1 %xor1, label %if.then, label %if.end
+
+if.then:                      
+  ret void
+
+if.end:                       
+  ret void
+}