From: Chris Lattner <sabre@nondot.org>
Date: Wed, 18 Aug 2010 03:14:36 +0000 (+0000)
Subject: Fix PR7755: knowing something about an inval for a pred
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=2fa7b48eb594db245dc6af6060c92bbd2b19546b;p=oota-llvm.git

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 c2caf48b761..b17f80d39c0 100644
--- 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 4fe94e5ea0c..cfd90424312 100644
--- 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
+}