[llvm-commits] [llvm] r95852 - in /llvm/trunk: lib/Transforms/Scalar/DeadStoreElimination.cpp test/Transforms/DeadStoreElimination/crash.ll

[Chris Lattner]

Author: lattner
Date: Wed Feb 10 23:11:54 2010
New Revision: 95852

URL: http://llvm.org/viewvc/llvm-project?rev=95852&view=rev
Log:
Make DSE only scan blocks that are reachable from the entry
block.  Other blocks may have pointer cycles that will crash
basicaa and other alias analyses.  In any case, there is no
point wasting cycles optimizing dead blocks.  This fixes 
rdar://7635088

Modified:
    llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp
    llvm/trunk/test/Transforms/DeadStoreElimination/crash.ll

Modified: llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp?rev=95852&r1=95851&r2=95852&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp Wed Feb 10 23:11:54 2010
@@ -44,8 +44,14 @@
 
     virtual bool runOnFunction(Function &F) {
       bool Changed = false;
+      
+      DominatorTree &DT = getAnalysis<DominatorTree>();
+      
       for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
-        Changed |= runOnBasicBlock(*I);
+        // Only check non-dead blocks.  Dead blocks may have strange pointer
+        // cycles that will confuse alias analysis.
+        if (DT.isReachableFromEntry(I))
+          Changed |= runOnBasicBlock(*I);
       return Changed;
     }
     

Modified: llvm/trunk/test/Transforms/DeadStoreElimination/crash.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/DeadStoreElimination/crash.ll?rev=95852&r1=95851&r2=95852&view=diff

==============================================================================
--- llvm/trunk/test/Transforms/DeadStoreElimination/crash.ll (original)
+++ llvm/trunk/test/Transforms/DeadStoreElimination/crash.ll Wed Feb 10 23:11:54 2010
@@ -41,3 +41,17 @@
 }
 
 declare void @llvm.memcpy.i64(i8* nocapture, i8* nocapture, i64, i32) nounwind
+
+
+; rdar://7635088
+define i32 @test3() {
+entry:
+  ret i32 0
+  
+dead:
+  %P2 = getelementptr i32 *%P2, i32 52
+  %Q2 = getelementptr i32 *%Q2, i32 52
+  store i32 4, i32* %P2
+  store i32 4, i32* %Q2
+  br label %dead
+}
\ No newline at end of file