Make sure SimplifyStoreAtEndOfBlock doesn't mess with loops; the

structure checks are incorrect if the blocks aren't distinct.
Fixes PR2435.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52257 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index c04df4a749b560fc8afaae021f5359a787390889..8dbca0f2e8b1501053d54960b0c7611b1e7f40ac 100644 (file)
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -10379,8 +10379,12 @@ bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
   }
   if (++PI != pred_end(DestBB))
     return false;
-  
-  
+
+  // Bail out if all the relevant blocks aren't distinct (this can happen,
+  // for example, if SI is in an infinite loop)
+  if (StoreBB == DestBB || OtherBB == DestBB)
+    return false;
+
   // Verify that the other block ends in a branch and is not otherwise empty.
   BasicBlock::iterator BBI = OtherBB->getTerminator();
   BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);

diff --git a/test/Transforms/InstCombine/2008-06-13-InfiniteLoopStore.ll b/test/Transforms/InstCombine/2008-06-13-InfiniteLoopStore.ll
new file mode 100644 (file)
index 0000000..674042a
--- /dev/null
+++ b/test/Transforms/InstCombine/2008-06-13-InfiniteLoopStore.ll
@@ -0,0 +1,22 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {store i32} | count 2
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+target triple = "i386-apple-darwin8"
+
+@g_139 = global i32 0           ; <i32*> [#uses=2]
+
+define void @func_56(i32 %p_60) nounwind  {
+entry:
+        store i32 1, i32* @g_139, align 4
+        %tmp1 = icmp ne i32 %p_60, 0            ; <i1> [#uses=1]
+        %tmp12 = zext i1 %tmp1 to i8            ; <i8> [#uses=1]
+        %toBool = icmp ne i8 %tmp12, 0          ; <i1> [#uses=1]
+        br i1 %toBool, label %bb, label %return
+
+bb:             ; preds = %bb, %entry
+        store i32 1, i32* @g_139, align 4
+        br label %bb
+
+return:         ; preds = %entry
+        ret void
+}
+