Fix simplifycfg crash in handing block merge.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@55971 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Utils/BasicBlockUtils.cpp b/lib/Transforms/Utils/BasicBlockUtils.cpp
index 719bc8a34f8325af7a1bf98304b9b3de082bdfef..a98e1356ad3ebfef8fd06712b9669574e6c3689c 100644 (file)
--- a/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -54,7 +54,17 @@ bool llvm::MergeBlockIntoPredecessor(BasicBlock* BB, Pass* P) {
   
   // Can't merge if there are multiple successors.
   if (!OnlySucc) return false;
-  
+
+  // Can't merge if there is PHI loop.
+  for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE; ++BI) {
+    if (PHINode *PN = dyn_cast<PHINode>(BI)) {
+      for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+        if (PN->getIncomingValue(i) == PN)
+          return false;
+    } else
+      break;
+  }
+
   // Begin by getting rid of unneeded PHIs.
   while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
     PN->replaceAllUsesWith(PN->getIncomingValue(0));

diff --git a/test/Transforms/SimplifyCFG/2008-09-08-MultiplePred.ll b/test/Transforms/SimplifyCFG/2008-09-08-MultiplePred.ll
new file mode 100644 (file)
index 0000000..82a2cc0
--- /dev/null
+++ b/test/Transforms/SimplifyCFG/2008-09-08-MultiplePred.ll
@@ -0,0 +1,60 @@
+; RUN: llvm-as < %s | opt -simplifycfg -disable-output
+; PR 2777
+@g_103 = common global i32 0           ; <i32*> [#uses=1]
+
+define i32 @func_127(i32 %p_129) nounwind {
+entry:
+       load i32* @g_103, align 4               ; <i32>:0 [#uses=1]
+       icmp eq i32 %0, 0               ; <i1>:1 [#uses=2]
+       br i1 %1, label %bb6.preheader, label %entry.return_crit_edge
+
+entry.return_crit_edge:                ; preds = %entry
+       br label %return
+
+bb6.preheader:         ; preds = %entry
+       br i1 %1, label %bb6.preheader.split.us, label %bb6.preheader.split
+
+bb6.preheader.split.us:                ; preds = %bb6.preheader
+       br label %return.loopexit.split
+
+bb6.preheader.split:           ; preds = %bb6.preheader
+       br label %bb6
+
+bb6:           ; preds = %bb17.bb6_crit_edge, %bb6.preheader.split
+       %indvar35 = phi i32 [ 0, %bb6.preheader.split ], [ %indvar.next36, %bb17.bb6_crit_edge ]                ; <i32> [#uses=1]
+       %p_129_addr.3.reg2mem.0 = phi i32 [ %p_129_addr.2, %bb17.bb6_crit_edge ], [ %p_129, %bb6.preheader.split ]              ; <i32> [#uses=3]
+       icmp eq i32 %p_129_addr.3.reg2mem.0, 0          ; <i1>:2 [#uses=1]
+       br i1 %2, label %bb6.bb17_crit_edge, label %bb8
+
+bb6.bb17_crit_edge:            ; preds = %bb6
+       br label %bb17
+
+bb8:           ; preds = %bb6
+       br label %bb13
+
+bb13:          ; preds = %bb8
+       br label %bb17
+
+bb17:          ; preds = %bb13, %bb6.bb17_crit_edge
+       %p_129_addr.2 = phi i32 [ %p_129_addr.3.reg2mem.0, %bb13 ], [ %p_129_addr.3.reg2mem.0, %bb6.bb17_crit_edge ]            ; <i32> [#uses=1]
+       %indvar.next36 = add i32 %indvar35, 1           ; <i32> [#uses=2]
+       %exitcond37 = icmp eq i32 %indvar.next36, -1            ; <i1> [#uses=1]
+       br i1 %exitcond37, label %return.loopexit, label %bb17.bb6_crit_edge
+
+bb17.bb6_crit_edge:            ; preds = %bb17
+       br label %bb6
+
+return.loopexit:               ; preds = %bb17
+       br label %return.loopexit.split
+
+return.loopexit.split:         ; preds = %return.loopexit, %bb6.preheader.split.us
+       br label %return
+
+return:                ; preds = %return.loopexit.split, %entry.return_crit_edge
+       ret i32 1
+}
+
+define i32 @func_135(i8 zeroext %p_137, i32 %p_138, i32 %p_140) nounwind {
+entry:
+       ret i32 undef
+}