Handle single-entry phi nodes gracefully in condprop.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62985 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/CondPropagate.cpp b/lib/Transforms/Scalar/CondPropagate.cpp
index 2e899432909e32e502bea65c93090b2adf295d7e..f68fb292e4a909a70d59ec41a14628f0f484ca47 100644 (file)
--- a/lib/Transforms/Scalar/CondPropagate.cpp
+++ b/lib/Transforms/Scalar/CondPropagate.cpp
@@ -126,6 +126,14 @@ void CondProp::SimplifyPredecessors(BranchInst *BI) {
   // one use (the branch), and is the only instruction besides the branch in the
   // block.
   PHINode *PN = cast<PHINode>(BI->getCondition());
+
+  if (PN->getNumIncomingValues() == 1) {
+    // Eliminate single-entry PHI nodes.
+    FoldSingleEntryPHINodes(PN->getParent());
+    return;
+  }
+  
+  
   if (!PN->hasOneUse()) return;
 
   BasicBlock *BB = BI->getParent();

diff --git a/test/Transforms/CondProp/2009-01-25-SingleEntryPHI.ll b/test/Transforms/CondProp/2009-01-25-SingleEntryPHI.ll
new file mode 100644 (file)
index 0000000..d14ce38
--- /dev/null
+++ b/test/Transforms/CondProp/2009-01-25-SingleEntryPHI.ll
@@ -0,0 +1,37 @@
+; RUN: llvm-as < %s | opt -condprop | llvm-dis
+; PR3405
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @main(i32 %argc, i8** %argv) nounwind {
+entry:
+       br label %bb2
+
+bb2:           ; preds = %bb.bb2_crit_edge, %entry
+       br i1 false, label %bb5.thread2, label %bb
+
+bb:            ; preds = %bb2
+       br i1 false, label %bb3, label %bb.bb2_crit_edge
+
+bb.bb2_crit_edge:              ; preds = %bb
+       br label %bb2
+
+bb3:           ; preds = %bb
+       %.lcssa4 = phi i1 [ false, %bb ]                ; <i1> [#uses=1]
+       br i1 %.lcssa4, label %bb5.thread, label %bb6
+
+bb5.thread:            ; preds = %bb3
+       br label %bb7
+
+bb7:           ; preds = %bb5.thread2, %bb5.thread
+       br label %UnifiedReturnBlock
+
+bb6:           ; preds = %bb3
+       br label %UnifiedReturnBlock
+
+bb5.thread2:           ; preds = %bb2
+       br label %bb7
+
+UnifiedReturnBlock:            ; preds = %bb6, %bb7
+       ret i32 0
+}