[CodeGenPrepare] Fix crash due to an invalid CFG
The splitIndirectCriticalEdges function generates and invalid CFG when the
'Target' basic block is a loop to itself. When this occurs, the code that
updates the predecessor terminator needs to update the terminator in the split
basic block.
This occurs when there is an edge from block D back to D. Since D is split in
to D0 and D1, the code needs to update the terminator in D1. But D1 is not in
the OtherPreds vector, so it was not getting updated.
Differential Revision: https://reviews.llvm.org/D32126
llvm-svn: 300480
diff --git a/llvm/test/Transforms/CodeGenPrepare/split-indirect-loop.ll b/llvm/test/Transforms/CodeGenPrepare/split-indirect-loop.ll
new file mode 100644
index 0000000..cb834bb
--- /dev/null
+++ b/llvm/test/Transforms/CodeGenPrepare/split-indirect-loop.ll
@@ -0,0 +1,37 @@
+; RUN: opt -codegenprepare -S < %s | FileCheck %s
+
+; Test that an invalid CFG is not created by splitIndirectCriticalEdges
+; transformation when the 'target' block is a loop to itself.
+
+; CHECK: .split:
+; CHECK: br label %while.body.clone
+; CHECK: if.else1:
+; CHECK: indirectbr
+; CHECK: while.body.clone:
+; CHECK: br label %.split
+
+define void @test() {
+entry:
+ br label %if.else
+
+if.else:
+ br i1 undef, label %while.body, label %preheader
+
+preheader:
+ br label %if.else1
+
+if.then:
+ unreachable
+
+while.body:
+ %dest.sroa = phi i32 [ %1, %while.body ], [ undef, %if.else1 ], [ undef, %if.else ]
+ %0 = inttoptr i32 %dest.sroa to i8*
+ %incdec.ptr = getelementptr inbounds i8, i8* %0, i32 -1
+ %1 = ptrtoint i8* %incdec.ptr to i32
+ store i8 undef, i8* %incdec.ptr, align 1
+ br label %while.body
+
+if.else1:
+ indirectbr i8* undef, [label %if.then, label %while.body, label %if.else, label %if.else1]
+}
+