Implement PR1786 by iterating between dead cycle elimination

and simplifycfg in the rare cases when it is needed.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44044 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 100 insertions, 0 deletions

diff --git a/test/Transforms/SimplifyCFG/iterative-simplify.ll b/test/Transforms/SimplifyCFG/iterative-simplify.ll
new file mode 100644
index 0000000000..9081b01b20
--- /dev/null
+++ b/test/Transforms/SimplifyCFG/iterative-simplify.ll
@@ -0,0 +1,100 @@
+; RUN: llvm-as < %s | opt -simplifycfg | llvm-dis | not grep bb17
+; PR1786
+
+define i32 @main() {
+entry:
+	%retval = alloca i32, align 4		; <i32*> [#uses=1]
+	%i = alloca i32, align 4		; <i32*> [#uses=7]
+	%z = alloca i32, align 4		; <i32*> [#uses=4]
+	%z16 = alloca i32, align 4		; <i32*> [#uses=4]
+	%"alloca point" = bitcast i32 0 to i32		; <i32> [#uses=0]
+	store i32 0, i32* %i
+	%toBool = icmp ne i8 1, 0		; <i1> [#uses=1]
+	br i1 %toBool, label %cond_true, label %cond_false
+
+cond_true:		; preds = %entry
+	store i32 0, i32* %z
+	br label %bb
+
+bb:		; preds = %cond_next, %cond_true
+	%tmp = load i32* %z		; <i32> [#uses=1]
+	%tmp1 = sub i32 %tmp, 16384		; <i32> [#uses=1]
+	store i32 %tmp1, i32* %z
+	%tmp2 = load i32* %i		; <i32> [#uses=1]
+	%tmp3 = add i32 %tmp2, 1		; <i32> [#uses=1]
+	store i32 %tmp3, i32* %i
+	%tmp4 = load i32* %i		; <i32> [#uses=1]
+	%tmp5 = icmp sgt i32 %tmp4, 262144		; <i1> [#uses=1]
+	%tmp56 = zext i1 %tmp5 to i8		; <i8> [#uses=1]
+	%toBool7 = icmp ne i8 %tmp56, 0		; <i1> [#uses=1]
+	br i1 %toBool7, label %cond_true8, label %cond_next
+
+cond_true8:		; preds = %bb
+	call void @abort( )
+	unreachable
+
+cond_next:		; preds = %bb
+	%tmp9 = load i32* %z		; <i32> [#uses=1]
+	%tmp10 = icmp ne i32 %tmp9, 0		; <i1> [#uses=1]
+	%tmp1011 = zext i1 %tmp10 to i8		; <i8> [#uses=1]
+	%toBool12 = icmp ne i8 %tmp1011, 0		; <i1> [#uses=1]
+	br i1 %toBool12, label %bb, label %bb13
+
+bb13:		; preds = %cond_next
+	call void @exit( i32 0 )
+	unreachable
+
+cond_false:		; preds = %entry
+	%toBool14 = icmp ne i8 1, 0		; <i1> [#uses=1]
+	br i1 %toBool14, label %cond_true15, label %cond_false33
+
+cond_true15:		; preds = %cond_false
+	store i32 0, i32* %z16
+	br label %bb17
+
+bb17:		; preds = %cond_next27, %cond_true15
+	%tmp18 = load i32* %z16		; <i32> [#uses=1]
+	%tmp19 = sub i32 %tmp18, 16384		; <i32> [#uses=1]
+	store i32 %tmp19, i32* %z16
+	%tmp20 = load i32* %i		; <i32> [#uses=1]
+	%tmp21 = add i32 %tmp20, 1		; <i32> [#uses=1]
+	store i32 %tmp21, i32* %i
+	%tmp22 = load i32* %i		; <i32> [#uses=1]
+	%tmp23 = icmp sgt i32 %tmp22, 262144		; <i1> [#uses=1]
+	%tmp2324 = zext i1 %tmp23 to i8		; <i8> [#uses=1]
+	%toBool25 = icmp ne i8 %tmp2324, 0		; <i1> [#uses=1]
+	br i1 %toBool25, label %cond_true26, label %cond_next27
+
+cond_true26:		; preds = %bb17
+	call void @abort( )
+	unreachable
+
+cond_next27:		; preds = %bb17
+	%tmp28 = load i32* %z16		; <i32> [#uses=1]
+	%tmp29 = icmp ne i32 %tmp28, 0		; <i1> [#uses=1]
+	%tmp2930 = zext i1 %tmp29 to i8		; <i8> [#uses=1]
+	%toBool31 = icmp ne i8 %tmp2930, 0		; <i1> [#uses=1]
+	br i1 %toBool31, label %bb17, label %bb32
+
+bb32:		; preds = %cond_next27
+	call void @exit( i32 0 )
+	unreachable
+
+cond_false33:		; preds = %cond_false
+	call void @exit( i32 0 )
+	unreachable
+
+cond_next34:		; No predecessors!
+	br label %cond_next35
+
+cond_next35:		; preds = %cond_next34
+	br label %return
+
+return:		; preds = %cond_next35
+	%retval36 = load i32* %retval		; <i32> [#uses=1]
+	ret i32 %retval36
+}
+
+declare void @abort()
+
+declare void @exit(i32)