Enhance GVN to propagate simple conditionals. This fixes PR3921.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68172 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 52 insertions, 0 deletions

diff --git a/test/Transforms/GVN/condprop.ll b/test/Transforms/GVN/condprop.ll
new file mode 100644
index 0000000..53cbb50
--- /dev/null
+++ b/test/Transforms/GVN/condprop.ll
@@ -0,0 +1,52 @@
+; RUN: llvm-as < %s | opt -gvn | llvm-dis | grep {br i1 false}
+
+@a = external global i32		; <i32*> [#uses=7]
+
+define i32 @foo() nounwind {
+entry:
+	%0 = load i32* @a, align 4		; <i32> [#uses=1]
+	%1 = icmp eq i32 %0, 4		; <i1> [#uses=1]
+	br i1 %1, label %bb, label %bb1
+
+bb:		; preds = %entry
+	br label %bb8
+
+bb1:		; preds = %entry
+	%2 = load i32* @a, align 4		; <i32> [#uses=1]
+	%3 = icmp eq i32 %2, 5		; <i1> [#uses=1]
+	br i1 %3, label %bb2, label %bb3
+
+bb2:		; preds = %bb1
+	br label %bb8
+
+bb3:		; preds = %bb1
+	%4 = load i32* @a, align 4		; <i32> [#uses=1]
+	%5 = icmp eq i32 %4, 4		; <i1> [#uses=1]
+	br i1 %5, label %bb4, label %bb5
+
+bb4:		; preds = %bb3
+	%6 = load i32* @a, align 4		; <i32> [#uses=1]
+	%7 = add i32 %6, 5		; <i32> [#uses=1]
+	br label %bb8
+
+bb5:		; preds = %bb3
+	%8 = load i32* @a, align 4		; <i32> [#uses=1]
+	%9 = icmp eq i32 %8, 5		; <i1> [#uses=1]
+	br i1 %9, label %bb6, label %bb7
+
+bb6:		; preds = %bb5
+	%10 = load i32* @a, align 4		; <i32> [#uses=1]
+	%11 = add i32 %10, 4		; <i32> [#uses=1]
+	br label %bb8
+
+bb7:		; preds = %bb5
+	%12 = load i32* @a, align 4		; <i32> [#uses=1]
+	br label %bb8
+
+bb8:		; preds = %bb7, %bb6, %bb4, %bb2, %bb
+	%.0 = phi i32 [ %12, %bb7 ], [ %11, %bb6 ], [ %7, %bb4 ], [ 4, %bb2 ], [ 5, %bb ]		; <i32> [#uses=1]
+	br label %return
+
+return:		; preds = %bb8
+	ret i32 %.0
+}