Fold fptrunc(add (fpextend x), (fpextend y)) -> add(x,y), as GCC does.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46406 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 36 insertions, 0 deletions

diff --git a/test/Transforms/InstCombine/fpextend.ll b/test/Transforms/InstCombine/fpextend.ll
new file mode 100644
index 0000000000..5971080cef
--- /dev/null
+++ b/test/Transforms/InstCombine/fpextend.ll
@@ -0,0 +1,36 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep fpext
+@X = external global float 
+@Y = external global float
+
+define void @test() nounwind  {
+entry:
+	%tmp = load float* @X, align 4		; <float> [#uses=1]
+	%tmp1 = fpext float %tmp to double		; <double> [#uses=1]
+	%tmp3 = add double %tmp1, 0.000000e+00		; <double> [#uses=1]
+	%tmp34 = fptrunc double %tmp3 to float		; <float> [#uses=1]
+	store float %tmp34, float* @X, align 4
+	ret void
+}
+
+define void @test3() nounwind  {
+entry:
+	%tmp = load float* @X, align 4		; <float> [#uses=1]
+	%tmp1 = fpext float %tmp to double		; <double> [#uses=1]
+	%tmp2 = load float* @Y, align 4		; <float> [#uses=1]
+	%tmp23 = fpext float %tmp2 to double		; <double> [#uses=1]
+	%tmp5 = fdiv double %tmp1, %tmp23		; <double> [#uses=1]
+	%tmp56 = fptrunc double %tmp5 to float		; <float> [#uses=1]
+	store float %tmp56, float* @X, align 4
+	ret void
+}
+
+define void @test4() nounwind  {
+entry:
+	%tmp = load float* @X, align 4		; <float> [#uses=1]
+	%tmp1 = fpext float %tmp to double		; <double> [#uses=1]
+	%tmp2 = sub double -0.000000e+00, %tmp1		; <double> [#uses=1]
+	%tmp34 = fptrunc double %tmp2 to float		; <float> [#uses=1]
+	store float %tmp34, float* @X, align 4
+	ret void
+}
+