Add a testcase for PR2831.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76527 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/Transforms/InstCombine/cast3.ll b/test/Transforms/InstCombine/cast3.ll
new file mode 100644 (file)
index 0000000..7cb8634
--- /dev/null
+++ b/test/Transforms/InstCombine/cast3.ll
@@ -0,0 +1,35 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep getelementptr
+; PR2831
+
+; Don't raise arbitrary inttoptr+arithmetic+ptrtoint to getelementptr.
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
+
+define i32 @main(i32 %argc, i8** %argv) nounwind {
+entry:
+       %0 = ptrtoint i8** %argv to i32         ; <i32> [#uses=1]
+       %1 = add i32 %0, 1              ; <i32> [#uses=1]
+       ret i32 %1
+}
+
+; This testcase could theoretically be optimized down to return zero,
+; but for now being conservative with ptrtoint/inttoptr is fine.
+define i32 @a() nounwind {
+entry:
+       %b = alloca i32         ; <i32*> [#uses=3]
+       %a = alloca i32         ; <i32*> [#uses=2]
+       %"alloca point" = bitcast i32 0 to i32          ; <i32> [#uses=0]
+       store i32 1, i32* %b, align 4
+       %a1 = ptrtoint i32* %a to i32           ; <i32> [#uses=1]
+       %b4 = ptrtoint i32* %b to i32           ; <i32> [#uses=1]
+       %a7 = ptrtoint i32* %a to i32           ; <i32> [#uses=1]
+       %0 = sub i32 %b4, %a7           ; <i32> [#uses=1]
+       %1 = add i32 %a1, %0            ; <i32> [#uses=1]
+       %2 = inttoptr i32 %1 to i32*            ; <i32*> [#uses=1]
+       store i32 0, i32* %2, align 4
+       %3 = load i32* %b, align 4              ; <i32> [#uses=1]
+       br label %return
+
+return:                ; preds = %entry
+       ret i32 %3
+}