1 files changed, 48 insertions, 0 deletions
diff --git a/test/Transforms/InstSimplify/ptr_diff.ll b/test/Transforms/InstSimplify/ptr_diff.ll
new file mode 100644
index 0000000..1eb1fd4
--- /dev/null
+++ b/test/Transforms/InstSimplify/ptr_diff.ll
@@ -0,0 +1,48 @@
+; RUN: opt < %s -instsimplify -S | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i64 @ptrdiff1(i8* %ptr) {
+; CHECK: @ptrdiff1
+; CHECK-NEXT: ret i64 42
+
+  %first = getelementptr inbounds i8* %ptr, i32 0
+  %last = getelementptr inbounds i8* %ptr, i32 42
+  %first.int = ptrtoint i8* %first to i64
+  %last.int = ptrtoint i8* %last to i64
+  %diff = sub i64 %last.int, %first.int
+  ret i64 %diff
+}
+
+define i64 @ptrdiff2(i8* %ptr) {
+; CHECK: @ptrdiff2
+; CHECK-NEXT: ret i64 42
+
+  %first1 = getelementptr inbounds i8* %ptr, i32 0
+  %first2 = getelementptr inbounds i8* %first1, i32 1
+  %first3 = getelementptr inbounds i8* %first2, i32 2
+  %first4 = getelementptr inbounds i8* %first3, i32 4
+  %last1 = getelementptr inbounds i8* %first2, i32 48
+  %last2 = getelementptr inbounds i8* %last1, i32 8
+  %last3 = getelementptr inbounds i8* %last2, i32 -4
+  %last4 = getelementptr inbounds i8* %last3, i32 -4
+  %first.int = ptrtoint i8* %first4 to i64
+  %last.int = ptrtoint i8* %last4 to i64
+  %diff = sub i64 %last.int, %first.int
+  ret i64 %diff
+}
+
+define i64 @ptrdiff3(i8* %ptr) {
+; Don't bother with non-inbounds GEPs.
+; CHECK: @ptrdiff3
+; CHECK: getelementptr
+; CHECK: sub
+; CHECK: ret
+
+  %first = getelementptr i8* %ptr, i32 0
+  %last = getelementptr i8* %ptr, i32 42
+  %first.int = ptrtoint i8* %first to i64
+  %last.int = ptrtoint i8* %last to i64
+  %diff = sub i64 %last.int, %first.int
+  ret i64 %diff
+}