1 files changed, 100 insertions, 0 deletions
diff --git a/llvm/test/Transforms/InstCombine/indexed-gep-compares.ll b/llvm/test/Transforms/InstCombine/indexed-gep-compares.ll
new file mode 100644
index 00000000000..fab0d309e4a
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/indexed-gep-compares.ll
@@ -0,0 +1,100 @@
+; RUN: opt -instcombine -S  < %s | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:32-f32:32:32-f64:32:32-v64:64:64-v128:128:128-a0:0:64"
+
+define i32 *@test1(i32* %A, i32 %Offset) {
+entry:
+  %tmp = getelementptr inbounds i32, i32* %A, i32 %Offset
+  br label %bb
+
+bb:
+  %RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %entry ]
+  %LHS = getelementptr inbounds i32, i32* %A, i32 100
+  %RHS.next = getelementptr inbounds i32, i32* %RHS, i64 1
+  %cond = icmp ult i32 * %LHS, %RHS
+  br i1 %cond, label %bb2, label %bb
+
+bb2:
+  ret i32* %RHS
+
+; CHECK-LABEL: @test1(
+; CHECK:  %[[INDEX:[0-9A-Za-z.]+]] = phi i32 [ %[[ADD:[0-9A-Za-z.]+]], %bb ], [ %Offset, %entry ]
+; CHECK:  %[[ADD]] = add i32 %[[INDEX]], 1
+; CHECK:  %cond = icmp sgt i32 %[[INDEX]], 100
+; CHECK:  br i1 %cond, label %bb2, label %bb
+; CHECK:  %[[PTR:[0-9A-Za-z.]+]] = getelementptr inbounds i32, i32* %A, i32 %[[INDEX]]
+; CHECK:  ret i32* %[[PTR]]
+}
+
+define i32 *@test2(i32 %A, i32 %Offset) {
+entry:
+  %A.ptr = inttoptr i32 %A to i32*
+  %tmp = getelementptr inbounds i32, i32* %A.ptr, i32 %Offset
+  br label %bb
+
+bb:
+  %RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %entry ]
+  %LHS = getelementptr inbounds i32, i32* %A.ptr, i32 100
+  %RHS.next = getelementptr inbounds i32, i32* %RHS, i64 1
+  %cmp0 = ptrtoint i32 *%LHS to i32
+  %cmp1 = ptrtoint i32 *%RHS to i32
+  %cond = icmp ult i32 %cmp0, %cmp1
+  br i1 %cond, label %bb2, label %bb
+
+bb2:
+  ret i32* %RHS
+
+; CHECK-LABEL: @test2(
+; CHECK:  %[[TOPTR:[0-9A-Za-z.]+]] = inttoptr i32 %[[ADD:[0-9A-Za-z.]+]] to i32*
+; CHECK:  %[[INDEX:[0-9A-Za-z.]+]] = phi i32 [ %[[ADD:[0-9A-Za-z.]+]], %bb ], [ %Offset, %entry ]
+; CHECK:  %[[ADD]] = add i32 %[[INDEX]], 1
+; CHECK:  %cond = icmp sgt i32 %[[INDEX]], 100
+; CHECK:  br i1 %cond, label %bb2, label %bb
+; CHECK:  %[[PTR:[0-9A-Za-z.]+]] = getelementptr inbounds i32, i32* %[[TOPTR]], i32 %[[INDEX]]
+; CHECK:  ret i32* %[[PTR]]
+}
+
+; Perform the transformation only if we know that the GEPs used are inbounds.
+define i32 *@test3(i32* %A, i32 %Offset) {
+entry:
+  %tmp = getelementptr i32, i32* %A, i32 %Offset
+  br label %bb
+
+bb:
+  %RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %entry ]
+  %LHS = getelementptr i32, i32* %A, i32 100
+  %RHS.next = getelementptr i32, i32* %RHS, i64 1
+  %cond = icmp ult i32 * %LHS, %RHS
+  br i1 %cond, label %bb2, label %bb
+
+bb2:
+  ret i32* %RHS
+
+; CHECK-LABEL: @test3(
+; CHECK-NOT:  %cond = icmp sgt i32 %{{[0-9A-Za-z.]+}}, 100
+}
+
+; An inttoptr that requires an extension or truncation will be opaque when determining
+; the base pointer. In this case we can still perform the transformation by considering
+; A.ptr as being the base pointer.
+define i32 *@test4(i16 %A, i32 %Offset) {
+entry:
+  %A.ptr = inttoptr i16 %A to i32*
+  %tmp = getelementptr inbounds i32, i32* %A.ptr, i32 %Offset
+  br label %bb
+
+bb:
+  %RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %entry ]
+  %LHS = getelementptr inbounds i32, i32* %A.ptr, i32 100
+  %RHS.next = getelementptr inbounds i32, i32* %RHS, i64 1
+  %cmp0 = ptrtoint i32 *%LHS to i32
+  %cmp1 = ptrtoint i32 *%RHS to i32
+  %cond = icmp ult i32 %cmp0, %cmp1
+  br i1 %cond, label %bb2, label %bb
+
+bb2:
+  ret i32* %RHS
+
+; CHECK-LABEL: @test4(
+; CHECK:  %cond = icmp sgt i32 %{{[0-9A-Za-z.]+}}, 100
+}