From a4b8059ee2e42747fce054bafd502d932e7defa5 Mon Sep 17 00:00:00 2001
From: Roman Lebedev <lebedev.ri@gmail.com>
Date: Wed, 7 Apr 2021 11:50:06 +0300
Subject: [PATCH] [NFC][InstCombine] Add sub-of-sub tests with constant
 expressions

These would cause endless combine loop after 31d219d2997fed1b7dc97e0adf170d5aaf65883e.
---
 test/Transforms/InstCombine/sub-from-sub.ll | 31 +++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/test/Transforms/InstCombine/sub-from-sub.ll b/test/Transforms/InstCombine/sub-from-sub.ll
index 202dbd1072a..0d5885a740f 100644
--- a/test/Transforms/InstCombine/sub-from-sub.ll
+++ b/test/Transforms/InstCombine/sub-from-sub.ll
@@ -168,3 +168,34 @@ define i8 @t12_c1_c2_exrause(i8 %x, i8 %z) {
   %r = sub i8 %i0, 24
   ret i8 %r
 }
+
+; PR49870
+@g0 = external global i8, align 1
+@g1 = external global i8, align 1
+define i32 @constantexpr0(i32 %x, i8* %y) unnamed_addr {
+; CHECK-LABEL: @constantexpr0(
+; CHECK-NEXT:    [[R:%.*]] = sub i32 sub (i32 0, i32 ptrtoint (i8* @g0 to i32)), [[X:%.*]]
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %i0 = add i32 %x, ptrtoint (i8* @g0 to i32)
+  %r = sub i32 0, %i0
+  ret i32 %r
+}
+define i32 @constantexpr1(i32 %x, i8* %y) unnamed_addr {
+; CHECK-LABEL: @constantexpr1(
+; CHECK-NEXT:    [[R:%.*]] = sub i32 sub (i32 ptrtoint (i8* @g1 to i32), i32 42), [[X:%.*]]
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %i0 = add i32 %x, 42
+  %r = sub i32 ptrtoint (i8* @g1 to i32), %i0
+  ret i32 %r
+}
+define i32 @constantexpr2(i32 %x, i8* %y) unnamed_addr {
+; CHECK-LABEL: @constantexpr2(
+; CHECK-NEXT:    [[R:%.*]] = sub i32 sub (i32 ptrtoint (i8* @g1 to i32), i32 ptrtoint (i8* @g0 to i32)), [[X:%.*]]
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %i0 = add i32 %x, ptrtoint (i8* @g0 to i32)
+  %r = sub i32 ptrtoint (i8* @g1 to i32), %i0
+  ret i32 %r
+}