From 4c332fa5a5a650cd779935d78b505f84cef4db69 Mon Sep 17 00:00:00 2001
From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Fri, 20 Sep 2013 14:38:44 +0000
Subject: InstCombine: Canonicalize (gep i8* X, -(ptrtoint Y)) to (sub
 (ptrtoint X), (ptrtoint Y))

The GEP pattern is what SCEV expander emits for "ugly geps". The latter is what
you get for pointer subtraction in C code. The rest of instcombine already
knows how to deal with that so just canonicalize on that.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191090 91177308-0d34-0410-b5e6-96231b3b80d8
---
 test/Transforms/InstCombine/getelementptr.ll | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

(limited to 'test')

diff --git a/test/Transforms/InstCombine/getelementptr.ll b/test/Transforms/InstCombine/getelementptr.ll
index ff8ad63..191a151 100644
--- a/test/Transforms/InstCombine/getelementptr.ll
+++ b/test/Transforms/InstCombine/getelementptr.ll
@@ -762,4 +762,18 @@ define i8 @test_gep_bitcast_array_different_size_element_as1([100 x double] addr
   ret i8 %x
 }
 
+define i64 @test40() {
+  %array = alloca [3 x i32], align 4
+  %gep = getelementptr inbounds [3 x i32]* %array, i64 0, i64 2
+  %gepi8 = bitcast i32* %gep to i8*
+  %p = ptrtoint [3 x i32]* %array to i64
+  %np = sub i64 0, %p
+  %gep2 = getelementptr i8* %gepi8, i64 %np
+  %ret = ptrtoint i8* %gep2 to i64
+  ret i64 %ret
+
+; CHECK-LABEL: @test40
+; CHECK-NEXT: ret i64 8
+}
+
 ; CHECK: attributes [[NUW]] = { nounwind }
-- 
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