1; NOTE: Assertions have been autogenerated by utils/update_test_checks.py 2; RUN: opt < %s -passes=instcombine -S | FileCheck %s 3 4target datalayout = "p:32:32" 5 6%S = type { [2 x i32] } 7 8define i1 @test(ptr %p, i32 %n) { 9; CHECK-LABEL: @test( 10; CHECK-NEXT: [[END:%.*]] = getelementptr inbounds [0 x %S], ptr [[P:%.*]], i32 0, i32 [[N:%.*]], i32 0, i32 0 11; CHECK-NEXT: [[LAST:%.*]] = getelementptr inbounds i8, ptr [[END]], i32 -8 12; CHECK-NEXT: [[CMP:%.*]] = icmp eq ptr [[LAST]], [[P]] 13; CHECK-NEXT: ret i1 [[CMP]] 14; 15 %end = getelementptr inbounds [0 x %S], ptr %p, i32 0, i32 %n, i32 0, i32 0 16 %last = getelementptr inbounds %S, ptr %end, i32 -1 17 %cmp = icmp eq ptr %last, %p 18 ret i1 %cmp 19} 20 21; Same test using 64-bit indices. 22define i1 @test64(ptr %p, i64 %n) { 23; CHECK-LABEL: @test64( 24; CHECK-NEXT: [[TMP1:%.*]] = trunc i64 [[N:%.*]] to i32 25; CHECK-NEXT: [[END:%.*]] = getelementptr inbounds [0 x %S], ptr [[P:%.*]], i32 0, i32 [[TMP1]], i32 0, i32 0 26; CHECK-NEXT: [[LAST:%.*]] = getelementptr inbounds i8, ptr [[END]], i32 -8 27; CHECK-NEXT: [[CMP:%.*]] = icmp eq ptr [[LAST]], [[P]] 28; CHECK-NEXT: ret i1 [[CMP]] 29; 30 %end = getelementptr inbounds [0 x %S], ptr %p, i64 0, i64 %n, i32 0, i64 0 31 %last = getelementptr inbounds %S, ptr %end, i64 -1 32 %cmp = icmp eq ptr %last, %p 33 ret i1 %cmp 34} 35 36; Here the offset overflows and is treated modulo 2^32. This is UB. 37define i1 @test64_overflow(ptr %p, i64 %n) { 38; CHECK-LABEL: @test64_overflow( 39; CHECK-NEXT: [[TMP1:%.*]] = trunc i64 [[N:%.*]] to i32 40; CHECK-NEXT: [[END:%.*]] = getelementptr inbounds [0 x %S], ptr [[P:%.*]], i32 0, i32 [[TMP1]], i32 0, i32 0 41; CHECK-NEXT: [[LAST:%.*]] = getelementptr inbounds i8, ptr [[END]], i32 -8 42; CHECK-NEXT: [[CMP:%.*]] = icmp eq ptr [[LAST]], [[P]] 43; CHECK-NEXT: ret i1 [[CMP]] 44; 45 %end = getelementptr inbounds [0 x %S], ptr %p, i64 0, i64 %n, i32 0, i64 8589934592 46 %last = getelementptr inbounds %S, ptr %end, i64 -1 47 %cmp = icmp eq ptr %last, %p 48 ret i1 %cmp 49} 50