1; RUN: opt -O2 -mtriple=bpf-pc-linux -S -o - %s | FileCheck %s 2; 3; Check that bpf-preserve-static-offset folds chain of GEP instructions. 4; The GEP chain in this example has type mismatch and thus is 5; folded as i8 access. 6; 7; Source: 8; #define __ctx __attribute__((preserve_static_offset)) 9; 10; struct foo { 11; char aa; 12; char bb; 13; }; 14; 15; struct bar { 16; char a; 17; struct foo b; 18; } __ctx; 19; 20; void buz(struct bar *p) { 21; ((struct foo *)(((char*)&p->b) + 1))->bb = 42; 22; } 23; 24; Compilation flag: 25; clang -cc1 -O2 -triple bpf -S -emit-llvm -disable-llvm-passes -o - \ 26; | opt -passes=function(sroa) -S -o - 27 28%struct.bar = type { i8, %struct.foo } 29%struct.foo = type { i8, i8 } 30 31; Function Attrs: nounwind 32define dso_local void @buz(ptr noundef %p) #0 { 33entry: 34 %0 = call ptr @llvm.preserve.static.offset(ptr %p) 35 %b = getelementptr inbounds %struct.bar, ptr %0, i32 0, i32 1 36 %add.ptr = getelementptr inbounds i8, ptr %b, i64 1 37; ~~ 38; these types do not match, thus GEP chain is folded as an offset 39; ~~~~~~~~~~~ 40 %bb = getelementptr inbounds %struct.foo, ptr %add.ptr, i32 0, i32 1 41 store i8 42, ptr %bb, align 1, !tbaa !2 42 ret void 43} 44 45; CHECK: define dso_local void @buz(ptr noundef writeonly captures(none) %[[p:.*]]) 46; CHECK: tail call void (i8, ptr, i1, i8, i8, i8, i1, ...) 47; CHECK-SAME: @llvm.bpf.getelementptr.and.store.i8 48; CHECK-SAME: (i8 42, 49; CHECK-SAME: ptr writeonly elementtype(i8) %[[p]], 50; CHECK-SAME: i1 false, i8 0, i8 1, i8 0, i1 true, i64 immarg 3) 51; CHECK-SAME: #[[v2:.*]], !tbaa ![[v3:.*]] 52; CHECK: attributes #[[v2]] = { memory(argmem: write) } 53 54; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none) 55declare ptr @llvm.preserve.static.offset(ptr readnone) #1 56 57attributes #0 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" } 58attributes #1 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) } 59 60!llvm.module.flags = !{!0} 61!llvm.ident = !{!1} 62 63!0 = !{i32 1, !"wchar_size", i32 4} 64!1 = !{!"clang"} 65!2 = !{!3, !4, i64 1} 66!3 = !{!"foo", !4, i64 0, !4, i64 1} 67!4 = !{!"omnipotent char", !5, i64 0} 68!5 = !{!"Simple C/C++ TBAA"} 69