maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
llvm-project/clang/test/CodeGen/bpf-attr-preserve-access-in...

Ignoring revisions in .git-blame-ignore-revs. Click here to bypass and see the normal blame view.

25 lines
949 B
C
Raw Normal View History

[BPF] Add preserve_access_index attribute for record definition This is a resubmission for the previous reverted commit 943436040121 with the same subject. This commit fixed the segfault issue and addressed additional review comments. This patch introduced a new bpf specific attribute which can be added to struct or union definition. For example, struct s { ... } __attribute__((preserve_access_index)); union u { ... } __attribute__((preserve_access_index)); The goal is to simplify user codes for cases where preserve access index happens for certain struct/union, so user does not need to use clang __builtin_preserve_access_index for every members. The attribute has no effect if -g is not specified. When the attribute is specified and -g is specified, any member access defined by that structure or union, including array subscript access and inner records, will be preserved through __builtin_preserve_{array,struct,union}_access_index() IR intrinsics, which will enable relocation generation in bpf backend. The following is an example to illustrate the usage: -bash-4.4$ cat t.c #define __reloc__ __attribute__((preserve_access_index)) struct s1 { int c; } __reloc__; struct s2 { union { struct s1 b[3]; }; } __reloc__; struct s3 { struct s2 a; } __reloc__; int test(struct s3 *arg) { return arg->a.b[2].c; } -bash-4.4$ clang -target bpf -g -S -O2 t.c A relocation with access string "0:0:0:0:2:0" will be generated representing access offset of arg->a.b[2].c. forward declaration with attribute is also handled properly such that the attribute is copied and populated in real record definition. Differential Revision: https://reviews.llvm.org/D69759
2019-11-02 13:16:59 +08:00
// REQUIRES: bpf-registered-target
// RUN: %clang -target bpf -emit-llvm -S -g %s -o - | FileCheck %s
#define __reloc__ __attribute__((preserve_access_index))
// test array access
struct s1 {
int a[3];
union {
int b;
int c[4];
};
} __reloc__;
typedef struct s1 __s1;
int test(__s1 *arg) {
return arg->a[2] + arg->c[2];
}
// CHECK: call [3 x i32]* @llvm.preserve.struct.access.index.p0a3i32.p0s_struct.s1s(%struct.s1* %{{[0-9a-z]+}}, i32 0, i32 0)
// CHECK: call i32* @llvm.preserve.array.access.index.p0i32.p0a3i32([3 x i32]* %{{[0-9a-z]+}}, i32 1, i32 2)
// CHECK: call %union.anon* @llvm.preserve.struct.access.index.p0s_union.anons.p0s_struct.s1s(%struct.s1* %{{[0-9a-z]+}}, i32 1, i32 1)
// CHECK: call %union.anon* @llvm.preserve.union.access.index.p0s_union.anons.p0s_union.anons(%union.anon* %{{[0-9a-z]+}}, i32 1)
// CHECK: call i32* @llvm.preserve.array.access.index.p0i32.p0a4i32([4 x i32]* %{{[0-9a-z]+}}, i32 1, i32 2)