f29955a594
The counted_by attribute currently rejects void* members because void has no defined size. However, the sized_by attribute accepts void* since it explicitly measures bytes. As a GNU extension, void pointer arithmetic treats void as having size 1 byte, so counted_by on void* should behave identically to sized_by (treating the count as bytes). Allow counted_by on void* as a GNU extension. The implementation validates this only at declaration time in SemaBoundsSafety.cpp, emitting a -Wpointer-arith warning that the attribute is treated as a GNU extension equivalent to sized_by. Both use-site validation and code generation trust this earlier validation, avoiding redundant checks. In CodeGen, __builtin_dynamic_object_size now correctly handles counted_by on void* by treating any CountAttributedType with zero element size as having 1-byte elements, matching the GNU void pointer arithmetic semantics. Add tests validating both Sema diagnostics and CodeGen behavior (correct byte counts from __builtin_dynamic_object_size). Update existing counted_by tests to explicitly use -Wpointer-arith to preserve their original intent of rejecting void* in strict C mode.
66 lines
2.4 KiB
C
66 lines
2.4 KiB
C
// RUN: %clang_cc1 -std=gnu11 -triple x86_64-unknown-linux-gnu -O2 -emit-llvm -o - %s | FileCheck %s
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// Test that counted_by on void* in GNU mode treats void as having size 1 (byte count)
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#define __counted_by(f) __attribute__((counted_by(f)))
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#define __sized_by(f) __attribute__((sized_by(f)))
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struct with_counted_by_void {
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int count;
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void* buf __counted_by(count);
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};
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struct with_sized_by_void {
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int size;
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void* buf __sized_by(size);
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};
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struct with_counted_by_int {
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int count;
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int* buf __counted_by(count);
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};
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// CHECK-LABEL: define dso_local {{.*}}@test_counted_by_void(
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// CHECK: %[[COUNT:.*]] = load i32, ptr %s
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// CHECK: %[[NARROW:.*]] = tail call i32 @llvm.smax.i32(i32 %[[COUNT]], i32 0)
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// CHECK: %[[ZEXT:.*]] = zext nneg i32 %[[NARROW]] to i64
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// CHECK: ret i64 %[[ZEXT]]
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//
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// Verify: counted_by on void* returns the count directly (count * 1 byte)
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long long test_counted_by_void(struct with_counted_by_void *s) {
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return __builtin_dynamic_object_size(s->buf, 0);
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}
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// CHECK-LABEL: define dso_local {{.*}}@test_sized_by_void(
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// CHECK: %[[SIZE:.*]] = load i32, ptr %s
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// CHECK: %[[NARROW:.*]] = tail call i32 @llvm.smax.i32(i32 %[[SIZE]], i32 0)
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// CHECK: %[[ZEXT:.*]] = zext nneg i32 %[[NARROW]] to i64
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// CHECK: ret i64 %[[ZEXT]]
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//
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// Verify: sized_by on void* returns the size directly
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long long test_sized_by_void(struct with_sized_by_void *s) {
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return __builtin_dynamic_object_size(s->buf, 0);
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}
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// CHECK-LABEL: define dso_local {{.*}}@test_counted_by_int(
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// CHECK: %[[COUNT:.*]] = load i32, ptr %s
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// CHECK: %[[SEXT:.*]] = sext i32 %[[COUNT]] to i64
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// CHECK: %[[SIZE:.*]] = shl nsw i64 %[[SEXT]], 2
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// CHECK: ret i64
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//
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// Verify: counted_by on int* returns count * sizeof(int) = count * 4
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long long test_counted_by_int(struct with_counted_by_int *s) {
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return __builtin_dynamic_object_size(s->buf, 0);
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}
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// CHECK-LABEL: define dso_local ptr @test_void_ptr_arithmetic(
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// CHECK: %[[BUF:.*]] = load ptr, ptr
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// CHECK: %[[EXT:.*]] = sext i32 %offset to i64
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// CHECK: %[[PTR:.*]] = getelementptr inbounds i8, ptr %[[BUF]], i64 %[[EXT]]
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// CHECK: ret ptr %[[PTR]]
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//
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// Verify: pointer arithmetic on void* uses i8 (byte offsets), not i32 or other sizes
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void* test_void_ptr_arithmetic(struct with_counted_by_void *s, int offset) {
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return s->buf + offset; // GNU extension: void* arithmetic
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}
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