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llvm-project/clang/test/CodeGen/object-size.cpp

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Fix a bug in __builtin_object_size cast removal Apparently there are many cast kinds that may cause implicit pointer arithmetic to happen. In light of this, the cast ignoring logic introduced in r246877 has been changed to only ignore a small set of cast kinds, and a test for this behavior has been added. Thanks to Richard for catching this before it became a bug report. :) llvm-svn: 246890
2015-09-05 06:36:18 +08:00
// RUN: %clang_cc1 -triple x86_64-apple-darwin -emit-llvm -o - %s | FileCheck %s
// C++-specific tests for __builtin_object_size
int gi;
// CHECK-LABEL: define void @_Z5test1v()
void test1() {
// Guaranteeing that our cast removal logic doesn't break more interesting
// cases.
struct A { int a; };
struct B { int b; };
struct C: public A, public B {};
C c;
// CHECK: store i32 8
gi = __builtin_object_size(&c, 0);
// CHECK: store i32 8
gi = __builtin_object_size((A*)&c, 0);
// CHECK: store i32 4
gi = __builtin_object_size((B*)&c, 0);
// CHECK: store i32 8
gi = __builtin_object_size((char*)&c, 0);
// CHECK: store i32 8
gi = __builtin_object_size((char*)(A*)&c, 0);
// CHECK: store i32 4
gi = __builtin_object_size((char*)(B*)&c, 0);
}
Make __builtin_object_size more conservative r246877 made __builtin_object_size substantially more aggressive with unknown bases if Type=1 or Type=3, which causes issues when we encounter code like this: struct Foo { int a; char str[1]; }; const char str[] = "Hello, World!"; struct Foo *f = (struct Foo *)malloc(sizeof(*f) + strlen(str)); strcpy(&f->str, str); __builtin_object_size(&f->str, 1) would hand back 1, which is technically correct given the type of Foo, but the type of Foo lies to us about how many bytes are available in this case. This patch adds support for this "writing off the end" idiom -- we now answer conservatively when we're given the address of the very last member in a struct. Differential Revision: http://reviews.llvm.org/D12169 llvm-svn: 250488
2015-10-16 09:49:01 +08:00
// CHECK-LABEL: define void @_Z5test2v()
void test2() {
struct A { char buf[16]; };
struct B : A {};
struct C { int i; B bs[1]; } *c;
// CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %{{.*}}, i1 false)
gi = __builtin_object_size(&c->bs[0], 0);
// CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %{{.*}}, i1 false)
gi = __builtin_object_size(&c->bs[0], 1);
// CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %{{.*}}, i1 true)
gi = __builtin_object_size(&c->bs[0], 2);
// CHECK: store i32 16
gi = __builtin_object_size(&c->bs[0], 3);
// CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %{{.*}}, i1 false)
gi = __builtin_object_size((A*)&c->bs[0], 0);
// CHECK: store i32 16
gi = __builtin_object_size((A*)&c->bs[0], 1);
// CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %{{.*}}, i1 true)
gi = __builtin_object_size((A*)&c->bs[0], 2);
// CHECK: store i32 16
gi = __builtin_object_size((A*)&c->bs[0], 3);
// CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %{{.*}}, i1 false)
gi = __builtin_object_size(&c->bs[0].buf[0], 0);
// CHECK: store i32 16
gi = __builtin_object_size(&c->bs[0].buf[0], 1);
// CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %{{.*}}, i1 true)
gi = __builtin_object_size(&c->bs[0].buf[0], 2);
// CHECK: store i32 16
gi = __builtin_object_size(&c->bs[0].buf[0], 3);
}