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clang-p2996/clang/test/CodeGenCXX/arm.cpp
Roman Lebedev 3dd5a298bf [clang] Annotating C++'s operator new with more attributes 
Summary:
Right now we annotate C++'s `operator new` with `noalias` attribute,
which very much is healthy for optimizations.

However as per [[ http://eel.is/c++draft/basic.stc.dynamic.allocation | `[basic.stc.dynamic.allocation]` ]],
there are more promises on global `operator new`, namely:
* non-`std::nothrow_t` `operator new` *never* returns `nullptr`
* If `std::align_val_t align` parameter is taken, the pointer will also be `align`-aligned
* ~~global `operator new`-returned pointer is `__STDCPP_DEFAULT_NEW_ALIGNMENT__`-aligned ~~ It's more caveated than that.

Supplying this information may not cause immediate landslide effects
on any specific benchmarks, but it for sure will be healthy for optimizer
in the sense that the IR will better reflect the guarantees provided in the source code.

The caveat is `-fno-assume-sane-operator-new`, which currently prevents emitting `noalias`
attribute, and is automatically passed by Sanitizers ([[ https://bugs.llvm.org/show_bug.cgi?id=16386 | PR16386 ]]) - should it also cover these attributes?
The problem is that the flag is back-end-specific, as seen in `test/Modules/explicit-build-flags.cpp`.
But while it is okay to add `noalias` metadata in backend, we really should be adding at least
the alignment metadata to the AST, since that allows us to perform sema checks on it.

Reviewers: erichkeane, rjmccall, jdoerfert, eugenis, rsmith

Reviewed By: rsmith

Subscribers: xbolva00, jrtc27, atanasyan, nlopes, cfe-commits

Tags: #llvm, #clang

Differential Revision: https://reviews.llvm.org/D73380
2020-02-26 01:37:17 +03:00

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// RUN: %clang_cc1 %s -triple=thumbv7-apple-ios6.0 -fno-use-cxa-atexit -target-abi apcs-gnu -emit-llvm -std=gnu++98 -o - -fexceptions | FileCheck -check-prefix=CHECK -check-prefix=CHECK98 %s
// RUN: %clang_cc1 %s -triple=thumbv7-apple-ios6.0 -fno-use-cxa-atexit -target-abi apcs-gnu -emit-llvm -std=gnu++11 -o - -fexceptions | FileCheck -check-prefix=CHECK -check-prefix=CHECK11 %s
// CHECK: @_ZZN5test74testEvE1x = internal global i32 0, align 4
// CHECK: @_ZGVZN5test74testEvE1x = internal global i32 0
// CHECK: @_ZZN5test84testEvE1x = internal global [[TEST8A:.*]] zeroinitializer, align 1
// CHECK: @_ZGVZN5test84testEvE1x = internal global i32 0
typedef typeof(sizeof(int)) size_t;
class foo {
public:
foo();
virtual ~foo();
};
class bar : public foo {
public:
bar();
};
// The global dtor needs the right calling conv with -fno-use-cxa-atexit
// rdar://7817590
bar baz;
// PR9593
// Make sure atexit(3) is used for global dtors.
// CHECK: call [[BAR:%.*]]* @_ZN3barC1Ev(
// CHECK-NEXT: call i32 @atexit(void ()* @__dtor_baz)
// CHECK-NOT: @_GLOBAL__D_a()
// CHECK-LABEL: define internal void @__dtor_baz()
// CHECK: call [[BAR]]* @_ZN3barD1Ev([[BAR]]* @baz)
// Destructors and constructors must return this.
namespace test1 {
void foo();
struct A {
A(int i) { foo(); }
~A() { foo(); }
void bar() { foo(); }
};
// CHECK-LABEL: define void @_ZN5test14testEv()
void test() {
// CHECK: [[AV:%.*]] = alloca [[A:%.*]], align 1
// CHECK: call [[A]]* @_ZN5test11AC1Ei([[A]]* [[AV]], i32 10)
// CHECK: invoke void @_ZN5test11A3barEv([[A]]* [[AV]])
// CHECK: call [[A]]* @_ZN5test11AD1Ev([[A]]* [[AV]])
// CHECK: ret void
A a = 10;
a.bar();
}
// CHECK: define linkonce_odr [[A]]* @_ZN5test11AC1Ei([[A]]* returned %this, i32 %i) unnamed_addr
// CHECK: [[THIS:%.*]] = alloca [[A]]*, align 4
// CHECK: store [[A]]* {{.*}}, [[A]]** [[THIS]]
// CHECK: [[THIS1:%.*]] = load [[A]]*, [[A]]** [[THIS]]
// CHECK: {{%.*}} = call [[A]]* @_ZN5test11AC2Ei(
// CHECK: ret [[A]]* [[THIS1]]
// CHECK: define linkonce_odr [[A]]* @_ZN5test11AD1Ev([[A]]* returned %this) unnamed_addr
// CHECK: [[THIS:%.*]] = alloca [[A]]*, align 4
// CHECK: store [[A]]* {{.*}}, [[A]]** [[THIS]]
// CHECK: [[THIS1:%.*]] = load [[A]]*, [[A]]** [[THIS]]
// CHECK: {{%.*}} = call [[A]]* @_ZN5test11AD2Ev(
// CHECK: ret [[A]]* [[THIS1]]
}
// Awkward virtual cases.
namespace test2 {
void foo();
struct A {
int x;
A(int);
virtual ~A() { foo(); }
};
struct B {
int y;
int z;
B(int);
virtual ~B() { foo(); }
};
struct C : A, virtual B {
int q;
C(int i) : A(i), B(i) { foo(); }
~C() { foo(); }
};
void test() {
C c = 10;
}
// Tests at eof
}
namespace test3 {
struct A {
int x;
~A();
};
void a() {
// CHECK-LABEL: define void @_ZN5test31aEv()
// CHECK: call noalias nonnull i8* @_Znam(i32 48)
// CHECK: store i32 4
// CHECK: store i32 10
A *x = new A[10];
}
void b(int n) {
// CHECK-LABEL: define void @_ZN5test31bEi(
// CHECK: [[N:%.*]] = load i32, i32*
// CHECK: @llvm.umul.with.overflow.i32(i32 [[N]], i32 4)
// CHECK: @llvm.uadd.with.overflow.i32(i32 {{.*}}, i32 8)
// CHECK: [[OR:%.*]] = or i1
// CHECK: [[SZ:%.*]] = select i1 [[OR]]
// CHECK: call noalias nonnull i8* @_Znam(i32 [[SZ]])
// CHECK: store i32 4
// CHECK: store i32 [[N]]
A *x = new A[n];
}
void c() {
// CHECK-LABEL: define void @_ZN5test31cEv()
// CHECK: call noalias nonnull i8* @_Znam(i32 808)
// CHECK: store i32 4
// CHECK: store i32 200
A (*x)[20] = new A[10][20];
}
void d(int n) {
// CHECK-LABEL: define void @_ZN5test31dEi(
// CHECK: [[N:%.*]] = load i32, i32*
// CHECK: @llvm.umul.with.overflow.i32(i32 [[N]], i32 80)
// CHECK: [[NE:%.*]] = mul i32 [[N]], 20
// CHECK: @llvm.uadd.with.overflow.i32(i32 {{.*}}, i32 8)
// CHECK: [[SZ:%.*]] = select
// CHECK: call noalias nonnull i8* @_Znam(i32 [[SZ]])
// CHECK: store i32 4
// CHECK: store i32 [[NE]]
A (*x)[20] = new A[n][20];
}
void e(A *x) {
// CHECK-LABEL: define void @_ZN5test31eEPNS_1AE(
// CHECK: icmp eq {{.*}}, null
// CHECK: getelementptr {{.*}}, i32 -8
// CHECK: getelementptr {{.*}}, i32 4
// CHECK: bitcast {{.*}} to i32*
// CHECK: load
// CHECK98: invoke {{.*}} @_ZN5test31AD1Ev
// CHECK11: call {{.*}} @_ZN5test31AD1Ev
// CHECK: call void @_ZdaPv
delete [] x;
}
void f(A (*x)[20]) {
// CHECK-LABEL: define void @_ZN5test31fEPA20_NS_1AE(
// CHECK: icmp eq {{.*}}, null
// CHECK: getelementptr {{.*}}, i32 -8
// CHECK: getelementptr {{.*}}, i32 4
// CHECK: bitcast {{.*}} to i32*
// CHECK: load
// CHECK98: invoke {{.*}} @_ZN5test31AD1Ev
// CHECK11: call {{.*}} @_ZN5test31AD1Ev
// CHECK: call void @_ZdaPv
delete [] x;
}
}
namespace test4 {
struct A {
int x;
void operator delete[](void *, size_t sz);
};
void a() {
// CHECK-LABEL: define void @_ZN5test41aEv()
// CHECK: call noalias nonnull i8* @_Znam(i32 48)
// CHECK: store i32 4
// CHECK: store i32 10
A *x = new A[10];
}
void b(int n) {
// CHECK-LABEL: define void @_ZN5test41bEi(
// CHECK: [[N:%.*]] = load i32, i32*
// CHECK: @llvm.umul.with.overflow.i32(i32 [[N]], i32 4)
// CHECK: @llvm.uadd.with.overflow.i32(i32 {{.*}}, i32 8)
// CHECK: [[SZ:%.*]] = select
// CHECK: call noalias nonnull i8* @_Znam(i32 [[SZ]])
// CHECK: store i32 4
// CHECK: store i32 [[N]]
A *x = new A[n];
}
void c() {
// CHECK-LABEL: define void @_ZN5test41cEv()
// CHECK: call noalias nonnull i8* @_Znam(i32 808)
// CHECK: store i32 4
// CHECK: store i32 200
A (*x)[20] = new A[10][20];
}
void d(int n) {
// CHECK-LABEL: define void @_ZN5test41dEi(
// CHECK: [[N:%.*]] = load i32, i32*
// CHECK: @llvm.umul.with.overflow.i32(i32 [[N]], i32 80)
// CHECK: [[NE:%.*]] = mul i32 [[N]], 20
// CHECK: @llvm.uadd.with.overflow.i32(i32 {{.*}}, i32 8)
// CHECK: [[SZ:%.*]] = select
// CHECK: call noalias nonnull i8* @_Znam(i32 [[SZ]])
// CHECK: store i32 4
// CHECK: store i32 [[NE]]
A (*x)[20] = new A[n][20];
}
void e(A *x) {
// CHECK-LABEL: define void @_ZN5test41eEPNS_1AE(
// CHECK: [[ALLOC:%.*]] = getelementptr inbounds {{.*}}, i32 -8
// CHECK: getelementptr inbounds {{.*}}, i32 4
// CHECK: bitcast
// CHECK: [[T0:%.*]] = load i32, i32*
// CHECK: [[T1:%.*]] = mul i32 4, [[T0]]
// CHECK: [[T2:%.*]] = add i32 [[T1]], 8
// CHECK: call void @_ZN5test41AdaEPvm(i8* [[ALLOC]], i32 [[T2]])
delete [] x;
}
void f(A (*x)[20]) {
// CHECK-LABEL: define void @_ZN5test41fEPA20_NS_1AE(
// CHECK: [[ALLOC:%.*]] = getelementptr inbounds {{.*}}, i32 -8
// CHECK: getelementptr inbounds {{.*}}, i32 4
// CHECK: bitcast
// CHECK: [[T0:%.*]] = load i32, i32*
// CHECK: [[T1:%.*]] = mul i32 4, [[T0]]
// CHECK: [[T2:%.*]] = add i32 [[T1]], 8
// CHECK: call void @_ZN5test41AdaEPvm(i8* [[ALLOC]], i32 [[T2]])
delete [] x;
}
}
// <rdar://problem/8386802>: don't crash
namespace test5 {
struct A {
~A();
};
// CHECK-LABEL: define void @_ZN5test54testEPNS_1AE
void test(A *a) {
// CHECK: [[PTR:%.*]] = alloca [[A:%.*]]*, align 4
// CHECK-NEXT: store [[A]]* {{.*}}, [[A]]** [[PTR]], align 4
// CHECK-NEXT: [[TMP:%.*]] = load [[A]]*, [[A]]** [[PTR]], align 4
// CHECK-NEXT: call [[A]]* @_ZN5test51AD1Ev([[A]]* [[TMP]])
// CHECK-NEXT: ret void
a->~A();
}
}
namespace test6 {
struct A {
virtual ~A();
};
// CHECK-LABEL: define void @_ZN5test64testEPNS_1AE
void test(A *a) {
// CHECK: [[AVAR:%.*]] = alloca [[A:%.*]]*, align 4
// CHECK-NEXT: store [[A]]* {{.*}}, [[A]]** [[AVAR]], align 4
// CHECK-NEXT: [[V:%.*]] = load [[A]]*, [[A]]** [[AVAR]], align 4
// CHECK-NEXT: [[ISNULL:%.*]] = icmp eq [[A]]* [[V]], null
// CHECK-NEXT: br i1 [[ISNULL]]
// CHECK: [[T0:%.*]] = bitcast [[A]]* [[V]] to void ([[A]]*)***
// CHECK-NEXT: [[T1:%.*]] = load void ([[A]]*)**, void ([[A]]*)*** [[T0]]
// CHECK-NEXT: [[T2:%.*]] = getelementptr inbounds void ([[A]]*)*, void ([[A]]*)** [[T1]], i64 1
// CHECK-NEXT: [[T3:%.*]] = load void ([[A]]*)*, void ([[A]]*)** [[T2]]
// CHECK-NEXT: call void [[T3]]([[A]]* [[V]])
// CHECK-NEXT: br label
// CHECK: ret void
delete a;
}
}
namespace test7 {
int foo();
// Static and guard tested at top of file
// CHECK-LABEL: define void @_ZN5test74testEv() {{.*}} personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*)
void test() {
// CHECK: [[T0:%.*]] = load atomic i8, i8* bitcast (i32* @_ZGVZN5test74testEvE1x to i8*) acquire, align 4
// CHECK-NEXT: [[T1:%.*]] = and i8 [[T0]], 1
// CHECK-NEXT: [[T2:%.*]] = icmp eq i8 [[T1]], 0
// CHECK-NEXT: br i1 [[T2]]
// -> fallthrough, end
// CHECK: [[T3:%.*]] = call i32 @__cxa_guard_acquire(i32* @_ZGVZN5test74testEvE1x)
// CHECK-NEXT: [[T4:%.*]] = icmp ne i32 [[T3]], 0
// CHECK-NEXT: br i1 [[T4]]
// -> fallthrough, end
// CHECK: [[INIT:%.*]] = invoke i32 @_ZN5test73fooEv()
// CHECK: store i32 [[INIT]], i32* @_ZZN5test74testEvE1x, align 4
// CHECK-NEXT: call void @__cxa_guard_release(i32* @_ZGVZN5test74testEvE1x)
// CHECK-NEXT: br label
// -> end
// end:
// CHECK: ret void
static int x = foo();
// CHECK: landingpad { i8*, i32 }
// CHECK-NEXT: cleanup
// CHECK: call void @__cxa_guard_abort(i32* @_ZGVZN5test74testEvE1x)
// CHECK: resume { i8*, i32 }
}
}
namespace test8 {
struct A {
A();
~A();
};
// Static and guard tested at top of file
// CHECK-LABEL: define void @_ZN5test84testEv() {{.*}} personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*)
void test() {
// CHECK: [[T0:%.*]] = load atomic i8, i8* bitcast (i32* @_ZGVZN5test84testEvE1x to i8*) acquire, align 4
// CHECK-NEXT: [[T1:%.*]] = and i8 [[T0]], 1
// CHECK-NEXT: [[T2:%.*]] = icmp eq i8 [[T1]], 0
// CHECK-NEXT: br i1 [[T2]]
// -> fallthrough, end
// CHECK: [[T3:%.*]] = call i32 @__cxa_guard_acquire(i32* @_ZGVZN5test84testEvE1x)
// CHECK-NEXT: [[T4:%.*]] = icmp ne i32 [[T3]], 0
// CHECK-NEXT: br i1 [[T4]]
// -> fallthrough, end
// CHECK: [[INIT:%.*]] = invoke [[TEST8A]]* @_ZN5test81AC1Ev([[TEST8A]]* @_ZZN5test84testEvE1x)
// FIXME: Here we register a global destructor that
// unconditionally calls the destructor. That's what we've always
// done for -fno-use-cxa-atexit here, but that's really not
// semantically correct at all.
// CHECK: call void @__cxa_guard_release(i32* @_ZGVZN5test84testEvE1x)
// CHECK-NEXT: br label
// -> end
// end:
// CHECK: ret void
static A x;
// CHECK: landingpad { i8*, i32 }
// CHECK-NEXT: cleanup
// CHECK: call void @__cxa_guard_abort(i32* @_ZGVZN5test84testEvE1x)
// CHECK: resume { i8*, i32 }
}
}
// rdar://12836470
// Use a larger-than-mandated array cookie when allocating an
// array whose type is overaligned.
namespace test9 {
class __attribute__((aligned(16))) A {
float data[4];
public:
A();
~A();
};
A *testNew(unsigned n) {
return new A[n];
}
// CHECK: define [[TEST9:%.*]]* @_ZN5test97testNewEj(i32
// CHECK: [[N_VAR:%.*]] = alloca i32, align 4
// CHECK: [[N:%.*]] = load i32, i32* [[N_VAR]], align 4
// CHECK-NEXT: [[T0:%.*]] = call { i32, i1 } @llvm.umul.with.overflow.i32(i32 [[N]], i32 16)
// CHECK-NEXT: [[O0:%.*]] = extractvalue { i32, i1 } [[T0]], 1
// CHECK-NEXT: [[T1:%.*]] = extractvalue { i32, i1 } [[T0]], 0
// CHECK-NEXT: [[T2:%.*]] = call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 [[T1]], i32 16)
// CHECK-NEXT: [[O1:%.*]] = extractvalue { i32, i1 } [[T2]], 1
// CHECK-NEXT: [[OVERFLOW:%.*]] = or i1 [[O0]], [[O1]]
// CHECK-NEXT: [[T3:%.*]] = extractvalue { i32, i1 } [[T2]], 0
// CHECK-NEXT: [[T4:%.*]] = select i1 [[OVERFLOW]], i32 -1, i32 [[T3]]
// CHECK-NEXT: [[ALLOC:%.*]] = call noalias nonnull i8* @_Znam(i32 [[T4]])
// CHECK-NEXT: [[T0:%.*]] = bitcast i8* [[ALLOC]] to i32*
// CHECK-NEXT: store i32 16, i32* [[T0]]
// CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds i32, i32* [[T0]], i32 1
// CHECK-NEXT: store i32 [[N]], i32* [[T1]]
// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds i8, i8* [[ALLOC]], i32 16
// CHECK-NEXT: bitcast i8* [[T0]] to [[TEST9]]*
// Array allocation follows.
void testDelete(A *array) {
delete[] array;
}
// CHECK-LABEL: define void @_ZN5test910testDeleteEPNS_1AE(
// CHECK: [[BEGIN:%.*]] = load [[TEST9]]*, [[TEST9]]**
// CHECK-NEXT: [[T0:%.*]] = icmp eq [[TEST9]]* [[BEGIN]], null
// CHECK-NEXT: br i1 [[T0]],
// CHECK: [[T0:%.*]] = bitcast [[TEST9]]* [[BEGIN]] to i8*
// CHECK-NEXT: [[ALLOC:%.*]] = getelementptr inbounds i8, i8* [[T0]], i32 -16
// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds i8, i8* [[ALLOC]], i32 4
// CHECK-NEXT: [[T1:%.*]] = bitcast i8* [[T0]] to i32*
// CHECK-NEXT: [[N:%.*]] = load i32, i32* [[T1]]
// CHECK-NEXT: [[END:%.*]] = getelementptr inbounds [[TEST9]], [[TEST9]]* [[BEGIN]], i32 [[N]]
// CHECK-NEXT: [[T0:%.*]] = icmp eq [[TEST9]]* [[BEGIN]], [[END]]
// CHECK-NEXT: br i1 [[T0]],
// Array deallocation follows.
}
// CHECK: define linkonce_odr [[C:%.*]]* @_ZTv0_n12_N5test21CD1Ev(
// CHECK: call [[C]]* @_ZN5test21CD1Ev(
// CHECK: ret [[C]]* undef
// CHECK-LABEL: define linkonce_odr void @_ZTv0_n12_N5test21CD0Ev(
// CHECK: call void @_ZN5test21CD0Ev(
// CHECK: ret void
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