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Added atomic_fetch_min, max, umin, umax intrinsics to clang. 

These intrinsics work exactly as all other atomic_fetch_* intrinsics and allow to create *atomicrmw* with ordering.
Updated the clang-extensions document.

Differential Revision: https://reviews.llvm.org/D46386



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@332193 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Elena Demikhovsky 2018-05-13 07:45:58 +00:00
parent 04289bb9d4
commit 1064f0a9da
8 changed files with 84 additions and 3 deletions
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27
docs/LanguageExtensions.rst
View File

@ -1975,6 +1975,32 @@ is disallowed in general).
Support for constant expression evaluation for the above builtins be detected
with ``__has_feature(cxx_constexpr_string_builtins)``.
Atomic Min/Max builtins with memory ordering
--------------------------------------------
There are two atomic builtins with min/max in-memory comparison and swap.
The syntax and semantics are similar to GCC-compatible __atomic_* builtins.
* ``__atomic_fetch_min``
* ``__atomic_fetch_max``
The builtins work with signed and unsigned integers and require to specify memory ordering.
The return value is the original value that was stored in memory before comparison.
Example:
.. code-block:: c
unsigned int val = __atomic_fetch_min(unsigned int *pi, unsigned int ui, __ATOMIC_RELAXED);
The third argument is one of the memory ordering specifiers ``__ATOMIC_RELAXED``,
``__ATOMIC_CONSUME``, ``__ATOMIC_ACQUIRE``, ``__ATOMIC_RELEASE``,
``__ATOMIC_ACQ_REL``, or ``__ATOMIC_SEQ_CST`` following C++11 memory model semantics.
In terms or aquire-release ordering barriers these two operations are always
considered as operations with *load-store* semantics, even when the original value
is not actually modified after comparison.
.. _langext-__c11_atomic:
__c11_atomic builtins
@ -2734,4 +2760,3 @@ Specifying Linker Options on ELF Targets
The ``#pragma comment(lib, ...)`` directive is supported on all ELF targets.
The second parameter is the library name (without the traditional Unix prefix of
``lib``). This allows you to provide an implicit link of dependent libraries.

4
include/clang/Basic/Builtins.def
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@ -721,6 +721,10 @@ ATOMIC_BUILTIN(__opencl_atomic_fetch_xor, "v.", "t")
ATOMIC_BUILTIN(__opencl_atomic_fetch_min, "v.", "t")
ATOMIC_BUILTIN(__opencl_atomic_fetch_max, "v.", "t")
// GCC does not support these, they are a Clang extension.
ATOMIC_BUILTIN(__atomic_fetch_min, "iiD*i.", "t")
ATOMIC_BUILTIN(__atomic_fetch_max, "v.", "t")
#undef ATOMIC_BUILTIN
// Non-overloaded atomic builtins.

2
include/clang/Basic/DiagnosticSemaKinds.td
View File

@ -7127,6 +7127,8 @@ def err_atomic_op_needs_trivial_copy : Error<
def err_atomic_op_needs_atomic_int_or_ptr : Error<
"address argument to atomic operation must be a pointer to %select{|atomic }0"
"integer or pointer (%1 invalid)">;
def err_atomic_op_needs_int32_or_ptr : Error<
"address argument to atomic operation must be a pointer to signed or unsigned 32-bit integer">;
def err_atomic_op_bitwise_needs_atomic_int : Error<
"address argument to bitwise atomic operation must be a pointer to "
"%select{|atomic }0integer (%1 invalid)">;

2
lib/AST/Expr.cpp
View File

@ -4052,6 +4052,8 @@ unsigned AtomicExpr::getNumSubExprs(AtomicOp Op) {
case AO__atomic_or_fetch:
case AO__atomic_xor_fetch:
case AO__atomic_nand_fetch:
case AO__atomic_fetch_min:
case AO__atomic_fetch_max:
return 3;
case AO__opencl_atomic_store:

8
lib/CodeGen/CGAtomic.cpp
View File

@ -591,11 +591,13 @@ static void EmitAtomicOp(CodeGenFunction &CGF, AtomicExpr *E, Address Dest,
break;
case AtomicExpr::AO__opencl_atomic_fetch_min:
case AtomicExpr::AO__atomic_fetch_min:
Op = E->getValueType()->isSignedIntegerType() ? llvm::AtomicRMWInst::Min
: llvm::AtomicRMWInst::UMin;
break;
case AtomicExpr::AO__opencl_atomic_fetch_max:
case AtomicExpr::AO__atomic_fetch_max:
Op = E->getValueType()->isSignedIntegerType() ? llvm::AtomicRMWInst::Max
: llvm::AtomicRMWInst::UMax;
break;
@ -859,6 +861,8 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E) {
case AtomicExpr::AO__atomic_or_fetch:
case AtomicExpr::AO__atomic_xor_fetch:
case AtomicExpr::AO__atomic_nand_fetch:
case AtomicExpr::AO__atomic_fetch_min:
case AtomicExpr::AO__atomic_fetch_max:
Val1 = EmitValToTemp(*this, E->getVal1());
break;
}
@ -913,6 +917,8 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E) {
case AtomicExpr::AO__atomic_or_fetch:
case AtomicExpr::AO__atomic_sub_fetch:
case AtomicExpr::AO__atomic_xor_fetch:
case AtomicExpr::AO__atomic_fetch_min:
case AtomicExpr::AO__atomic_fetch_max:
// For these, only library calls for certain sizes exist.
UseOptimizedLibcall = true;
break;
@ -1095,6 +1101,7 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E) {
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
MemTy, E->getExprLoc(), sizeChars);
break;
case AtomicExpr::AO__atomic_fetch_min:
case AtomicExpr::AO__opencl_atomic_fetch_min:
LibCallName = E->getValueType()->isSignedIntegerType()
? "__atomic_fetch_min"
@ -1102,6 +1109,7 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E) {
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
LoweredMemTy, E->getExprLoc(), sizeChars);
break;
case AtomicExpr::AO__atomic_fetch_max:
case AtomicExpr::AO__opencl_atomic_fetch_max:
LibCallName = E->getValueType()->isSignedIntegerType()
? "__atomic_fetch_max"

20
lib/Sema/SemaChecking.cpp
View File

@ -3260,6 +3260,7 @@ ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult,
Op == AtomicExpr::AO__atomic_exchange_n ||
Op == AtomicExpr::AO__atomic_compare_exchange_n;
bool IsAddSub = false;
bool IsMinMax = false;
switch (Op) {
case AtomicExpr::AO__c11_atomic_init:
@ -3313,6 +3314,12 @@ ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult,
Form = Arithmetic;
break;
case AtomicExpr::AO__atomic_fetch_min:
case AtomicExpr::AO__atomic_fetch_max:
IsMinMax = true;
Form = Arithmetic;
break;
case AtomicExpr::AO__c11_atomic_exchange:
case AtomicExpr::AO__opencl_atomic_exchange:
case AtomicExpr::AO__atomic_exchange_n:
@ -3395,12 +3402,21 @@ ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult,
// For an arithmetic operation, the implied arithmetic must be well-formed.
if (Form == Arithmetic) {
// gcc does not enforce these rules for GNU atomics, but we do so for sanity.
if (IsAddSub && !ValType->isIntegerType() && !ValType->isPointerType()) {
if (IsAddSub && !ValType->isIntegerType()
&& !ValType->isPointerType()) {
Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
<< IsC11 << Ptr->getType() << Ptr->getSourceRange();
return ExprError();
}
if (!IsAddSub && !ValType->isIntegerType()) {
if (IsMinMax) {
const BuiltinType *BT = ValType->getAs<BuiltinType>();
if (!BT || (BT->getKind() != BuiltinType::Int &&
BT->getKind() != BuiltinType::UInt)) {
Diag(DRE->getLocStart(), diag::err_atomic_op_needs_int32_or_ptr);
return ExprError();
}
}
if (!IsAddSub && !IsMinMax && !ValType->isIntegerType()) {
Diag(DRE->getLocStart(), diag::err_atomic_op_bitwise_needs_atomic_int)
<< IsC11 << Ptr->getType() << Ptr->getSourceRange();
return ExprError();

7
test/CodeGen/Atomics.c
View File

@ -291,3 +291,10 @@ void test_lock (void)
__sync_lock_release (&sll); // CHECK: store atomic {{.*}} release, align 8
__sync_lock_release (&ull); // CHECK: store atomic {{.*}} release, align 8
}
void test_atomic(void) {
ui = __atomic_fetch_min(&ui, 5, __ATOMIC_RELAXED); // CHECK: atomicrmw umin {{.*}} monotonic
si = __atomic_fetch_min(&si, 5, __ATOMIC_SEQ_CST); // CHECK: atomicrmw min {{.*}} seq_cst
ui = __atomic_fetch_max(&ui, 5, __ATOMIC_ACQUIRE); // CHECK: atomicrmw umax {{.*}} acquire
si = __atomic_fetch_max(&si, 5, __ATOMIC_RELEASE); // CHECK: atomicrmw max {{.*}} release
}

17
test/Sema/atomic-ops.c
View File

@ -173,6 +173,9 @@ void f(_Atomic(int) *i, const _Atomic(int) *ci,
__atomic_fetch_sub(P, 3, memory_order_seq_cst);
__atomic_fetch_sub(D, 3, memory_order_seq_cst); // expected-error {{must be a pointer to integer or pointer}}
__atomic_fetch_sub(s1, 3, memory_order_seq_cst); // expected-error {{must be a pointer to integer or pointer}}
__atomic_fetch_min(D, 3, memory_order_seq_cst); // expected-error {{must be a pointer to signed or unsigned 32-bit integer}}
__atomic_fetch_max(P, 3, memory_order_seq_cst); // expected-error {{must be a pointer to signed or unsigned 32-bit integer}}
__atomic_fetch_max(p, 3); // expected-error {{too few arguments to function call, expected 3, have 2}}
__c11_atomic_fetch_and(i, 1, memory_order_seq_cst);
__c11_atomic_fetch_and(p, 1, memory_order_seq_cst); // expected-error {{must be a pointer to atomic integer}}
@ -456,6 +459,20 @@ void memory_checks(_Atomic(int) *Ap, int *p, int val) {
(void)__atomic_fetch_nand(p, val, memory_order_acq_rel);
(void)__atomic_fetch_nand(p, val, memory_order_seq_cst);
(void)__atomic_fetch_min(p, val, memory_order_relaxed);
(void)__atomic_fetch_min(p, val, memory_order_acquire);
(void)__atomic_fetch_min(p, val, memory_order_consume);
(void)__atomic_fetch_min(p, val, memory_order_release);
(void)__atomic_fetch_min(p, val, memory_order_acq_rel);
(void)__atomic_fetch_min(p, val, memory_order_seq_cst);
(void)__atomic_fetch_max(p, val, memory_order_relaxed);
(void)__atomic_fetch_max(p, val, memory_order_acquire);
(void)__atomic_fetch_max(p, val, memory_order_consume);
(void)__atomic_fetch_max(p, val, memory_order_release);
(void)__atomic_fetch_max(p, val, memory_order_acq_rel);
(void)__atomic_fetch_max(p, val, memory_order_seq_cst);
(void)__atomic_and_fetch(p, val, memory_order_relaxed);
(void)__atomic_and_fetch(p, val, memory_order_acquire);
(void)__atomic_and_fetch(p, val, memory_order_consume);