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Call out to GCC-compatible runtime functions for atomic ops that we can't use

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LLVM intrinsics for.

I have an implementation of these functions, which wants to go in a libgcc_s
equivalent in compiler-rt.  It's currently here:

http://people.freebsd.org/~theraven/atomic.c

It will be committed to compiler-rt as soon as I work out where would be a
sensible place to put it...

llvm-svn: 153666
This commit is contained in:
David Chisnall
2012-03-29 18:01:11 +00:00
parent 891ec2870d
commit db365f38ea
2 changed files with 97 additions and 34 deletions
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95
clang/lib/CodeGen/CGExpr.cpp
View File

@@ -2798,7 +2798,6 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E, llvm::Value *Dest) {
Val1 = EmitScalarExpr(E->getVal1());
Val2 = EmitValToTemp(*this, E->getVal2());
OrderFail = EmitScalarExpr(E->getOrderFail());
(void)OrderFail; // OrderFail is unused at the moment
} else if ((E->getOp() == AtomicExpr::Add || E->getOp() == AtomicExpr::Sub) &&
MemTy->isPointerType()) {
// For pointers, we're required to do a bit of math: adding 1 to an int*
@@ -2817,50 +2816,78 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E, llvm::Value *Dest) {
if (E->getOp() != AtomicExpr::Store && !Dest)
Dest = CreateMemTemp(E->getType(), ".atomicdst");
// Use a library call. See: http://gcc.gnu.org/wiki/Atomic/GCCMM/LIbrary .
if (UseLibcall) {
// FIXME: Finalize what the libcalls are actually supposed to look like.
// See also http://gcc.gnu.org/wiki/Atomic/GCCMM/LIbrary .
return EmitUnsupportedRValue(E, "atomic library call");
}
#if 0
if (UseLibcall) {
llvm::SmallVector<QualType, 5> Params;
CallArgList Args;
// Size is always the first parameter
Args.add(RValue::get(llvm::ConstantInt::get(SizeTy, Size)),
getContext().getSizeType());
// Atomic address is always the second parameter
Args.add(RValue::get(EmitCastToVoidPtr(Ptr)),
getContext().VoidPtrTy);
const char* LibCallName;
QualType RetTy = getContext().VoidTy;
switch (E->getOp()) {
// There is only one libcall for compare an exchange, because there is no
// optimisation benefit possible from a libcall version of a weak compare
// and exchange.
// bool __atomic_compare_exchange(size_t size, void *obj, void *expected,
// void *desired, int success, int failure)
case AtomicExpr::CmpXchgWeak:
LibCallName = "__atomic_compare_exchange_generic"; break;
case AtomicExpr::CmpXchgStrong:
LibCallName = "__atomic_compare_exchange_generic"; break;
LibCallName = "__atomic_compare_exchange";
RetTy = getContext().BoolTy;
Args.add(RValue::get(EmitCastToVoidPtr(Val1)),
getContext().VoidPtrTy);
Args.add(RValue::get(EmitCastToVoidPtr(Val2)),
getContext().VoidPtrTy);
Args.add(RValue::get(Order),
getContext().IntTy);
Order = OrderFail;
break;
// void __atomic_exchange(size_t size, void *mem, void *val, void *return,
// int order)
case AtomicExpr::Xchg:
LibCallName = "__atomic_exchange";
Args.add(RValue::get(EmitCastToVoidPtr(Val1)),
getContext().VoidPtrTy);
Args.add(RValue::get(EmitCastToVoidPtr(Dest)),
getContext().VoidPtrTy);
break;
// void __atomic_store(size_t size, void *mem, void *val, int order)
case AtomicExpr::Store:
LibCallName = "__atomic_store";
Args.add(RValue::get(EmitCastToVoidPtr(Val1)),
getContext().VoidPtrTy);
break;
// void __atomic_load(size_t size, void *mem, void *return, int order)
case AtomicExpr::Load:
LibCallName = "__atomic_load";
Args.add(RValue::get(EmitCastToVoidPtr(Dest)),
getContext().VoidPtrTy);
break;
#if 0
// These are only defined for 1-16 byte integers. It is not clear what
// their semantics would be on anything else...
case AtomicExpr::Add: LibCallName = "__atomic_fetch_add_generic"; break;
case AtomicExpr::Sub: LibCallName = "__atomic_fetch_sub_generic"; break;
case AtomicExpr::And: LibCallName = "__atomic_fetch_and_generic"; break;
case AtomicExpr::Or: LibCallName = "__atomic_fetch_or_generic"; break;
case AtomicExpr::Xor: LibCallName = "__atomic_fetch_xor_generic"; break;
case AtomicExpr::Xchg: LibCallName = "__atomic_exchange_generic"; break;
case AtomicExpr::Store: LibCallName = "__atomic_store_generic"; break;
case AtomicExpr::Load: LibCallName = "__atomic_load_generic"; break;
#endif
default: return EmitUnsupportedRValue(E, "atomic library call");
}
llvm::SmallVector<QualType, 4> Params;
CallArgList Args;
QualType RetTy = getContext().VoidTy;
if (E->getOp() != AtomicExpr::Store && !E->isCmpXChg())
Args.add(RValue::get(EmitCastToVoidPtr(Dest)),
getContext().VoidPtrTy);
Args.add(RValue::get(EmitCastToVoidPtr(Ptr)),
getContext().VoidPtrTy);
if (E->getOp() != AtomicExpr::Load)
Args.add(RValue::get(EmitCastToVoidPtr(Val1)),
getContext().VoidPtrTy);
if (E->isCmpXChg()) {
Args.add(RValue::get(EmitCastToVoidPtr(Val2)),
getContext().VoidPtrTy);
RetTy = getContext().IntTy;
}
Args.add(RValue::get(llvm::ConstantInt::get(SizeTy, Size)),
getContext().getSizeType());
// order is always the last parameter
Args.add(RValue::get(Order),
getContext().IntTy);
const CGFunctionInfo &FuncInfo =
CGM.getTypes().arrangeFunctionCall(RetTy, Args, FunctionType::ExtInfo(),
/*variadic*/ false);
llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FuncInfo, false);
CGM.getTypes().arrangeFunctionCall(RetTy, Args,
FunctionType::ExtInfo(), RequiredArgs::All);
llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FuncInfo);
llvm::Constant *Func = CGM.CreateRuntimeFunction(FTy, LibCallName);
RValue Res = EmitCall(FuncInfo, Func, ReturnValueSlot(), Args);
if (E->isCmpXChg())
@@ -2869,7 +2896,7 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E, llvm::Value *Dest) {
return RValue::get(0);
return ConvertTempToRValue(*this, E->getType(), Dest);
}
#endif
llvm::Type *IPtrTy =
llvm::IntegerType::get(getLLVMContext(), Size * 8)->getPointerTo();
llvm::Value *OrigDest = Dest;

36
clang/test/CodeGen/atomic-ops.c
View File

@@ -81,3 +81,39 @@ int lock_free() {
// CHECK: ret i32 1
return __atomic_is_lock_free(sizeof(_Atomic(int)));
}
// Tests for atomic operations on big values. These should call the functions
// defined here:
// http://gcc.gnu.org/wiki/Atomic/GCCMM/LIbrary#The_Library_interface
struct foo {
int big[128];
};
_Atomic(struct foo) bigAtomic;
void structAtomicStore() {
// CHECK: @structAtomicStore
struct foo f = {0};
__atomic_store(&bigAtomic, f, 5);
// CHECK: call void @__atomic_store(i32 512, i8* bitcast (%struct.foo* @bigAtomic to i8*), i8* %3, i32 5)
}
void structAtomicLoad() {
// CHECK: @structAtomicLoad
struct foo f = __atomic_load(&bigAtomic, 5);
// CHECK: call void @__atomic_load(i32 512, i8* bitcast (%struct.foo* @bigAtomic to i8*), i8* %0, i32 5)
}
struct foo structAtomicExchange() {
// CHECK: @structAtomicExchange
struct foo f = {0};
return __atomic_exchange(&bigAtomic, f, 5);
// CHECK: call void @__atomic_exchange(i32 512, i8* bitcast (%struct.foo* @bigAtomic to i8*), i8* %3, i8* %4, i32 5)
}
int structAtomicCmpExchange() {
// CHECK: @structAtomicCmpExchange
struct foo f = {0};
struct foo g = {0};
g.big[12] = 12;
return __atomic_compare_exchange_strong(&bigAtomic, &f, g, 5, 5);
// CHECK: call zeroext i1 @__atomic_compare_exchange(i32 512, i8* bitcast (%struct.foo* @bigAtomic to i8*), i8* %4, i8* %5, i32 5, i32 5)
}