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Correct atomic libcall support for __atomic_*_fetch builtins. 

In r244063, I had caused these builtins to call the same-named library
functions, __atomic_*_fetch_SIZE. However, this was incorrect: while
those functions are in fact supported by GCC's libatomic, they're not
documented by the spec (and gcc doesn't ever call them).

Instead, you're /supposed/ to call the __atomic_fetch_* builtins and
then redo the operation inline to return the final value.

Differential Revision: http://reviews.llvm.org/D14385

llvm-svn: 252920
This commit is contained in:
James Y Knight 2015-11-12 18:37:29 +00:00
parent eed0145dd2
commit 7aefb5b623
2 changed files with 52 additions and 45 deletions
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78
clang/lib/CodeGen/CGAtomic.cpp
View File

@ -613,8 +613,8 @@ static void EmitAtomicOp(CodeGenFunction &CGF, AtomicExpr *E, Address Dest,
break;
case AtomicExpr::AO__atomic_nand_fetch:
PostOp = llvm::Instruction::And;
// Fall through.
PostOp = llvm::Instruction::And; // the NOT is special cased below
// Fall through.
case AtomicExpr::AO__atomic_fetch_nand:
Op = llvm::AtomicRMWInst::Nand;
break;
@ -853,6 +853,7 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E) {
MemTy->isPointerType() ? getContext().getIntPtrType() : MemTy;
QualType RetTy;
bool HaveRetTy = false;
llvm::Instruction::BinaryOps PostOp = (llvm::Instruction::BinaryOps)0;
switch (E->getOp()) {
case AtomicExpr::AO__c11_atomic_init:
llvm_unreachable("Already handled!");
@ -906,84 +907,71 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E) {
case AtomicExpr::AO__atomic_load_n:
LibCallName = "__atomic_load";
break;
// T __atomic_add_fetch_N(T *mem, T val, int order)
// T __atomic_fetch_add_N(T *mem, T val, int order)
case AtomicExpr::AO__atomic_add_fetch:
PostOp = llvm::Instruction::Add;
// Fall through.
case AtomicExpr::AO__c11_atomic_fetch_add:
case AtomicExpr::AO__atomic_fetch_add:
LibCallName = "__atomic_fetch_add";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
LoweredMemTy, E->getExprLoc(), sizeChars);
break;
// T __atomic_and_fetch_N(T *mem, T val, int order)
// T __atomic_fetch_and_N(T *mem, T val, int order)
case AtomicExpr::AO__atomic_and_fetch:
PostOp = llvm::Instruction::And;
// Fall through.
case AtomicExpr::AO__c11_atomic_fetch_and:
case AtomicExpr::AO__atomic_fetch_and:
LibCallName = "__atomic_fetch_and";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
MemTy, E->getExprLoc(), sizeChars);
break;
// T __atomic_or_fetch_N(T *mem, T val, int order)
// T __atomic_fetch_or_N(T *mem, T val, int order)
case AtomicExpr::AO__atomic_or_fetch:
PostOp = llvm::Instruction::Or;
// Fall through.
case AtomicExpr::AO__c11_atomic_fetch_or:
case AtomicExpr::AO__atomic_fetch_or:
LibCallName = "__atomic_fetch_or";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
MemTy, E->getExprLoc(), sizeChars);
break;
// T __atomic_sub_fetch_N(T *mem, T val, int order)
// T __atomic_fetch_sub_N(T *mem, T val, int order)
case AtomicExpr::AO__atomic_sub_fetch:
PostOp = llvm::Instruction::Sub;
// Fall through.
case AtomicExpr::AO__c11_atomic_fetch_sub:
case AtomicExpr::AO__atomic_fetch_sub:
LibCallName = "__atomic_fetch_sub";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
LoweredMemTy, E->getExprLoc(), sizeChars);
break;
// T __atomic_xor_fetch_N(T *mem, T val, int order)
// T __atomic_fetch_xor_N(T *mem, T val, int order)
case AtomicExpr::AO__atomic_xor_fetch:
PostOp = llvm::Instruction::Xor;
// Fall through.
case AtomicExpr::AO__c11_atomic_fetch_xor:
case AtomicExpr::AO__atomic_fetch_xor:
LibCallName = "__atomic_fetch_xor";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
MemTy, E->getExprLoc(), sizeChars);
break;
// T __atomic_nand_fetch_N(T *mem, T val, int order)
// T __atomic_fetch_nand_N(T *mem, T val, int order)
case AtomicExpr::AO__atomic_nand_fetch:
PostOp = llvm::Instruction::And; // the NOT is special cased below
// Fall through.
case AtomicExpr::AO__atomic_fetch_nand:
LibCallName = "__atomic_fetch_nand";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
MemTy, E->getExprLoc(), sizeChars);
break;
// T __atomic_add_fetch_N(T *mem, T val, int order)
case AtomicExpr::AO__atomic_add_fetch:
LibCallName = "__atomic_add_fetch";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
LoweredMemTy, E->getExprLoc(), sizeChars);
break;
// T __atomic_and_fetch_N(T *mem, T val, int order)
case AtomicExpr::AO__atomic_and_fetch:
LibCallName = "__atomic_and_fetch";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
MemTy, E->getExprLoc(), sizeChars);
break;
// T __atomic_or_fetch_N(T *mem, T val, int order)
case AtomicExpr::AO__atomic_or_fetch:
LibCallName = "__atomic_or_fetch";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
MemTy, E->getExprLoc(), sizeChars);
break;
// T __atomic_sub_fetch_N(T *mem, T val, int order)
case AtomicExpr::AO__atomic_sub_fetch:
LibCallName = "__atomic_sub_fetch";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
LoweredMemTy, E->getExprLoc(), sizeChars);
break;
// T __atomic_xor_fetch_N(T *mem, T val, int order)
case AtomicExpr::AO__atomic_xor_fetch:
LibCallName = "__atomic_xor_fetch";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
MemTy, E->getExprLoc(), sizeChars);
break;
// T __atomic_nand_fetch_N(T *mem, T val, int order)
case AtomicExpr::AO__atomic_nand_fetch:
LibCallName = "__atomic_nand_fetch";
AddDirectArgument(*this, Args, UseOptimizedLibcall, Val1.getPointer(),
MemTy, E->getExprLoc(), sizeChars);
break;
}
// Optimized functions have the size in their name.
@ -1007,6 +995,11 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E) {
Args.add(RValue::get(Order),
getContext().IntTy);
// PostOp is only needed for the atomic_*_fetch operations, and
// thus is only needed for and implemented in the
// UseOptimizedLibcall codepath.
assert(UseOptimizedLibcall || !PostOp);
RValue Res = emitAtomicLibcall(*this, LibCallName, RetTy, Args);
// The value is returned directly from the libcall.
if (E->isCmpXChg())
@ -1016,6 +1009,13 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E) {
// provided an out-param.
if (UseOptimizedLibcall && Res.getScalarVal()) {
llvm::Value *ResVal = Res.getScalarVal();
if (PostOp) {
llvm::Value *LoadVal1 = Args[1].RV.getScalarVal();
ResVal = Builder.CreateBinOp(PostOp, ResVal, LoadVal1);
}
if (E->getOp() == AtomicExpr::AO__atomic_nand_fetch)
ResVal = Builder.CreateNot(ResVal);
Builder.CreateStore(
ResVal,
Builder.CreateBitCast(Dest, ResVal->getType()->getPointerTo()));

19
clang/test/CodeGen/atomic-ops-libcall.c
View File

@ -74,36 +74,43 @@ int test_atomic_fetch_nand(int *p) {
int test_atomic_add_fetch(int *p) {
// CHECK: test_atomic_add_fetch
// CHECK: {{%[^ ]*}} = tail call i32 @__atomic_add_fetch_4(i8* {{%[0-9]+}}, i32 55, i32 5)
// CHECK: [[CALL:%[^ ]*]] = tail call i32 @__atomic_fetch_add_4(i8* {{%[0-9]+}}, i32 55, i32 5)
// CHECK: {{%[^ ]*}} = add i32 [[CALL]], 55
return __atomic_add_fetch(p, 55, memory_order_seq_cst);
}
int test_atomic_sub_fetch(int *p) {
// CHECK: test_atomic_sub_fetch
// CHECK: {{%[^ ]*}} = tail call i32 @__atomic_sub_fetch_4(i8* {{%[0-9]+}}, i32 55, i32 5)
// CHECK: [[CALL:%[^ ]*]] = tail call i32 @__atomic_fetch_sub_4(i8* {{%[0-9]+}}, i32 55, i32 5)
// CHECK: {{%[^ ]*}} = add i32 [[CALL]], -55
return __atomic_sub_fetch(p, 55, memory_order_seq_cst);
}
int test_atomic_and_fetch(int *p) {
// CHECK: test_atomic_and_fetch
// CHECK: {{%[^ ]*}} = tail call i32 @__atomic_and_fetch_4(i8* {{%[0-9]+}}, i32 55, i32 5)
// CHECK: [[CALL:%[^ ]*]] = tail call i32 @__atomic_fetch_and_4(i8* {{%[0-9]+}}, i32 55, i32 5)
// CHECK: {{%[^ ]*}} = and i32 [[CALL]], 55
return __atomic_and_fetch(p, 55, memory_order_seq_cst);
}
int test_atomic_or_fetch(int *p) {
// CHECK: test_atomic_or_fetch
// CHECK: {{%[^ ]*}} = tail call i32 @__atomic_or_fetch_4(i8* {{%[0-9]+}}, i32 55, i32 5)
// CHECK: [[CALL:%[^ ]*]] = tail call i32 @__atomic_fetch_or_4(i8* {{%[0-9]+}}, i32 55, i32 5)
// CHECK: {{%[^ ]*}} = or i32 [[CALL]], 55
return __atomic_or_fetch(p, 55, memory_order_seq_cst);
}
int test_atomic_xor_fetch(int *p) {
// CHECK: test_atomic_xor_fetch
// CHECK: {{%[^ ]*}} = tail call i32 @__atomic_xor_fetch_4(i8* {{%[0-9]+}}, i32 55, i32 5)
// CHECK: [[CALL:%[^ ]*]] = tail call i32 @__atomic_fetch_xor_4(i8* {{%[0-9]+}}, i32 55, i32 5)
// CHECK: {{%[^ ]*}} = xor i32 [[CALL]], 55
return __atomic_xor_fetch(p, 55, memory_order_seq_cst);
}
int test_atomic_nand_fetch(int *p) {
// CHECK: test_atomic_nand_fetch
// CHECK: {{%[^ ]*}} = tail call i32 @__atomic_nand_fetch_4(i8* {{%[0-9]+}}, i32 55, i32 5)
// CHECK: [[CALL:%[^ ]*]] = tail call i32 @__atomic_fetch_nand_4(i8* {{%[0-9]+}}, i32 55, i32 5)
// CHECK: [[OR:%[^ ]*]] = or i32 [[CALL]], -56
// CHECK: {{%[^ ]*}} = xor i32 [[OR]], 55
return __atomic_nand_fetch(p, 55, memory_order_seq_cst);
}