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[CGAtomic] Mark atomic libcall functions `nounwind` 

These functions won't ever unwind. This is useful for MemorySanitizer
as it simplifies handling __atomic_load in particular.

Differential Revision: https://reviews.llvm.org/D85573
This commit is contained in:
Gui Andrade 2020-08-14 07:34:01 +00:00
parent d795f968d9
commit 909a851dbf
2 changed files with 15 additions and 1 deletions
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9
clang/lib/CodeGen/CGAtomic.cpp
View File

@ -307,7 +307,14 @@ static RValue emitAtomicLibcall(CodeGenFunction &CGF,
const CGFunctionInfo &fnInfo =
CGF.CGM.getTypes().arrangeBuiltinFunctionCall(resultType, args);
llvm::FunctionType *fnTy = CGF.CGM.getTypes().GetFunctionType(fnInfo);
llvm::FunctionCallee fn = CGF.CGM.CreateRuntimeFunction(fnTy, fnName);
llvm::AttrBuilder fnAttrB;
fnAttrB.addAttribute(llvm::Attribute::NoUnwind);
fnAttrB.addAttribute(llvm::Attribute::WillReturn);
llvm::AttributeList fnAttrs = llvm::AttributeList::get(
CGF.getLLVMContext(), llvm::AttributeList::FunctionIndex, fnAttrB);
llvm::FunctionCallee fn =
CGF.CGM.CreateRuntimeFunction(fnTy, fnName, fnAttrs);
auto callee = CGCallee::forDirect(fn);
return CGF.EmitCall(fnInfo, callee, ReturnValueSlot(), args);
}

7
clang/test/CodeGen/atomic_ops.c
View File

@ -26,6 +26,9 @@ void foo(int x)
}
// LIBCALL: declare void @__atomic_load(i32, i8*, i8*, i32) [[LC_ATTRS:#[0-9]+]]
// LIBCALL: declare i1 @__atomic_compare_exchange(i32, i8*, i8*, i8*, i32, i32) [[LC_ATTRS:#[0-9]+]]
extern _Atomic _Bool b;
_Bool bar() {
@ -53,6 +56,8 @@ void baz(int y) {
x += y;
}
// LIBCALL: declare void @__atomic_store(i32, i8*, i8*, i32) [[LC_ATTRS:#[0-9]+]]
_Atomic(int) compound_add(_Atomic(int) in) {
// CHECK-LABEL: @compound_add
// CHECK: [[OLD:%.*]] = atomicrmw add i32* {{.*}}, i32 5 seq_cst
@ -107,3 +112,5 @@ _Atomic(int) compound_mul(_Atomic(int) in) {
return (in *= 5);
}
// LIBCALL: [[LC_ATTRS]] = { nounwind willreturn }