llvm-project/clang/lib/CodeGen/TargetInfo.cpp
Pierre van Houtryve b79ba02479
[AMDGPU][GFX12.5] Reimplement monitor load as an atomic operation (#177343)
Load monitor operations make more sense as atomic operations, as
non-atomic operations cannot be used for inter-thread communication w/o
additional synchronization.
The previous built-in made it work because one could just override the
CPol bits, but that bypasses the memory model and forces the user to learn
about ISA bits encoding.

Making load monitor an atomic operation has a couple of advantages.
First, the memory model foundation for it is stronger. We just lean on the
existing rules for atomic operations. Second, the CPol bits are abstracted away
from the user, which avoids leaking ISA details into the API.

This patch also adds supporting memory model and intrinsics
documentation to AMDGPUUsage.

Solves SWDEV-516398.
2026-02-09 09:57:27 +01:00

301 lines
11 KiB
C++

//===---- TargetInfo.cpp - Encapsulate target details -----------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// These classes wrap the information about a call or function
// definition used to handle ABI compliancy.
//
//===----------------------------------------------------------------------===//
#include "TargetInfo.h"
#include "ABIInfo.h"
#include "ABIInfoImpl.h"
#include "CodeGenFunction.h"
#include "clang/Basic/CodeGenOptions.h"
#include "clang/CodeGen/CGFunctionInfo.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/raw_ostream.h"
using namespace clang;
using namespace CodeGen;
LLVM_DUMP_METHOD void ABIArgInfo::dump() const {
raw_ostream &OS = llvm::errs();
OS << "(ABIArgInfo Kind=";
switch (TheKind) {
case Direct:
OS << "Direct Type=";
if (llvm::Type *Ty = getCoerceToType())
Ty->print(OS);
else
OS << "null";
break;
case Extend:
OS << "Extend";
break;
case Ignore:
OS << "Ignore";
break;
case InAlloca:
OS << "InAlloca Offset=" << getInAllocaFieldIndex();
break;
case Indirect:
OS << "Indirect Align=" << getIndirectAlign().getQuantity()
<< " ByVal=" << getIndirectByVal()
<< " Realign=" << getIndirectRealign();
break;
case IndirectAliased:
OS << "Indirect Align=" << getIndirectAlign().getQuantity()
<< " AadrSpace=" << getIndirectAddrSpace()
<< " Realign=" << getIndirectRealign();
break;
case Expand:
OS << "Expand";
break;
case CoerceAndExpand:
OS << "CoerceAndExpand Type=";
getCoerceAndExpandType()->print(OS);
break;
case TargetSpecific:
OS << "TargetSpecific Type=";
if (llvm::Type *Ty = getCoerceToType())
Ty->print(OS);
else
OS << "null";
break;
}
OS << ")\n";
}
TargetCodeGenInfo::TargetCodeGenInfo(std::unique_ptr<ABIInfo> Info)
: Info(std::move(Info)) {}
TargetCodeGenInfo::~TargetCodeGenInfo() = default;
// If someone can figure out a general rule for this, that would be great.
// It's probably just doomed to be platform-dependent, though.
unsigned TargetCodeGenInfo::getSizeOfUnwindException() const {
if (getABIInfo().getCodeGenOpts().hasSEHExceptions())
return getABIInfo().getDataLayout().getPointerSizeInBits() > 32 ? 64 : 48;
// Verified for:
// x86-64 FreeBSD, Linux, Darwin
// x86-32 FreeBSD, Linux, Darwin
// PowerPC Linux
// ARM Darwin (*not* EABI)
// AArch64 Linux
return 32;
}
bool TargetCodeGenInfo::isNoProtoCallVariadic(const CallArgList &args,
const FunctionNoProtoType *fnType) const {
// The following conventions are known to require this to be false:
// x86_stdcall
// MIPS
// For everything else, we just prefer false unless we opt out.
return false;
}
void
TargetCodeGenInfo::getDependentLibraryOption(llvm::StringRef Lib,
llvm::SmallString<24> &Opt) const {
// This assumes the user is passing a library name like "rt" instead of a
// filename like "librt.a/so", and that they don't care whether it's static or
// dynamic.
Opt = "-l";
Opt += Lib;
}
unsigned TargetCodeGenInfo::getDeviceKernelCallingConv() const {
if (getABIInfo().getContext().getLangOpts().OpenCL) {
// Device kernels are called via an explicit runtime API with arguments,
// such as set with clSetKernelArg() for OpenCL, not as normal
// sub-functions. Return SPIR_KERNEL by default as the kernel calling
// convention to ensure the fingerprint is fixed such way that each kernel
// argument gets one matching argument in the produced kernel function
// argument list to enable feasible implementation of clSetKernelArg() with
// aggregates etc. In case we would use the default C calling conv here,
// clSetKernelArg() might break depending on the target-specific
// conventions; different targets might split structs passed as values
// to multiple function arguments etc.
return llvm::CallingConv::SPIR_KERNEL;
}
llvm_unreachable("Unknown kernel calling convention");
}
void TargetCodeGenInfo::setOCLKernelStubCallingConvention(
const FunctionType *&FT) const {
FT = getABIInfo().getContext().adjustFunctionType(
FT, FT->getExtInfo().withCallingConv(CC_C));
}
llvm::Constant *TargetCodeGenInfo::getNullPointer(const CodeGen::CodeGenModule &CGM,
llvm::PointerType *T, QualType QT) const {
return llvm::ConstantPointerNull::get(T);
}
LangAS TargetCodeGenInfo::getGlobalVarAddressSpace(CodeGenModule &CGM,
const VarDecl *D) const {
assert(!CGM.getLangOpts().OpenCL &&
!(CGM.getLangOpts().CUDA && CGM.getLangOpts().CUDAIsDevice) &&
"Address space agnostic languages only");
return D ? D->getType().getAddressSpace() : LangAS::Default;
}
StringRef
TargetCodeGenInfo::getLLVMSyncScopeStr(const LangOptions &LangOpts,
SyncScope Scope,
llvm::AtomicOrdering Ordering) const {
return ""; /* default sync scope */
}
llvm::SyncScope::ID
TargetCodeGenInfo::getLLVMSyncScopeID(const LangOptions &LangOpts,
SyncScope Scope,
llvm::AtomicOrdering Ordering,
llvm::LLVMContext &Ctx) const {
return Ctx.getOrInsertSyncScopeID(
getLLVMSyncScopeStr(LangOpts, Scope, Ordering));
}
void TargetCodeGenInfo::addStackProbeTargetAttributes(
const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &CGM) const {
if (llvm::Function *Fn = dyn_cast_or_null<llvm::Function>(GV)) {
if (CGM.getCodeGenOpts().StackProbeSize != 4096)
Fn->addFnAttr("stack-probe-size",
llvm::utostr(CGM.getCodeGenOpts().StackProbeSize));
if (CGM.getCodeGenOpts().NoStackArgProbe)
Fn->addFnAttr("no-stack-arg-probe");
}
}
/// Create an OpenCL kernel for an enqueued block.
///
/// The kernel has the same function type as the block invoke function. Its
/// name is the name of the block invoke function postfixed with "_kernel".
/// It simply calls the block invoke function then returns.
llvm::Value *TargetCodeGenInfo::createEnqueuedBlockKernel(
CodeGenFunction &CGF, llvm::Function *Invoke, llvm::Type *BlockTy) const {
auto *InvokeFT = Invoke->getFunctionType();
auto &C = CGF.getLLVMContext();
std::string Name = Invoke->getName().str() + "_kernel";
auto *FT = llvm::FunctionType::get(llvm::Type::getVoidTy(C),
InvokeFT->params(), false);
auto *F = llvm::Function::Create(FT, llvm::GlobalValue::ExternalLinkage, Name,
&CGF.CGM.getModule());
llvm::CallingConv::ID KernelCC =
CGF.getTypes().ClangCallConvToLLVMCallConv(CallingConv::CC_DeviceKernel);
F->setCallingConv(KernelCC);
llvm::AttrBuilder KernelAttrs(C);
// FIXME: This is missing setTargetAttributes
CGF.CGM.addDefaultFunctionDefinitionAttributes(KernelAttrs);
F->addFnAttrs(KernelAttrs);
auto IP = CGF.Builder.saveIP();
auto *BB = llvm::BasicBlock::Create(C, "entry", F);
auto &Builder = CGF.Builder;
Builder.SetInsertPoint(BB);
llvm::SmallVector<llvm::Value *, 2> Args(llvm::make_pointer_range(F->args()));
llvm::CallInst *Call = Builder.CreateCall(Invoke, Args);
Call->setCallingConv(Invoke->getCallingConv());
Builder.CreateRetVoid();
Builder.restoreIP(IP);
return F;
}
void TargetCodeGenInfo::setBranchProtectionFnAttributes(
const TargetInfo::BranchProtectionInfo &BPI, llvm::Function &F) {
// Called on already created and initialized function where attributes already
// set from command line attributes but some might need to be removed as the
// actual BPI is different.
if (BPI.SignReturnAddr != LangOptions::SignReturnAddressScopeKind::None) {
F.addFnAttr("sign-return-address", BPI.getSignReturnAddrStr());
F.addFnAttr("sign-return-address-key", BPI.getSignKeyStr());
} else {
if (F.hasFnAttribute("sign-return-address"))
F.removeFnAttr("sign-return-address");
if (F.hasFnAttribute("sign-return-address-key"))
F.removeFnAttr("sign-return-address-key");
}
auto AddRemoveAttributeAsSet = [&](bool Set, const StringRef &ModAttr) {
if (Set)
F.addFnAttr(ModAttr);
else if (F.hasFnAttribute(ModAttr))
F.removeFnAttr(ModAttr);
};
AddRemoveAttributeAsSet(BPI.BranchTargetEnforcement,
"branch-target-enforcement");
AddRemoveAttributeAsSet(BPI.BranchProtectionPAuthLR,
"branch-protection-pauth-lr");
AddRemoveAttributeAsSet(BPI.GuardedControlStack, "guarded-control-stack");
}
void TargetCodeGenInfo::initBranchProtectionFnAttributes(
const TargetInfo::BranchProtectionInfo &BPI, llvm::AttrBuilder &FuncAttrs) {
// Only used for initializing attributes in the AttrBuilder, which will not
// contain any of these attributes so no need to remove anything.
if (BPI.SignReturnAddr != LangOptions::SignReturnAddressScopeKind::None) {
FuncAttrs.addAttribute("sign-return-address", BPI.getSignReturnAddrStr());
FuncAttrs.addAttribute("sign-return-address-key", BPI.getSignKeyStr());
}
if (BPI.BranchTargetEnforcement)
FuncAttrs.addAttribute("branch-target-enforcement");
if (BPI.BranchProtectionPAuthLR)
FuncAttrs.addAttribute("branch-protection-pauth-lr");
if (BPI.GuardedControlStack)
FuncAttrs.addAttribute("guarded-control-stack");
}
void TargetCodeGenInfo::setPointerAuthFnAttributes(
const PointerAuthOptions &Opts, llvm::Function &F) {
auto UpdateAttr = [&F](bool AttrShouldExist, StringRef AttrName) {
if (AttrShouldExist && !F.hasFnAttribute(AttrName))
F.addFnAttr(AttrName);
if (!AttrShouldExist && F.hasFnAttribute(AttrName))
F.removeFnAttr(AttrName);
};
UpdateAttr(Opts.ReturnAddresses, "ptrauth-returns");
UpdateAttr((bool)Opts.FunctionPointers, "ptrauth-calls");
UpdateAttr(Opts.AuthTraps, "ptrauth-auth-traps");
UpdateAttr(Opts.IndirectGotos, "ptrauth-indirect-gotos");
UpdateAttr(Opts.AArch64JumpTableHardening, "aarch64-jump-table-hardening");
}
void TargetCodeGenInfo::initPointerAuthFnAttributes(
const PointerAuthOptions &Opts, llvm::AttrBuilder &FuncAttrs) {
if (Opts.ReturnAddresses)
FuncAttrs.addAttribute("ptrauth-returns");
if (Opts.FunctionPointers)
FuncAttrs.addAttribute("ptrauth-calls");
if (Opts.AuthTraps)
FuncAttrs.addAttribute("ptrauth-auth-traps");
if (Opts.IndirectGotos)
FuncAttrs.addAttribute("ptrauth-indirect-gotos");
if (Opts.AArch64JumpTableHardening)
FuncAttrs.addAttribute("aarch64-jump-table-hardening");
}
namespace {
class DefaultTargetCodeGenInfo : public TargetCodeGenInfo {
public:
DefaultTargetCodeGenInfo(CodeGen::CodeGenTypes &CGT)
: TargetCodeGenInfo(std::make_unique<DefaultABIInfo>(CGT)) {}
};
} // namespace
std::unique_ptr<TargetCodeGenInfo>
CodeGen::createDefaultTargetCodeGenInfo(CodeGenModule &CGM) {
return std::make_unique<DefaultTargetCodeGenInfo>(CGM.getTypes());
}