ldc/gen/naked.cpp
2024-07-16 16:22:35 +02:00

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//===-- naked.cpp ---------------------------------------------------------===//
//
// LDC the LLVM D compiler
//
// This file is distributed under the BSD-style LDC license. See the LICENSE
// file for details.
//
//===----------------------------------------------------------------------===//
#include "dmd/declaration.h"
#include "dmd/errors.h"
#include "dmd/expression.h"
#include "dmd/identifier.h"
#include "dmd/mangle.h"
#include "dmd/statement.h"
#include "dmd/template.h"
#include "gen/dvalue.h"
#include "gen/funcgenstate.h"
#include "gen/irstate.h"
#include "gen/llvm.h"
#include "gen/llvmhelpers.h"
#include "gen/logger.h"
#include "gen/tollvm.h"
#include "ir/irfunction.h"
#include "llvm/IR/InlineAsm.h"
#include <cassert>
using namespace dmd;
////////////////////////////////////////////////////////////////////////////////
// FIXME: Integrate these functions
void AsmStatement_toNakedIR(InlineAsmStatement *stmt, IRState *irs);
////////////////////////////////////////////////////////////////////////////////
class ToNakedIRVisitor : public Visitor {
IRState *irs;
public:
explicit ToNakedIRVisitor(IRState *irs) : irs(irs) {}
//////////////////////////////////////////////////////////////////////////
// Import all functions from class Visitor
using Visitor::visit;
//////////////////////////////////////////////////////////////////////////
void visit(Statement *stmt) override {
error(stmt->loc, "Statement not allowed in naked function");
}
//////////////////////////////////////////////////////////////////////////
void visit(InlineAsmStatement *stmt) override {
AsmStatement_toNakedIR(stmt, irs);
}
//////////////////////////////////////////////////////////////////////////
void visit(CompoundStatement *stmt) override {
IF_LOG Logger::println("CompoundStatement::toNakedIR(): %s",
stmt->loc.toChars());
LOG_SCOPE;
if (stmt->statements) {
for (auto s : *stmt->statements) {
if (s) {
s->accept(this);
}
}
}
}
//////////////////////////////////////////////////////////////////////////
void visit(ExpStatement *stmt) override {
IF_LOG Logger::println("ExpStatement::toNakedIR(): %s",
stmt->loc.toChars());
LOG_SCOPE;
// This happens only if there is a ; at the end:
// asm { naked; ... };
// Is this a legal AST?
if (!stmt->exp) {
return;
}
// only expstmt supported in declarations
if (!stmt->exp || stmt->exp->op != EXP::declaration) {
visit(static_cast<Statement *>(stmt));
return;
}
DeclarationExp *d = static_cast<DeclarationExp *>(stmt->exp);
VarDeclaration *vd = d->declaration->isVarDeclaration();
FuncDeclaration *fd = d->declaration->isFuncDeclaration();
EnumDeclaration *ed = d->declaration->isEnumDeclaration();
// and only static variable/function declaration
// no locals or nested stuffies!
if (!vd && !fd && !ed) {
visit(static_cast<Statement *>(stmt));
return;
}
if (vd && !(vd->storage_class & (STCstatic | STCmanifest))) {
error(vd->loc, "non-static variable `%s` not allowed in naked function",
vd->toChars());
return;
}
if (fd && !fd->isStatic()) {
error(fd->loc,
"non-static nested function `%s` not allowed in naked function",
fd->toChars());
return;
}
// enum decls should always be safe
// make sure the symbols gets processed
// TODO: codegen() here is likely incorrect
Declaration_codegen(d->declaration, irs);
}
//////////////////////////////////////////////////////////////////////////
void visit(LabelStatement *stmt) override {
IF_LOG Logger::println("LabelStatement::toNakedIR(): %s",
stmt->loc.toChars());
LOG_SCOPE;
printLabelName(irs->nakedAsm, mangleExact(irs->func()->decl),
stmt->ident->toChars());
irs->nakedAsm << ":";
if (stmt->statement) {
stmt->statement->accept(this);
}
}
};
////////////////////////////////////////////////////////////////////////////////
void DtoDefineNakedFunction(FuncDeclaration *fd) {
IF_LOG Logger::println("DtoDefineNakedFunction(%s)", mangleExact(fd));
LOG_SCOPE;
// we need to do special processing on the body, since we only want
// to allow actual inline asm blocks to reach the final asm output
std::ostringstream &asmstr = gIR->nakedAsm;
// build function header
// FIXME: could we perhaps use llvm asmwriter to give us these details ?
const char *mangle = mangleExact(fd);
std::string fullmangle; // buffer only
const auto &triple = *global.params.targetTriple;
bool const isWin = triple.isOSWindows();
bool const isDarwin = triple.isOSDarwin();
// osx is different
// also mangling has an extra underscore prefixed
if (isDarwin) {
fullmangle += '_';
fullmangle += mangle;
mangle = fullmangle.c_str();
asmstr << "\t.section\t__TEXT,__text,regular,pure_instructions"
<< std::endl;
asmstr << "\t.globl\t" << mangle << std::endl;
if (fd->isInstantiated()) {
asmstr << "\t.weak_definition\t" << mangle << std::endl;
}
asmstr << "\t.p2align\t4, 0x90" << std::endl;
asmstr << mangle << ":" << std::endl;
}
// Windows is different
else if (isWin) {
// mangled names starting with '?' (MSVC++ symbols) apparently need quoting
if (mangle[0] == '?') {
fullmangle += '"';
fullmangle += mangle;
fullmangle += '"';
mangle = fullmangle.c_str();
} else if (triple.isArch32Bit()) {
// prepend extra underscore for Windows x86
fullmangle += '_';
fullmangle += mangle;
mangle = fullmangle.c_str();
}
asmstr << "\t.def\t" << mangle << ";" << std::endl;
// hard code these two numbers for now since gas ignores .scl and llvm
// is defaulting to .type 32 for everything I have seen
asmstr << "\t.scl\t2;" << std::endl;
asmstr << "\t.type\t32;" << std::endl;
asmstr << "\t.endef" << std::endl;
if (fd->isInstantiated()) {
asmstr << "\t.section\t.text,\"xr\",discard," << mangle << std::endl;
} else {
asmstr << "\t.text" << std::endl;
}
asmstr << "\t.globl\t" << mangle << std::endl;
asmstr << "\t.p2align\t4, 0x90" << std::endl;
asmstr << mangle << ":" << std::endl;
} else {
if (fd->isInstantiated()) {
asmstr << "\t.section\t.text." << mangle << ",\"axG\",@progbits,"
<< mangle << ",comdat" << std::endl;
asmstr << "\t.weak\t" << mangle << std::endl;
} else {
asmstr << "\t.text" << std::endl;
asmstr << "\t.globl\t" << mangle << std::endl;
}
asmstr << "\t.p2align\t4, 0x90" << std::endl;
asmstr << "\t.type\t" << mangle << ",@function" << std::endl;
asmstr << mangle << ":" << std::endl;
}
// emit body
ToNakedIRVisitor v(gIR);
fd->fbody->accept(&v);
// We could have generated new errors in toNakedIR(), but we are in codegen
// already so we have to abort here.
if (global.errors) {
fatal();
}
// emit size after body
// llvm does this on linux, but not on osx or Win
if (!(isWin || isDarwin)) {
asmstr << "\t.size\t" << mangle << ", .-" << mangle << std::endl
<< std::endl;
}
gIR->module.appendModuleInlineAsm(asmstr.str());
asmstr.str("");
if (global.params.dllexport ||
(global.params.targetTriple->isOSWindows() && fd->isExport())) {
// Embed a linker switch telling the MS linker to export the naked function.
// This mimics the effect of the dllexport attribute for regular functions.
const auto linkerSwitch = std::string("/EXPORT:") + mangle;
gIR->addLinkerOption(llvm::StringRef(linkerSwitch));
}
}
////////////////////////////////////////////////////////////////////////////////
void emitABIReturnAsmStmt(IRAsmBlock *asmblock, const Loc &loc,
FuncDeclaration *fdecl) {
IF_LOG Logger::println("emitABIReturnAsmStmt(%s)", mangleExact(fdecl));
LOG_SCOPE;
auto as = new IRAsmStmt;
LLType *llretTy = DtoType(fdecl->type->nextOf());
asmblock->retty = llretTy;
asmblock->retn = 1;
// FIXME: This should probably be handled by the TargetABI somehow.
// It should be able to do this for a greater variety of types.
const auto &triple = *global.params.targetTriple;
Type *const rt = fdecl->type->nextOf()->toBasetype();
// x86
if (triple.getArch() == llvm::Triple::x86) {
if (rt->isintegral() || rt->ty == TY::Tpointer || rt->ty == TY::Tclass ||
rt->ty == TY::Taarray) {
if (size(rt) == 8) {
as->out.c = "=A,";
} else {
as->out.c = "={ax},";
}
} else if (rt->isfloating()) {
if (rt->iscomplex()) {
if (fdecl->_linkage == LINK::d) {
// extern(D) always returns on the FPU stack
as->out.c = "={st},={st(1)},";
asmblock->retn = 2;
} else if (rt->ty == TY::Tcomplex32) {
// non-extern(D) cfloat is returned as i64
as->out.c = "=A,";
asmblock->retty = LLType::getInt64Ty(gIR->context());
} else {
// non-extern(D) cdouble and creal are returned via sret
// don't add anything!
asmblock->retty = LLType::getVoidTy(gIR->context());
asmblock->retn = 0;
return;
}
} else {
as->out.c = "={st},";
}
} else if (rt->ty == TY::Tarray || rt->ty == TY::Tdelegate) {
as->out.c = "={ax},={dx},";
asmblock->retn = 2;
#if 0
// this is to show how to allocate a temporary for the return value
// in case the appropriate multi register constraint isn't supported.
// this way abi return from inline asm can still be emulated.
// note that "$<<out0>>" etc in the asm will translate to the correct
// numbered output when the asm block in finalized
// generate asm
as->out.c = "=*m,=*m,";
LLValue* tmp = DtoRawAlloca(llretTy, 0, ".tmp_asm_ret");
as->out.push_back( tmp );
as->out.push_back( DtoGEP(tmp, 0, 1) );
as->code = "movd %eax, $<<out0>>" "\n\t" "mov %edx, $<<out1>>";
// fix asmblock
asmblock->retn = 0;
asmblock->retemu = true;
asmblock->asmBlock->abiret = tmp;
// add "ret" stmt at the end of the block
asmblock->s.push_back(as);
// done, we don't want anything pushed in the front of the block
return;
#endif
} else {
error(loc, "unimplemented return type `%s` for implicit abi return",
rt->toChars());
fatal();
}
}
// x86_64
else if (triple.getArch() == llvm::Triple::x86_64) {
if (rt->isintegral() || rt->ty == TY::Tpointer || rt->ty == TY::Tclass ||
rt->ty == TY::Taarray) {
as->out.c = "={ax},";
} else if (rt->isfloating()) {
const bool isWin64 = triple.isOSWindows();
if (rt == Type::tcomplex80 && !isWin64) {
// On x87 stack, re=st, im=st(1)
as->out.c = "={st},={st(1)},";
asmblock->retn = 2;
} else if ((rt == Type::tfloat80 || rt == Type::timaginary80) &&
!triple.isWindowsMSVCEnvironment()) {
// On x87 stack
as->out.c = "={st},";
} else if (rt == Type::tcomplex32) {
if (isWin64) {
// cfloat on Win64 -> %rax
as->out.c = "={ax},";
asmblock->retty = LLType::getInt64Ty(gIR->context());
} else {
// cfloat on Posix -> %xmm0 (extract two floats)
as->out.c = "={xmm0},";
asmblock->retty = LLType::getDoubleTy(gIR->context());
}
} else if (rt->iscomplex()) {
if (isWin64) {
// Win64: cdouble and creal are returned via sret
// don't add anything!
asmblock->retty = LLType::getVoidTy(gIR->context());
asmblock->retn = 0;
return;
} else {
// cdouble on Posix -> re=%xmm0, im=%xmm1
as->out.c = "={xmm0},={xmm1},";
asmblock->retn = 2;
}
} else {
// Plain float/double/ifloat/idouble
as->out.c = "={xmm0},";
}
} else if (rt->ty == TY::Tarray || rt->ty == TY::Tdelegate) {
as->out.c = "={ax},={dx},";
asmblock->retn = 2;
} else {
error(loc, "unimplemented return type `%s` for implicit abi return",
rt->toChars());
fatal();
}
}
// unsupported
else {
error(loc,
"this target (%s) does not implement inline asm falling off the end "
"of the function",
triple.str().c_str());
fatal();
}
// return values always go in the front
asmblock->s.push_front(as);
}
////////////////////////////////////////////////////////////////////////////////
// sort of kinda related to naked ...
DValue *DtoInlineAsmExpr(const Loc &loc, FuncDeclaration *fd,
Expressions *arguments, LLValue *sretPointer) {
assert(fd->toParent()->isTemplateInstance() && "invalid inline __asm expr");
assert(arguments->length >= 2 && "invalid __asm call");
// get code param
Expression *e = (*arguments)[0];
IF_LOG Logger::println("code exp: %s", e->toChars());
StringExp *se = static_cast<StringExp *>(e);
if (e->op != EXP::string_ || se->sz != 1) {
error(e->loc, "`__asm` code argument is not a `char[]` string literal");
fatal();
}
const DString codeStr = se->peekString();
const llvm::StringRef code = {codeStr.ptr, codeStr.length};
// get constraints param
e = (*arguments)[1];
IF_LOG Logger::println("constraint exp: %s", e->toChars());
se = static_cast<StringExp *>(e);
if (e->op != EXP::string_ || se->sz != 1) {
error(e->loc,
"`__asm` constraints argument is not a `char[]` string literal");
fatal();
}
const DString constraintsStr = se->peekString();
const llvm::StringRef constraints = {constraintsStr.ptr,
constraintsStr.length};
auto constraintInfo = llvm::InlineAsm::ParseConstraints(constraints);
// build runtime arguments
const size_t n = arguments->length - 2;
LLSmallVector<LLValue *, 8> operands;
LLSmallVector<LLType *, 8> indirectTypes;
operands.reserve(n);
Type *returnType = fd->type->nextOf();
const size_t cisize = constraintInfo.size();
const size_t minRequired = n + (returnType->ty == TY::Tvoid ? 0 : 1);
if (cisize < minRequired) {
error(se->loc,
"insufficient number of constraints (%zu) for number of additional "
"arguments %s(%zu)",
cisize, returnType->ty == TY::Tvoid ? "" : "and return type ",
minRequired);
fatal();
}
size_t i = 0;
for (; i < n; i++) {
Expression *ee = (*arguments)[2 + i];
operands.push_back(DtoRVal(ee));
if (constraintInfo[i].isIndirect) {
if (TypePointer *pt = ee->type->isTypePointer())
indirectTypes.push_back(DtoType(pt->nextOf()));
else
indirectTypes.push_back(DtoType(ee->type));
}
}
LLType *irReturnType = DtoType(returnType->toBasetype());
for (; i < cisize; i++) {
if (!constraintInfo[i].isIndirect)
continue;
if (constraintInfo[i].Type == llvm::InlineAsm::ConstraintPrefix::isOutput) {
indirectTypes.push_back(DtoType(returnType));
} else {
error(loc, "indirect constraint %d doesn't correspond to an argument or output", (unsigned)i);
fatal();
}
}
LLValue *rv =
DtoInlineAsmExpr(loc, code, constraints, operands, indirectTypes, irReturnType);
// work around missing tuple support for users of the return value
if (sretPointer || returnType->ty == TY::Tstruct) {
auto lvalue = sretPointer;
if (!lvalue)
lvalue = DtoAlloca(returnType, ".__asm_tuple_ret");
DtoStore(rv, lvalue);
return new DLValue(returnType, lvalue);
}
// return call as im value
return new DImValue(returnType, rv);
}
llvm::CallInst *DtoInlineAsmExpr(const Loc &loc, llvm::StringRef code,
llvm::StringRef constraints,
llvm::ArrayRef<llvm::Value *> operands,
llvm::ArrayRef<llvm::Type *> indirectTypes,
llvm::Type *returnType) {
IF_LOG Logger::println("DtoInlineAsmExpr @ %s", loc.toChars());
LOG_SCOPE;
LLSmallVector<LLType *, 8> operandTypes;
operandTypes.reserve(operands.size());
for (auto *o : operands)
operandTypes.push_back(o->getType());
// build asm function type
llvm::FunctionType *FT =
llvm::FunctionType::get(returnType, operandTypes, false);
if (auto err = llvm::InlineAsm::verify(FT, constraints)) {
error(loc, "inline asm constraints are invalid");
llvm::errs() << err;
fatal();
}
// build asm call
bool sideeffect = true;
llvm::InlineAsm *ia = llvm::InlineAsm::get(FT, code, constraints, sideeffect);
auto call = gIR->createInlineAsmCall(loc, ia, operands, indirectTypes);
return call;
}