ldc/gen/semantic-dcompute.cpp
2023-11-06 01:10:16 +01:00

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//===-- semantic-dcompute.cpp ---------------------------------------------===//
//
// LDC the LLVM D compiler
//
// This file is distributed under the BSD-style LDC license. See the LICENSE
// file for details.
//
//===----------------------------------------------------------------------===//
//
// Validation for @compute code:
// enforce: @nogc, nothrow, all function calls are to modules that are also
// @compute. The enforcemnt of nothrow is simpler because all functions
// are assumed to not throw. We only need to check for ThrowStatement.
// We dont use dmd's nothrow detection because it still allows errors.
//
// ban: classes, interfaces, asm, typeid, global variables, synhronized,
// associative arrays, pragma(lib,...)
//
//===----------------------------------------------------------------------===//
#include "dmd/declaration.h"
#include "dmd/expression.h"
#include "dmd/id.h"
#include "dmd/identifier.h"
#include "dmd/module.h"
#include "dmd/template.h"
#include "gen/dcompute/target.h"
#include "gen/logger.h"
#include "gen/recursivevisitor.h"
#include "gen/uda.h"
struct DComputeSemanticAnalyser : public StoppableVisitor {
FuncDeclaration *currentFunction;
// In @compute code only calls to other functions in `@compute` code are
// allowed.
// However, a @kernel function taking a template alias function parameter is
// allowed, but while the alias appears in the symbol table of the module of
// the
// template declaration, it's module of origin is the module at the point of
// instansiation so we need to check for that.
bool isNonComputeCallExpVaild(CallExp *ce) {
FuncDeclaration *f = ce->f;
if (f->ident == Id::dcReflect)
return true;
if (currentFunction == nullptr)
return false;
TemplateInstance *inst = currentFunction->isInstantiated();
if (!inst)
return false;
Objects *tiargs = inst->tiargs;
size_t i = 0, len = tiargs->length;
IF_LOG Logger::println("checking against: %s (%p) (dyncast=%d)",
f->toPrettyChars(), (void *)f, f->dyncast());
LOG_SCOPE
for (; i < len; i++) {
RootObject *o = (*tiargs)[i];
if (o->dyncast() != DYNCAST_EXPRESSION)
continue;
Expression *e = (Expression *)o;
if (e->op != EXP::function_)
continue;
if (f->equals((((FuncExp *)e)->fd))) {
IF_LOG Logger::println("match");
return true;
}
}
return false;
}
using StoppableVisitor::visit;
void visit(InterfaceDeclaration *decl) override {
error(decl->loc, "interfaces and classes not allowed in `@compute` code");
stop = true;
}
void visit(ClassDeclaration *decl) override {
error(decl->loc, "interfaces and classes not allowed in `@compute` code");
stop = true;
}
void visit(VarDeclaration *decl) override {
// Don't print multiple errors for 'synchronized'. see visit(CallExp*)
if (decl->isDataseg()) {
if (strncmp(decl->toChars(), "__critsec", 9) &&
strncmp(decl->toChars(), "typeid", 6)) {
error(decl->loc, "global variables not allowed in `@compute` code");
}
// Ignore typeid: it is ignored by codegen.
stop = true;
return;
}
if (decl->type->ty == TY::Taarray) {
error(decl->loc, "associative arrays not allowed in `@compute` code");
stop = true;
}
// includes interfaces
else if (decl->type->ty == TY::Tclass) {
error(decl->loc, "interfaces and classes not allowed in `@compute` code");
}
}
void visit(PragmaDeclaration *decl) override {
if (decl->ident == Id::lib) {
error(decl->loc,
"linking additional libraries not supported in `@compute` code");
stop = true;
}
}
// Nogc enforcement.
// No need to check AssocArrayLiteral because AA's are banned anyway
void visit(ArrayLiteralExp *e) override {
if (e->type->ty != TY::Tarray || !e->elements || !e->elements->length)
return;
error(e->loc, "array literal in `@compute` code not allowed");
stop = true;
}
void visit(NewExp *e) override {
error(e->loc, "cannot use `new` in `@compute` code");
stop = true;
}
void visit(DeleteExp *e) override {
error(e->loc, "cannot use `delete` in `@compute` code");
stop = true;
}
// No need to check IndexExp because AA's are banned anyway
void visit(AssignExp *e) override {
if (e->e1->op == EXP::arrayLength) {
error(e->loc, "setting `length` in `@compute` code not allowed");
stop = true;
}
}
void visit(CatAssignExp *e) override {
error(e->loc, "cannot use operator `~=` in `@compute` code");
stop = true;
}
void visit(CatExp *e) override {
error(e->loc, "cannot use operator `~` in `@compute` code");
stop = true;
}
// Ban typeid(T)
void visit(TypeidExp *e) override {
error(e->loc, "typeinfo not available in `@compute` code");
stop = true;
}
void visit(StringExp *e) override {
error(e->loc, "string literals not allowed in `@compute` code");
stop = true;
}
void visit(CompoundAsmStatement *e) override {
error(e->loc, "asm not allowed in `@compute` code");
stop = true;
}
void visit(AsmStatement *e) override {
error(e->loc, "asm not allowed in `@compute` code");
stop = true;
}
// Enforce nothrow. Disallow 'catch' as it is dead code.
// try...finally is allowed to facilitate scope(exit)
void visit(TryCatchStatement *e) override {
error(e->loc, "no exceptions in `@compute` code");
stop = true;
}
void visit(ThrowStatement *e) override {
error(e->loc, "no exceptions in `@compute` code");
stop = true;
}
void visit(SwitchStatement *e) override {
if (auto ce = e->condition->isCallExp()) {
if (ce->f->ident == Id::__switch) {
error(e->loc, "cannot `switch` on strings in `@compute` code");
stop = true;
}
}
}
void visit(IfStatement *stmt) override {
// Don't descend into ctfe only code
if (auto ve = stmt->condition->isVarExp()) {
if (ve->var->ident == Id::ctfe) {
if (stmt->elsebody)
visit(stmt->elsebody);
stop = true;
}
} else if (auto ne = stmt->condition->isNotExp()) {
if (auto ve = ne->e1->isVarExp()) {
if (ve->var->ident == Id::ctfe) {
visit(stmt->ifbody);
stop = true;
}
}
}
// Code inside an if(__dcompute_reflect(0,0)) { ...} is explicitly
// for the host and is therefore allowed to call non @compute functions.
// Thus, the if-statement body's code should not be checked for
// @compute semantics and the recursive visitor should stop here.
if (auto ce = stmt->condition->isCallExp()) {
if (ce->f && ce->f->ident == Id::dcReflect) {
auto arg1 = (DComputeTarget::ID)(*ce->arguments)[0]->toInteger();
if (arg1 == DComputeTarget::ID::Host)
stop = true;
}
}
}
void visit(CallExp *e) override {
// SynchronizedStatement is lowered to
// Critsec __critsec105; // 105 == line number
// _d_criticalenter(& __critsec105); <--
// ... |
// _d_criticalexit( & __critsec105); |
// So we intercept it with the CallExp ----
if (e->f->ident == Id::criticalenter) {
error(e->loc, "cannot use `synchronized` in `@compute` code");
stop = true;
return;
}
if (e->f->ident == Id::criticalexit) {
stop = true;
return;
}
Module *m = e->f->getModule();
if ((m == nullptr || (hasComputeAttr(m) == DComputeCompileFor::hostOnly)) &&
!isNonComputeCallExpVaild(e)) {
error(e->loc, "can only call functions from other `@compute` modules in "
"`@compute` code");
stop = true;
}
}
void visit(FuncDeclaration *fd) override {
if (hasKernelAttr(fd) && fd->vthis) {
error(fd->loc, "`@kernel` functions must not require `this`");
stop = true;
return;
}
IF_LOG Logger::println("current function = %s", fd->toChars());
currentFunction = fd;
}
void visit(TemplateDeclaration*) override {
// Don't try to analyse uninstansiated templates.
stop = true;
}
void visit(TemplateInstance *ti) override {
// object.RTInfo(Impl) template instantiations are skipped during codegen,
// as they contain unsupported global variables.
if (ti->tempdecl == Type::rtinfo || ti->tempdecl == Type::rtinfoImpl) {
stop = true;
}
}
// Override the default assert(0) behavior of Visitor:
void visit(Statement *) override {} // do nothing
void visit(Expression *) override {} // do nothing
void visit(Declaration *) override {} // do nothing
void visit(Initializer *) override {} // do nothing
void visit(Dsymbol *) override {} // do nothing
};
void dcomputeSemanticAnalysis(Module *m) {
DComputeSemanticAnalyser v;
RecursiveWalker r(&v);
for (unsigned k = 0; k < m->members->length; k++) {
Dsymbol *dsym = (*m->members)[k];
assert(dsym);
IF_LOG Logger::println("dcomputeSema: %s: %s", m->toPrettyChars(),
dsym->toPrettyChars());
LOG_SCOPE
v.currentFunction = nullptr;
dsym->accept(&r);
}
}