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support for compiling type-based switches to C++

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This commit is contained in:
Vern Paxson 2021-12-23 11:39:58 -08:00
parent c6cd5d7a3b
commit 721d99636e
5 changed files with 103 additions and 10 deletions
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98
src/script_opt/CPP/Stmts.cc
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@ -233,6 +233,104 @@ void CPPCompile::GenSwitchStmt(const SwitchStmt* sw)
auto e = sw->StmtExpr();
auto cases = sw->Cases();
if ( sw->TypeMap()->empty() )
GenValueSwitchStmt(e, cases);
else
GenTypeSwitchStmt(e, cases);
}
void CPPCompile::GenTypeSwitchStmt(const Expr* e, const case_list* cases)
{
// Start a scoping block so we avoid naming conflicts if a function
// has multiple type switches.
Emit("{");
Emit("static std::vector<int> CPP__switch_types =");
StartBlock();
for ( const auto& c : *cases )
{
auto tc = c->TypeCases();
if ( tc )
for ( auto id : *tc )
Emit(Fmt(TypeOffset(id->GetType())) + ",");
}
EndBlock(true);
NL();
Emit("ValPtr CPP__sw_val = %s;", GenExpr(e, GEN_VAL_PTR));
Emit("auto& CPP__sw_val_t = CPP__sw_val->GetType();");
Emit("int CPP__sw_type_ind = 0;");
Emit("for ( auto CPP__st : CPP__switch_types )");
StartBlock();
Emit("if ( can_cast_value_to_type(CPP__sw_val.get(), CPP__Type__[CPP__st].get()) )");
Emit("\tbreak;");
Emit("++CPP__sw_type_ind;");
EndBlock();
Emit("switch ( CPP__sw_type_ind ) {");
++break_level;
int case_offset = 0;
for ( const auto& c : *cases )
{
auto tc = c->TypeCases();
if ( tc )
{
bool is_multi = tc->size() > 1;
for ( auto id : *tc )
GenTypeSwitchCase(id, case_offset++, is_multi);
}
else
Emit("default:");
StartBlock();
GenStmt(c->Body());
EndBlock();
}
--break_level;
Emit("}"); // end the switch
Emit("}"); // end the scoping block
}
void CPPCompile::GenTypeSwitchCase(const ID* id, int case_offset, bool is_multi)
{
Emit("case %s:", Fmt(case_offset));
if ( ! id->Name() )
// No assignment, we're done.
return;
// It's an assignment case. If it's a collection of multiple cases,
// assign to the variable only for this particular case.
IndentUp();
if ( is_multi )
{
Emit("if ( CPP__sw_type_ind == %s )", Fmt(case_offset));
IndentUp();
}
auto targ_val = "CPP__sw_val.get()";
auto targ_type = string("CPP__Type__[CPP__switch_types[") + Fmt(case_offset) + "]].get()";
auto cast = string("cast_value_to_type(") + targ_val + ", " + targ_type + ")";
Emit("%s = %s;", LocalName(id), GenericValPtrToGT(cast, id->GetType(), GEN_NATIVE));
IndentDown();
if ( is_multi )
IndentDown();
}
void CPPCompile::GenValueSwitchStmt(const Expr* e, const case_list* cases)
{
auto e_it = e->GetType()->InternalType();
bool is_int = e_it == TYPE_INTERNAL_INT;
bool is_uint = e_it == TYPE_INTERNAL_UNSIGNED;