blob: 69d01c8e9797751f22eda5c92d41396602b4490c [file] [log] [blame]
/* Compiler implementation of the D programming language
* Copyright (C) 1999-2019 by The D Language Foundation, All Rights Reserved
* written by Walter Bright
* http://www.digitalmars.com
* Distributed under the Boost Software License, Version 1.0.
* http://www.boost.org/LICENSE_1_0.txt
* https://github.com/D-Programming-Language/dmd/blob/master/src/escape.c
*/
#include "mars.h"
#include "init.h"
#include "expression.h"
#include "scope.h"
#include "aggregate.h"
#include "declaration.h"
#include "module.h"
/************************************
* Aggregate the data collected by the escapeBy??() functions.
*/
struct EscapeByResults
{
VarDeclarations byref; // array into which variables being returned by ref are inserted
VarDeclarations byvalue; // array into which variables with values containing pointers are inserted
FuncDeclarations byfunc; // nested functions that are turned into delegates
Expressions byexp; // array into which temporaries being returned by ref are inserted
};
static bool checkReturnEscapeImpl(Scope *sc, Expression *e, bool refs, bool gag);
static void inferReturn(FuncDeclaration *fd, VarDeclaration *v);
static void escapeByValue(Expression *e, EscapeByResults *er);
static void escapeByRef(Expression *e, EscapeByResults *er);
static void findAllOuterAccessedVariables(FuncDeclaration *fd, VarDeclarations *vars);
/* 'v' is assigned unsafely to 'par'
*/
static void unsafeAssign(Scope *sc, FuncDeclaration *fdc, Identifier *par, Expression *arg, bool gag,
bool &result, VarDeclaration *v, const char *desc)
{
if (global.params.vsafe && sc->func->setUnsafe())
{
if (!gag)
error(arg->loc, "%s %s assigned to non-scope parameter %s calling %s",
desc, v->toChars(),
par ? par->toChars() : "unnamed",
fdc ? fdc->toPrettyChars() : "indirectly");
result = true;
}
}
/****************************************
* Function parameter par is being initialized to arg,
* and par may escape.
* Detect if scoped values can escape this way.
* Print error messages when these are detected.
* Params:
* sc = used to determine current function and module
* par = identifier of function parameter
* arg = initializer for param
* gag = do not print error messages
* Returns:
* true if pointers to the stack can escape via assignment
*/
bool checkParamArgumentEscape(Scope *sc, FuncDeclaration *fdc, Identifier *par, Expression *arg, bool gag)
{
//printf("checkParamArgumentEscape(arg: %s par: %s)\n", arg->toChars(), par->toChars());
//printf("type = %s, %d\n", arg->type->toChars(), arg->type->hasPointers());
if (!arg->type->hasPointers())
return false;
EscapeByResults er;
escapeByValue(arg, &er);
if (!er.byref.dim && !er.byvalue.dim && !er.byfunc.dim && !er.byexp.dim)
return false;
bool result = false;
for (size_t i = 0; i < er.byvalue.dim; i++)
{
//printf("byvalue %s\n", v->toChars());
VarDeclaration *v = er.byvalue[i];
if (v->isDataseg())
continue;
Dsymbol *p = v->toParent2();
v->storage_class &= ~STCmaybescope;
if (v->isScope())
{
unsafeAssign(sc, fdc, par, arg, gag, result, v, "scope variable");
}
else if (v->storage_class & STCvariadic && p == sc->func)
{
Type *tb = v->type->toBasetype();
if (tb->ty == Tarray || tb->ty == Tsarray)
{
unsafeAssign(sc, fdc, par, arg, gag, result, v, "variadic variable");
}
}
else
{
/* v is not 'scope', and is assigned to a parameter that may escape.
* Therefore, v can never be 'scope'.
*/
v->doNotInferScope = true;
}
}
for (size_t i = 0; i < er.byref.dim; i++)
{
VarDeclaration *v = er.byref[i];
if (v->isDataseg())
continue;
Dsymbol *p = v->toParent2();
v->storage_class &= ~STCmaybescope;
if ((v->storage_class & (STCref | STCout)) == 0 && p == sc->func)
{
unsafeAssign(sc, fdc, par, arg, gag, result, v, "reference to local variable");
continue;
}
}
for (size_t i = 0; i < er.byfunc.dim; i++)
{
FuncDeclaration *fd = er.byfunc[i];
//printf("fd = %s, %d\n", fd->toChars(), fd->tookAddressOf);
VarDeclarations vars;
findAllOuterAccessedVariables(fd, &vars);
for (size_t j = 0; j < vars.dim; j++)
{
VarDeclaration *v = vars[j];
//printf("v = %s\n", v->toChars());
assert(!v->isDataseg()); // these are not put in the closureVars[]
Dsymbol *p = v->toParent2();
v->storage_class &= ~STCmaybescope;
if ((v->storage_class & (STCref | STCout | STCscope)) && p == sc->func)
{
unsafeAssign(sc, fdc, par, arg, gag, result, v, "reference to local");
continue;
}
}
}
for (size_t i = 0; i < er.byexp.dim; i++)
{
Expression *ee = er.byexp[i];
if (sc->func->setUnsafe())
{
if (!gag)
error(ee->loc, "reference to stack allocated value returned by %s assigned to non-scope parameter %s",
ee->toChars(),
par ? par->toChars() : "unnamed");
result = true;
}
}
return result;
}
/****************************************
* Given an AssignExp, determine if the lvalue will cause
* the contents of the rvalue to escape.
* Print error messages when these are detected.
* Infer 'scope' for the lvalue where possible, in order
* to eliminate the error.
* Params:
* sc = used to determine current function and module
* ae = AssignExp to check for any pointers to the stack
* gag = do not print error messages
* Returns:
* true if pointers to the stack can escape via assignment
*/
bool checkAssignEscape(Scope *sc, Expression *e, bool gag)
{
//printf("checkAssignEscape(e: %s)\n", e->toChars());
if (e->op != TOKassign && e->op != TOKblit && e->op != TOKconstruct)
return false;
AssignExp *ae = (AssignExp *)e;
Expression *e1 = ae->e1;
Expression *e2 = ae->e2;
//printf("type = %s, %d\n", e1->type->toChars(), e1->type->hasPointers());
if (!e1->type->hasPointers())
return false;
if (e1->op == TOKslice)
return false;
EscapeByResults er;
escapeByValue(e2, &er);
if (!er.byref.dim && !er.byvalue.dim && !er.byfunc.dim && !er.byexp.dim)
return false;
VarDeclaration *va = NULL;
while (e1->op == TOKdotvar)
e1 = ((DotVarExp *)e1)->e1;
if (e1->op == TOKvar)
va = ((VarExp *)e1)->var->isVarDeclaration();
else if (e1->op == TOKthis)
va = ((ThisExp *)e1)->var->isVarDeclaration();
else if (e1->op == TOKindex)
{
IndexExp *ie = (IndexExp *)e1;
if (ie->e1->op == TOKvar && ie->e1->type->toBasetype()->ty == Tsarray)
va = ((VarExp *)ie->e1)->var->isVarDeclaration();
}
// Try to infer 'scope' for va if in a function not marked @system
bool inferScope = false;
if (va && sc->func && sc->func->type && sc->func->type->ty == Tfunction)
inferScope = ((TypeFunction *)sc->func->type)->trust != TRUSTsystem;
bool result = false;
for (size_t i = 0; i < er.byvalue.dim; i++)
{
VarDeclaration *v = er.byvalue[i];
//printf("byvalue: %s\n", v->toChars());
if (v->isDataseg())
continue;
Dsymbol *p = v->toParent2();
if (!(va && va->isScope()))
v->storage_class &= ~STCmaybescope;
if (v->isScope())
{
if (va && va->isScope() && va->storage_class & STCreturn && !(v->storage_class & STCreturn) &&
sc->func->setUnsafe())
{
if (!gag)
error(ae->loc, "scope variable %s assigned to return scope %s", v->toChars(), va->toChars());
result = true;
continue;
}
// If va's lifetime encloses v's, then error
if (va &&
((va->enclosesLifetimeOf(v) && !(v->storage_class & STCparameter)) ||
// va is class reference
(ae->e1->op == TOKdotvar && va->type->toBasetype()->ty == Tclass && (va->enclosesLifetimeOf(v) || !va->isScope())) ||
va->storage_class & STCref) &&
sc->func->setUnsafe())
{
if (!gag)
error(ae->loc, "scope variable %s assigned to %s with longer lifetime", v->toChars(), va->toChars());
result = true;
continue;
}
if (va && !va->isDataseg() && !va->doNotInferScope)
{
if (!va->isScope() && inferScope)
{ //printf("inferring scope for %s\n", va->toChars());
va->storage_class |= STCscope | STCscopeinferred;
va->storage_class |= v->storage_class & STCreturn;
}
continue;
}
if (sc->func->setUnsafe())
{
if (!gag)
error(ae->loc, "scope variable %s assigned to non-scope %s", v->toChars(), e1->toChars());
result = true;
}
}
else if (v->storage_class & STCvariadic && p == sc->func)
{
Type *tb = v->type->toBasetype();
if (tb->ty == Tarray || tb->ty == Tsarray)
{
if (va && !va->isDataseg() && !va->doNotInferScope)
{
if (!va->isScope() && inferScope)
{ //printf("inferring scope for %s\n", va->toChars());
va->storage_class |= STCscope | STCscopeinferred;
}
continue;
}
if (sc->func->setUnsafe())
{
if (!gag)
error(ae->loc, "variadic variable %s assigned to non-scope %s", v->toChars(), e1->toChars());
result = true;
}
}
}
else
{
/* v is not 'scope', and we didn't check the scope of where we assigned it to.
* It may escape via that assignment, therefore, v can never be 'scope'.
*/
v->doNotInferScope = true;
}
}
for (size_t i = 0; i < er.byref.dim; i++)
{
VarDeclaration *v = er.byref[i];
//printf("byref: %s\n", v->toChars());
if (v->isDataseg())
continue;
Dsymbol *p = v->toParent2();
// If va's lifetime encloses v's, then error
if (va &&
((va->enclosesLifetimeOf(v) && !(v->storage_class & STCparameter)) || va->storage_class & STCref) &&
sc->func->setUnsafe())
{
if (!gag)
error(ae->loc, "address of variable %s assigned to %s with longer lifetime", v->toChars(), va->toChars());
result = true;
continue;
}
if (!(va && va->isScope()))
v->storage_class &= ~STCmaybescope;
if ((v->storage_class & (STCref | STCout)) == 0 && p == sc->func)
{
if (va && !va->isDataseg() && !va->doNotInferScope)
{
if (!va->isScope() && inferScope)
{ //printf("inferring scope for %s\n", va->toChars());
va->storage_class |= STCscope | STCscopeinferred;
}
continue;
}
if (sc->func->setUnsafe())
{
if (!gag)
error(ae->loc, "reference to local variable %s assigned to non-scope %s", v->toChars(), e1->toChars());
result = true;
}
continue;
}
}
for (size_t i = 0; i < er.byfunc.dim; i++)
{
FuncDeclaration *fd = er.byfunc[i];
//printf("fd = %s, %d\n", fd->toChars(), fd->tookAddressOf);
VarDeclarations vars;
findAllOuterAccessedVariables(fd, &vars);
for (size_t j = 0; j < vars.dim; j++)
{
VarDeclaration *v = vars[j];
//printf("v = %s\n", v->toChars());
assert(!v->isDataseg()); // these are not put in the closureVars[]
Dsymbol *p = v->toParent2();
if (!(va && va->isScope()))
v->storage_class &= ~STCmaybescope;
if ((v->storage_class & (STCref | STCout | STCscope)) && p == sc->func)
{
if (va && !va->isDataseg() && !va->doNotInferScope)
{
/* Don't infer STCscope for va, because then a closure
* won't be generated for sc->func.
*/
//if (!va->isScope() && inferScope)
//va->storage_class |= STCscope | STCscopeinferred;
continue;
}
if (sc->func->setUnsafe())
{
if (!gag)
error(ae->loc, "reference to local %s assigned to non-scope %s in @safe code", v->toChars(), e1->toChars());
result = true;
}
continue;
}
}
}
for (size_t i = 0; i < er.byexp.dim; i++)
{
Expression *ee = er.byexp[i];
if (va && !va->isDataseg() && !va->doNotInferScope)
{
if (!va->isScope() && inferScope)
{ //printf("inferring scope for %s\n", va->toChars());
va->storage_class |= STCscope | STCscopeinferred;
}
continue;
}
if (sc->func->setUnsafe())
{
if (!gag)
error(ee->loc, "reference to stack allocated value returned by %s assigned to non-scope %s",
ee->toChars(), e1->toChars());
result = true;
}
}
return result;
}
/************************************
* Detect cases where pointers to the stack can 'escape' the
* lifetime of the stack frame when throwing `e`.
* Print error messages when these are detected.
* Params:
* sc = used to determine current function and module
* e = expression to check for any pointers to the stack
* gag = do not print error messages
* Returns:
* true if pointers to the stack can escape
*/
bool checkThrowEscape(Scope *sc, Expression *e, bool gag)
{
//printf("[%s] checkThrowEscape, e = %s\n", e->loc->toChars(), e->toChars());
EscapeByResults er;
escapeByValue(e, &er);
if (!er.byref.dim && !er.byvalue.dim && !er.byexp.dim)
return false;
bool result = false;
for (size_t i = 0; i < er.byvalue.dim; i++)
{
VarDeclaration *v = er.byvalue[i];
//printf("byvalue %s\n", v->toChars());
if (v->isDataseg())
continue;
if (v->isScope())
{
if (sc->_module && sc->_module->isRoot())
{
// Only look for errors if in module listed on command line
if (global.params.vsafe) // https://issues.dlang.org/show_bug.cgi?id=17029
{
if (!gag)
error(e->loc, "scope variable %s may not be thrown", v->toChars());
result = true;
}
continue;
}
}
else
{
//printf("no infer for %s\n", v->toChars());
v->doNotInferScope = true;
}
}
return result;
}
/************************************
* Detect cases where pointers to the stack can 'escape' the
* lifetime of the stack frame by returning 'e' by value.
* Params:
* sc = used to determine current function and module
* e = expression to check for any pointers to the stack
* gag = do not print error messages
* Returns:
* true if pointers to the stack can escape
*/
bool checkReturnEscape(Scope *sc, Expression *e, bool gag)
{
//printf("[%s] checkReturnEscape, e = %s\n", e->loc->toChars(), e->toChars());
return checkReturnEscapeImpl(sc, e, false, gag);
}
/************************************
* Detect cases where returning 'e' by ref can result in a reference to the stack
* being returned.
* Print error messages when these are detected.
* Params:
* sc = used to determine current function and module
* e = expression to check
* gag = do not print error messages
* Returns:
* true if references to the stack can escape
*/
bool checkReturnEscapeRef(Scope *sc, Expression *e, bool gag)
{
//printf("[%s] checkReturnEscapeRef, e = %s\n", e->loc.toChars(), e->toChars());
//printf("current function %s\n", sc->func->toChars());
//printf("parent2 function %s\n", sc->func->toParent2()->toChars());
return checkReturnEscapeImpl(sc, e, true, gag);
}
static void escapingRef(VarDeclaration *v, Expression *e, bool &result, bool gag)
{
if (!gag)
{
const char *msg;
if (v->storage_class & STCparameter)
msg = "returning `%s` escapes a reference to parameter `%s`, perhaps annotate with `return`";
else
msg = "returning `%s` escapes a reference to local variable `%s`";
error(e->loc, msg, e->toChars(), v->toChars());
}
result = true;
}
static bool checkReturnEscapeImpl(Scope *sc, Expression *e, bool refs, bool gag)
{
//printf("[%s] checkReturnEscapeImpl, e = %s\n", e->loc->toChars(), e->toChars());
EscapeByResults er;
if (refs)
escapeByRef(e, &er);
else
escapeByValue(e, &er);
if (!er.byref.dim && !er.byvalue.dim && !er.byexp.dim)
return false;
bool result = false;
for (size_t i = 0; i < er.byvalue.dim; i++)
{
VarDeclaration *v = er.byvalue[i];
//printf("byvalue %s\n", v->toChars());
if (v->isDataseg())
continue;
Dsymbol *p = v->toParent2();
if ((v->isScope() || (v->storage_class & STCmaybescope)) &&
!(v->storage_class & STCreturn) &&
v->isParameter() &&
sc->func->flags & FUNCFLAGreturnInprocess &&
p == sc->func)
{
inferReturn(sc->func, v); // infer addition of 'return'
continue;
}
if (v->isScope())
{
if (v->storage_class & STCreturn)
continue;
if (sc->_module && sc->_module->isRoot() &&
/* This case comes up when the ReturnStatement of a __foreachbody is
* checked for escapes by the caller of __foreachbody. Skip it.
*
* struct S { static int opApply(int delegate(S*) dg); }
* S* foo() {
* foreach (S* s; S) // create __foreachbody for body of foreach
* return s; // s is inferred as 'scope' but incorrectly tested in foo()
* return null; }
*/
!(!refs && p->parent == sc->func))
{
// Only look for errors if in module listed on command line
if (global.params.vsafe) // https://issues.dlang.org/show_bug.cgi?id=17029
{
if (!gag)
error(e->loc, "scope variable %s may not be returned", v->toChars());
result = true;
}
continue;
}
}
else if (v->storage_class & STCvariadic && p == sc->func)
{
Type *tb = v->type->toBasetype();
if (tb->ty == Tarray || tb->ty == Tsarray)
{
if (!gag)
error(e->loc, "returning `%s` escapes a reference to variadic parameter `%s`", e->toChars(), v->toChars());
result = false;
}
}
else
{
//printf("no infer for %s\n", v->toChars());
v->doNotInferScope = true;
}
}
for (size_t i = 0; i < er.byref.dim; i++)
{
VarDeclaration *v = er.byref[i];
//printf("byref %s\n", v->toChars());
if (v->isDataseg())
continue;
Dsymbol *p = v->toParent2();
if ((v->storage_class & (STCref | STCout)) == 0)
{
if (p == sc->func)
{
escapingRef(v, e, result, gag);
continue;
}
FuncDeclaration *fd = p->isFuncDeclaration();
if (fd && sc->func->flags & FUNCFLAGreturnInprocess)
{
/* Code like:
* int x;
* auto dg = () { return &x; }
* Making it:
* auto dg = () return { return &x; }
* Because dg.ptr points to x, this is returning dt.ptr+offset
*/
if (global.params.vsafe)
sc->func->storage_class |= STCreturn;
}
}
/* Check for returning a ref variable by 'ref', but should be 'return ref'
* Infer the addition of 'return', or set result to be the offending expression.
*/
if ( (v->storage_class & (STCref | STCout)) &&
!(v->storage_class & (STCreturn | STCforeach)))
{
if ((sc->func->flags & FUNCFLAGreturnInprocess) && p == sc->func)
{
inferReturn(sc->func, v); // infer addition of 'return'
}
else if (global.params.useDIP25 &&
sc->_module && sc->_module->isRoot())
{
// Only look for errors if in module listed on command line
if (p == sc->func)
{
//printf("escaping reference to local ref variable %s\n", v->toChars());
//printf("storage class = x%llx\n", v->storage_class);
escapingRef(v, e, result, gag);
continue;
}
// Don't need to be concerned if v's parent does not return a ref
FuncDeclaration *fd = p->isFuncDeclaration();
if (fd && fd->type && fd->type->ty == Tfunction)
{
TypeFunction *tf = (TypeFunction *)fd->type;
if (tf->isref)
{
if (!gag)
error(e->loc, "escaping reference to outer local variable %s", v->toChars());
result = true;
continue;
}
}
}
}
}
for (size_t i = 0; i < er.byexp.dim; i++)
{
Expression *ee = er.byexp[i];
//printf("byexp %s\n", ee->toChars());
if (!gag)
error(ee->loc, "escaping reference to stack allocated value returned by %s", ee->toChars());
result = true;
}
return result;
}
/*************************************
* Variable v needs to have 'return' inferred for it.
* Params:
* fd = function that v is a parameter to
* v = parameter that needs to be STCreturn
*/
static void inferReturn(FuncDeclaration *fd, VarDeclaration *v)
{
// v is a local in the current function
//printf("for function '%s' inferring 'return' for variable '%s'\n", fd->toChars(), v->toChars());
v->storage_class |= STCreturn;
TypeFunction *tf = (TypeFunction *)fd->type;
if (v == fd->vthis)
{
/* v is the 'this' reference, so mark the function
*/
fd->storage_class |= STCreturn;
if (tf->ty == Tfunction)
{
//printf("'this' too %p %s\n", tf, sc->func->toChars());
tf->isreturn = true;
}
}
else
{
// Perform 'return' inference on parameter
if (tf->ty == Tfunction && tf->parameters)
{
const size_t dim = Parameter::dim(tf->parameters);
for (size_t i = 0; i < dim; i++)
{
Parameter *p = Parameter::getNth(tf->parameters, i);
if (p->ident == v->ident)
{
p->storageClass |= STCreturn;
break; // there can be only one
}
}
}
}
}
/****************************************
* e is an expression to be returned by value, and that value contains pointers.
* Walk e to determine which variables are possibly being
* returned by value, such as:
* int* function(int* p) { return p; }
* If e is a form of &p, determine which variables have content
* which is being returned as ref, such as:
* int* function(int i) { return &i; }
* Multiple variables can be inserted, because of expressions like this:
* int function(bool b, int i, int* p) { return b ? &i : p; }
*
* No side effects.
*
* Params:
* e = expression to be returned by value
* er = where to place collected data
*/
static void escapeByValue(Expression *e, EscapeByResults *er)
{
//printf("[%s] escapeByValue, e: %s\n", e->loc.toChars(), e->toChars());
class EscapeVisitor : public Visitor
{
public:
EscapeByResults *er;
EscapeVisitor(EscapeByResults *er)
: er(er)
{
}
void visit(Expression *)
{
}
void visit(AddrExp *e)
{
escapeByRef(e->e1, er);
}
void visit(SymOffExp *e)
{
VarDeclaration *v = e->var->isVarDeclaration();
if (v)
er->byref.push(v);
}
void visit(VarExp *e)
{
VarDeclaration *v = e->var->isVarDeclaration();
if (v)
er->byvalue.push(v);
}
void visit(ThisExp *e)
{
if (e->var)
er->byvalue.push(e->var);
}
void visit(DotVarExp *e)
{
Type *t = e->e1->type->toBasetype();
if (t->ty == Tstruct)
e->e1->accept(this);
}
void visit(DelegateExp *e)
{
Type *t = e->e1->type->toBasetype();
if (t->ty == Tclass || t->ty == Tpointer)
escapeByValue(e->e1, er);
else
escapeByRef(e->e1, er);
er->byfunc.push(e->func);
}
void visit(FuncExp *e)
{
if (e->fd->tok == TOKdelegate)
er->byfunc.push(e->fd);
}
void visit(TupleExp *)
{
assert(0); // should have been lowered by now
}
void visit(ArrayLiteralExp *e)
{
Type *tb = e->type->toBasetype();
if (tb->ty == Tsarray || tb->ty == Tarray)
{
if (e->basis)
e->basis->accept(this);
for (size_t i = 0; i < e->elements->dim; i++)
{
Expression *el = (*e->elements)[i];
if (el)
el->accept(this);
}
}
}
void visit(StructLiteralExp *e)
{
if (e->elements)
{
for (size_t i = 0; i < e->elements->dim; i++)
{
Expression *ex = (*e->elements)[i];
if (ex)
ex->accept(this);
}
}
}
void visit(NewExp *e)
{
Type *tb = e->newtype->toBasetype();
if (tb->ty == Tstruct && !e->member && e->arguments)
{
for (size_t i = 0; i < e->arguments->dim; i++)
{
Expression *ex = (*e->arguments)[i];
if (ex)
ex->accept(this);
}
}
}
void visit(CastExp *e)
{
Type *tb = e->type->toBasetype();
if (tb->ty == Tarray &&
e->e1->type->toBasetype()->ty == Tsarray)
{
escapeByRef(e->e1, er);
}
else
e->e1->accept(this);
}
void visit(SliceExp *e)
{
if (e->e1->op == TOKvar)
{
VarDeclaration *v = ((VarExp *)e->e1)->var->isVarDeclaration();
Type *tb = e->type->toBasetype();
if (v)
{
if (tb->ty == Tsarray)
return;
if (v->storage_class & STCvariadic)
{
er->byvalue.push(v);
return;
}
}
}
Type *t1b = e->e1->type->toBasetype();
if (t1b->ty == Tsarray)
{
Type *tb = e->type->toBasetype();
if (tb->ty != Tsarray)
escapeByRef(e->e1, er);
}
else
e->e1->accept(this);
}
void visit(BinExp *e)
{
Type *tb = e->type->toBasetype();
if (tb->ty == Tpointer)
{
e->e1->accept(this);
e->e2->accept(this);
}
}
void visit(BinAssignExp *e)
{
e->e1->accept(this);
}
void visit(AssignExp *e)
{
e->e1->accept(this);
}
void visit(CommaExp *e)
{
e->e2->accept(this);
}
void visit(CondExp *e)
{
e->e1->accept(this);
e->e2->accept(this);
}
void visit(CallExp *e)
{
//printf("CallExp(): %s\n", e->toChars());
/* Check each argument that is
* passed as 'return scope'.
*/
Type *t1 = e->e1->type->toBasetype();
TypeFunction *tf = NULL;
TypeDelegate *dg = NULL;
if (t1->ty == Tdelegate)
{
dg = (TypeDelegate *)t1;
tf = (TypeFunction *)dg->next;
}
else if (t1->ty == Tfunction)
tf = (TypeFunction *)t1;
else
return;
if (e->arguments && e->arguments->dim)
{
/* j=1 if _arguments[] is first argument,
* skip it because it is not passed by ref
*/
size_t j = (tf->linkage == LINKd && tf->varargs == 1);
for (size_t i = j; i < e->arguments->dim; ++i)
{
Expression *arg = (*e->arguments)[i];
size_t nparams = Parameter::dim(tf->parameters);
if (i - j < nparams && i >= j)
{
Parameter *p = Parameter::getNth(tf->parameters, i - j);
const StorageClass stc = tf->parameterStorageClass(p);
if ((stc & (STCscope)) && (stc & STCreturn))
arg->accept(this);
else if ((stc & (STCref)) && (stc & STCreturn))
escapeByRef(arg, er);
}
}
}
// If 'this' is returned, check it too
if (e->e1->op == TOKdotvar && t1->ty == Tfunction)
{
DotVarExp *dve = (DotVarExp *)e->e1;
FuncDeclaration *fd = dve->var->isFuncDeclaration();
AggregateDeclaration *ad = NULL;
if (global.params.vsafe && tf->isreturn && fd && (ad = fd->isThis()) != NULL)
{
if (ad->isClassDeclaration() || tf->isscope) // this is 'return scope'
dve->e1->accept(this);
else if (ad->isStructDeclaration()) // this is 'return ref'
escapeByRef(dve->e1, er);
}
else if (dve->var->storage_class & STCreturn || tf->isreturn)
{
if (dve->var->storage_class & STCscope)
dve->e1->accept(this);
else if (dve->var->storage_class & STCref)
escapeByRef(dve->e1, er);
}
}
/* If returning the result of a delegate call, the .ptr
* field of the delegate must be checked.
*/
if (dg)
{
if (tf->isreturn)
e->e1->accept(this);
}
}
};
EscapeVisitor v(er);
e->accept(&v);
}
/****************************************
* e is an expression to be returned by 'ref'.
* Walk e to determine which variables are possibly being
* returned by ref, such as:
* ref int function(int i) { return i; }
* If e is a form of *p, determine which variables have content
* which is being returned as ref, such as:
* ref int function(int* p) { return *p; }
* Multiple variables can be inserted, because of expressions like this:
* ref int function(bool b, int i, int* p) { return b ? i : *p; }
*
* No side effects.
*
* Params:
* e = expression to be returned by 'ref'
* er = where to place collected data
*/
static void escapeByRef(Expression *e, EscapeByResults *er)
{
//printf("[%s] escapeByRef, e: %s\n", e->loc->toChars(), e->toChars());
class EscapeRefVisitor : public Visitor
{
public:
EscapeByResults *er;
EscapeRefVisitor(EscapeByResults *er)
: er(er)
{
}
void visit(Expression *)
{
}
void visit(VarExp *e)
{
VarDeclaration *v = e->var->isVarDeclaration();
if (v)
{
if (v->storage_class & STCref && v->storage_class & (STCforeach | STCtemp) && v->_init)
{
/* If compiler generated ref temporary
* (ref v = ex; ex)
* look at the initializer instead
*/
if (ExpInitializer *ez = v->_init->isExpInitializer())
{
assert(ez->exp && ez->exp->op == TOKconstruct);
Expression *ex = ((ConstructExp *)ez->exp)->e2;
ex->accept(this);
}
}
else
er->byref.push(v);
}
}
void visit(ThisExp *e)
{
if (e->var)
er->byref.push(e->var);
}
void visit(PtrExp *e)
{
escapeByValue(e->e1, er);
}
void visit(IndexExp *e)
{
Type *tb = e->e1->type->toBasetype();
if (e->e1->op == TOKvar)
{
VarDeclaration *v = ((VarExp *)e->e1)->var->isVarDeclaration();
if (tb->ty == Tarray || tb->ty == Tsarray)
{
if (v->storage_class & STCvariadic)
{
er->byref.push(v);
return;
}
}
}
if (tb->ty == Tsarray)
{
e->e1->accept(this);
}
else if (tb->ty == Tarray)
{
escapeByValue(e->e1, er);
}
}
void visit(DotVarExp *e)
{
Type *t1b = e->e1->type->toBasetype();
if (t1b->ty == Tclass)
escapeByValue(e->e1, er);
else
e->e1->accept(this);
}
void visit(BinAssignExp *e)
{
e->e1->accept(this);
}
void visit(AssignExp *e)
{
e->e1->accept(this);
}
void visit(CommaExp *e)
{
e->e2->accept(this);
}
void visit(CondExp *e)
{
e->e1->accept(this);
e->e2->accept(this);
}
void visit(CallExp *e)
{
/* If the function returns by ref, check each argument that is
* passed as 'return ref'.
*/
Type *t1 = e->e1->type->toBasetype();
TypeFunction *tf;
if (t1->ty == Tdelegate)
tf = (TypeFunction *)((TypeDelegate *)t1)->next;
else if (t1->ty == Tfunction)
tf = (TypeFunction *)t1;
else
return;
if (tf->isref)
{
if (e->arguments && e->arguments->dim)
{
/* j=1 if _arguments[] is first argument,
* skip it because it is not passed by ref
*/
size_t j = (tf->linkage == LINKd && tf->varargs == 1);
for (size_t i = j; i < e->arguments->dim; ++i)
{
Expression *arg = (*e->arguments)[i];
size_t nparams = Parameter::dim(tf->parameters);
if (i - j < nparams && i >= j)
{
Parameter *p = Parameter::getNth(tf->parameters, i - j);
const StorageClass stc = tf->parameterStorageClass(p);
if ((stc & (STCout | STCref)) && (stc & STCreturn))
arg->accept(this);
else if ((stc & STCscope) && (stc & STCreturn))
{
if (arg->op == TOKdelegate)
{
DelegateExp *de = (DelegateExp *)arg;
if (de->func->isNested())
er->byexp.push(de);
}
else
escapeByValue(arg, er);
}
}
}
}
// If 'this' is returned by ref, check it too
if (e->e1->op == TOKdotvar && t1->ty == Tfunction)
{
DotVarExp *dve = (DotVarExp *)e->e1;
if (dve->var->storage_class & STCreturn || tf->isreturn)
{
if ((dve->var->storage_class & STCscope) || tf->isscope)
escapeByValue(dve->e1, er);
else if ((dve->var->storage_class & STCref) || tf->isref)
dve->e1->accept(this);
}
}
// If it's a delegate, check it too
if (e->e1->op == TOKvar && t1->ty == Tdelegate)
{
escapeByValue(e->e1, er);
}
}
else
er->byexp.push(e);
}
};
EscapeRefVisitor v(er);
e->accept(&v);
}
/*************************
* Find all variables accessed by this delegate that are
* in functions enclosing it.
* Params:
* fd = function
* vars = array to append found variables to
*/
void findAllOuterAccessedVariables(FuncDeclaration *fd, VarDeclarations *vars)
{
//printf("findAllOuterAccessedVariables(fd: %s)\n", fd.toChars());
for (Dsymbol *p = fd->parent; p; p = p->parent)
{
FuncDeclaration *fdp = p->isFuncDeclaration();
if (fdp)
{
for (size_t i = 0; i < fdp->closureVars.dim; i++)
{
VarDeclaration *v = fdp->closureVars[i];
for (size_t j = 0; j < v->nestedrefs.dim; j++)
{
FuncDeclaration *fdv = v->nestedrefs[j];
if (fdv == fd)
{
//printf("accessed: %s, type %s\n", v->toChars(), v->type->toChars());
vars->push(v);
}
}
}
}
}
}