/
optimize.c
1182 lines (1044 loc) · 32 KB
/
optimize.c
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// Compiler implementation of the D programming language
// Copyright (c) 1999-2012 by Digital Mars
// All Rights Reserved
// written by Walter Bright
// http://www.digitalmars.com
// License for redistribution is by either the Artistic License
// in artistic.txt, or the GNU General Public License in gnu.txt.
// See the included readme.txt for details.
#include <stdio.h>
#include <ctype.h>
#include <assert.h>
#include <math.h>
#if __DMC__
#include <complex.h>
#endif
#include "lexer.h"
#include "mtype.h"
#include "expression.h"
#include "declaration.h"
#include "aggregate.h"
#include "init.h"
#ifdef IN_GCC
#include "d-gcc-real.h"
/* %% fix? */
extern "C" bool real_isnan (const real_t *);
#endif
static real_t zero; // work around DMC bug for now
/*************************************
* If variable has a const initializer,
* return that initializer.
*/
Expression *expandVar(int result, VarDeclaration *v)
{
//printf("expandVar(result = %d, v = %p, %s)\n", result, v, v ? v->toChars() : "null");
Expression *e = NULL;
if (!v)
return e;
if (!v->originalType && v->scope) // semantic() not yet run
v->semantic (v->scope);
if (v->isConst() || v->isImmutable() || v->storage_class & STCmanifest)
{
if (!v->type)
{
//error("ICE");
return e;
}
Type *tb = v->type->toBasetype();
if (result & WANTinterpret ||
v->storage_class & STCmanifest ||
v->type->toBasetype()->isscalar() ||
((result & WANTexpand) && (tb->ty != Tsarray && tb->ty != Tstruct))
)
{
if (v->init)
{
if (v->inuse)
{ if (v->storage_class & STCmanifest)
v->error("recursive initialization of constant");
goto L1;
}
Expression *ei = v->init->toExpression();
if (!ei)
{ if (v->storage_class & STCmanifest)
v->error("enum cannot be initialized with %s", v->init->toChars());
goto L1;
}
if (ei->op == TOKconstruct || ei->op == TOKblit)
{ AssignExp *ae = (AssignExp *)ei;
ei = ae->e2;
if (result & WANTinterpret)
{
v->inuse++;
ei = ei->optimize(result);
v->inuse--;
}
else if (ei->isConst() != 1 && ei->op != TOKstring)
goto L1;
if (ei->type == v->type)
{ // const variable initialized with const expression
}
else if (ei->implicitConvTo(v->type) >= MATCHconst)
{ // const var initialized with non-const expression
ei = ei->implicitCastTo(0, v->type);
ei = ei->semantic(0);
}
else
goto L1;
}
if (v->scope)
{
v->inuse++;
e = ei->syntaxCopy();
e = e->semantic(v->scope);
e = e->implicitCastTo(v->scope, v->type);
// enabling this line causes test22 in test suite to fail
//ei->type = e->type;
v->scope = NULL;
v->inuse--;
}
else if (!ei->type)
{
goto L1;
}
else
// Should remove the copy() operation by
// making all mods to expressions copy-on-write
e = ei->copy();
}
else
{
#if 1
goto L1;
#else
// BUG: what if const is initialized in constructor?
e = v->type->defaultInit();
e->loc = e1->loc;
#endif
}
if (e->type != v->type)
{
e = e->castTo(NULL, v->type);
}
v->inuse++;
e = e->optimize(result);
v->inuse--;
}
}
L1:
//if (e) printf("\te = %p, %s, e->type = %d, %s\n", e, e->toChars(), e->type->ty, e->type->toChars());
return e;
}
Expression *fromConstInitializer(int result, Expression *e1)
{
//printf("fromConstInitializer(result = %x, %s)\n", result, e1->toChars());
//static int xx; if (xx++ == 10) assert(0);
Expression *e = e1;
if (e1->op == TOKvar)
{ VarExp *ve = (VarExp *)e1;
VarDeclaration *v = ve->var->isVarDeclaration();
e = expandVar(result, v);
if (e)
{
// If it is a comma expression involving a declaration, we mustn't
// perform a copy -- we'd get two declarations of the same variable.
// See bugzilla 4465.
if (e->op == TOKcomma && ((CommaExp *)e)->e1->op == TOKdeclaration)
e = e1;
else
if (e->type != e1->type && e1->type && e1->type->ty != Tident)
{ // Type 'paint' operation
e = e->copy();
e->type = e1->type;
}
e->loc = e1->loc;
}
else
{
e = e1;
/* If we needed to interpret, generate an error.
* Don't give an error if it's a template parameter
*/
if (v && (result & WANTinterpret) &&
!(v->storage_class & STCtemplateparameter))
{
e1->error("variable %s cannot be read at compile time", v->toChars());
e->type = Type::terror;
}
}
}
return e;
}
Expression *Expression::optimize(int result)
{
//printf("Expression::optimize(result = x%x) %s\n", result, toChars());
return this;
}
Expression *VarExp::optimize(int result)
{
return fromConstInitializer(result, this);
}
Expression *TupleExp::optimize(int result)
{
for (size_t i = 0; i < exps->dim; i++)
{ Expression *e = (*exps)[i];
e = e->optimize(WANTvalue | (result & WANTinterpret));
(*exps)[i] = e;
}
return this;
}
Expression *ArrayLiteralExp::optimize(int result)
{
if (elements)
{
for (size_t i = 0; i < elements->dim; i++)
{ Expression *e = (*elements)[i];
e = e->optimize(WANTvalue | (result & (WANTinterpret | WANTexpand)));
(*elements)[i] = e;
}
}
return this;
}
Expression *AssocArrayLiteralExp::optimize(int result)
{
assert(keys->dim == values->dim);
for (size_t i = 0; i < keys->dim; i++)
{ Expression *e = (*keys)[i];
e = e->optimize(WANTvalue | (result & (WANTinterpret | WANTexpand)));
(*keys)[i] = e;
e = (*values)[i];
e = e->optimize(WANTvalue | (result & (WANTinterpret | WANTexpand)));
(*values)[i] = e;
}
return this;
}
Expression *StructLiteralExp::optimize(int result)
{
if (elements)
{
for (size_t i = 0; i < elements->dim; i++)
{ Expression *e = (*elements)[i];
if (!e)
continue;
e = e->optimize(WANTvalue | (result & (WANTinterpret | WANTexpand)));
(*elements)[i] = e;
}
}
return this;
}
Expression *TypeExp::optimize(int result)
{
return this;
}
Expression *UnaExp::optimize(int result)
{
//printf("UnaExp::optimize() %s\n", toChars());
e1 = e1->optimize(result);
return this;
}
Expression *NegExp::optimize(int result)
{ Expression *e;
e1 = e1->optimize(result);
if (e1->isConst() == 1)
{
e = Neg(type, e1);
}
else
e = this;
return e;
}
Expression *ComExp::optimize(int result)
{ Expression *e;
e1 = e1->optimize(result);
if (e1->isConst() == 1)
{
e = Com(type, e1);
}
else
e = this;
return e;
}
Expression *NotExp::optimize(int result)
{ Expression *e;
e1 = e1->optimize(result);
if (e1->isConst() == 1)
{
e = Not(type, e1);
}
else
e = this;
return e;
}
Expression *BoolExp::optimize(int result)
{ Expression *e;
e1 = e1->optimize(result);
if (e1->isConst() == 1)
{
e = Bool(type, e1);
}
else
e = this;
return e;
}
Expression *AddrExp::optimize(int result)
{ Expression *e;
//printf("AddrExp::optimize(result = %d) %s\n", result, toChars());
/* Rewrite &(a,b) as (a,&b)
*/
if (e1->op == TOKcomma)
{ CommaExp *ce = (CommaExp *)e1;
AddrExp *ae = new AddrExp(loc, ce->e2);
ae->type = type;
e = new CommaExp(ce->loc, ce->e1, ae);
e->type = type;
return e->optimize(result);
}
if (e1->op == TOKvar)
{ VarExp *ve = (VarExp *)e1;
if (ve->var->storage_class & STCmanifest)
e1 = e1->optimize(result);
}
else
e1 = e1->optimize(result);
// Convert &*ex to ex
if (e1->op == TOKstar)
{ Expression *ex;
ex = ((PtrExp *)e1)->e1;
if (type->equals(ex->type))
e = ex;
else
{
e = ex->copy();
e->type = type;
}
return e;
}
if (e1->op == TOKvar)
{ VarExp *ve = (VarExp *)e1;
if (!ve->var->isOut() && !ve->var->isRef() &&
!ve->var->isImportedSymbol())
{
SymOffExp *se = new SymOffExp(loc, ve->var, 0, ve->hasOverloads);
se->type = type;
return se;
}
}
if (e1->op == TOKindex)
{ // Convert &array[n] to &array+n
IndexExp *ae = (IndexExp *)e1;
if (ae->e2->op == TOKint64 && ae->e1->op == TOKvar)
{
dinteger_t index = ae->e2->toInteger();
VarExp *ve = (VarExp *)ae->e1;
if (ve->type->ty == Tsarray
&& !ve->var->isImportedSymbol())
{
TypeSArray *ts = (TypeSArray *)ve->type;
dinteger_t dim = ts->dim->toInteger();
if (index < 0 || index >= dim)
error("array index %lld is out of bounds [0..%lld]", index, dim);
e = new SymOffExp(loc, ve->var, index * ts->nextOf()->size());
e->type = type;
return e;
}
}
}
return this;
}
Expression *PtrExp::optimize(int result)
{
//printf("PtrExp::optimize(result = x%x) %s\n", result, toChars());
e1 = e1->optimize(result);
// Convert *&ex to ex
if (e1->op == TOKaddress)
{ Expression *e;
Expression *ex;
ex = ((AddrExp *)e1)->e1;
if (type->equals(ex->type))
e = ex;
else
{
e = ex->copy();
e->type = type;
}
return e;
}
// Constant fold *(&structliteral + offset)
if (e1->op == TOKadd)
{
Expression *e;
e = Ptr(type, e1);
if (e != EXP_CANT_INTERPRET)
return e;
}
if (e1->op == TOKsymoff)
{ SymOffExp *se = (SymOffExp *)e1;
VarDeclaration *v = se->var->isVarDeclaration();
Expression *e = expandVar(result, v);
if (e && e->op == TOKstructliteral)
{ StructLiteralExp *sle = (StructLiteralExp *)e;
e = sle->getField(type, se->offset);
if (e && e != EXP_CANT_INTERPRET)
return e;
}
}
return this;
}
Expression *DotVarExp::optimize(int result)
{
//printf("DotVarExp::optimize(result = x%x) %s\n", result, toChars());
e1 = e1->optimize(result);
Expression *e = e1;
if (e1->op == TOKvar)
{ VarExp *ve = (VarExp *)e1;
VarDeclaration *v = ve->var->isVarDeclaration();
e = expandVar(result, v);
}
if (e && e->op == TOKstructliteral)
{ StructLiteralExp *sle = (StructLiteralExp *)e;
VarDeclaration *vf = var->isVarDeclaration();
if (vf)
{
Expression *e = sle->getField(type, vf->offset);
if (e && e != EXP_CANT_INTERPRET)
return e;
}
}
return this;
}
Expression *NewExp::optimize(int result)
{
if (thisexp)
thisexp = thisexp->optimize(WANTvalue);
// Optimize parameters
if (newargs)
{
for (size_t i = 0; i < newargs->dim; i++)
{ Expression *e = (*newargs)[i];
e = e->optimize(WANTvalue);
(*newargs)[i] = e;
}
}
if (arguments)
{
for (size_t i = 0; i < arguments->dim; i++)
{ Expression *e = (*arguments)[i];
e = e->optimize(WANTvalue);
(*arguments)[i] = e;
}
}
if (result & WANTinterpret)
{
error("cannot evaluate %s at compile time", toChars());
}
return this;
}
Expression *CallExp::optimize(int result)
{
//printf("CallExp::optimize(result = %d) %s\n", result, toChars());
Expression *e = this;
// Optimize parameters
if (arguments)
{
for (size_t i = 0; i < arguments->dim; i++)
{ Expression *e = (*arguments)[i];
e = e->optimize(WANTvalue);
(*arguments)[i] = e;
}
}
e1 = e1->optimize(result);
#if 1
if (result & WANTinterpret)
{
Expression *eresult = interpret(NULL);
if (eresult == EXP_CANT_INTERPRET)
return e;
if (eresult && eresult != EXP_VOID_INTERPRET)
e = eresult;
else
error("cannot evaluate %s at compile time", toChars());
}
#else
if (e1->op == TOKvar)
{
FuncDeclaration *fd = ((VarExp *)e1)->var->isFuncDeclaration();
if (fd)
{
enum BUILTIN b = fd->isBuiltin();
if (b)
{
e = eval_builtin(b, arguments);
if (!e) // failed
e = this; // evaluate at runtime
}
else if (result & WANTinterpret)
{
Expression *eresult = fd->interpret(NULL, arguments);
if (eresult && eresult != EXP_VOID_INTERPRET)
e = eresult;
else
error("cannot evaluate %s at compile time", toChars());
}
}
}
else if (e1->op == TOKdotvar && result & WANTinterpret)
{ DotVarExp *dve = (DotVarExp *)e1;
FuncDeclaration *fd = dve->var->isFuncDeclaration();
if (fd)
{
Expression *eresult = fd->interpret(NULL, arguments, dve->e1);
if (eresult && eresult != EXP_VOID_INTERPRET)
e = eresult;
else
error("cannot evaluate %s at compile time", toChars());
}
}
#endif
return e;
}
Expression *CastExp::optimize(int result)
{
//printf("CastExp::optimize(result = %d) %s\n", result, toChars());
//printf("from %s to %s\n", type->toChars(), to->toChars());
//printf("from %s\n", type->toChars());
//printf("e1->type %s\n", e1->type->toChars());
//printf("type = %p\n", type);
assert(type);
enum TOK op1 = e1->op;
#define X 0
Expression *e1old = e1;
e1 = e1->optimize(result);
e1 = fromConstInitializer(result, e1);
if (e1 == e1old &&
e1->op == TOKarrayliteral &&
type->toBasetype()->ty == Tpointer &&
e1->type->toBasetype()->ty != Tsarray)
{
// Casting this will result in the same expression, and
// infinite loop because of Expression::implicitCastTo()
return this; // no change
}
if ((e1->op == TOKstring || e1->op == TOKarrayliteral) &&
(type->ty == Tpointer || type->ty == Tarray) &&
e1->type->nextOf()->size() == type->nextOf()->size()
)
{
Expression *e = e1->castTo(NULL, type);
if (X) printf(" returning1 %s\n", e->toChars());
return e;
}
if (e1->op == TOKstructliteral &&
e1->type->implicitConvTo(type) >= MATCHconst)
{
e1->type = type;
if (X) printf(" returning2 %s\n", e1->toChars());
return e1;
}
/* The first test here is to prevent infinite loops
*/
if (op1 != TOKarrayliteral && e1->op == TOKarrayliteral)
return e1->castTo(NULL, to);
if (e1->op == TOKnull &&
(type->ty == Tpointer || type->ty == Tclass || type->ty == Tarray))
{
e1->type = type;
if (X) printf(" returning3 %s\n", e1->toChars());
return e1;
}
if (result & WANTflags && type->ty == Tclass && e1->type->ty == Tclass)
{
// See if we can remove an unnecessary cast
ClassDeclaration *cdfrom;
ClassDeclaration *cdto;
int offset;
cdfrom = e1->type->isClassHandle();
cdto = type->isClassHandle();
if (cdto->isBaseOf(cdfrom, &offset) && offset == 0)
{
e1->type = type;
if (X) printf(" returning4 %s\n", e1->toChars());
return e1;
}
}
// We can convert 'head const' to mutable
if (to->mutableOf()->constOf()->equals(e1->type->mutableOf()->constOf()))
{
e1->type = type;
if (X) printf(" returning5 %s\n", e1->toChars());
return e1;
}
Expression *e;
if (e1->isConst())
{
if (e1->op == TOKsymoff)
{
if (type->size() == e1->type->size() &&
type->toBasetype()->ty != Tsarray)
{
e1->type = type;
return e1;
}
return this;
}
if (to->toBasetype()->ty == Tvoid)
e = this;
else
e = Cast(type, to, e1);
}
else
e = this;
if (X) printf(" returning6 %s\n", e->toChars());
return e;
#undef X
}
Expression *BinExp::optimize(int result)
{
//printf("BinExp::optimize(result = %d) %s\n", result, toChars());
if (op != TOKconstruct && op != TOKblit) // don't replace const variable with its initializer
e1 = e1->optimize(result);
e2 = e2->optimize(result);
if (op == TOKshlass || op == TOKshrass || op == TOKushrass)
{
if (e2->isConst() == 1)
{
dinteger_t i2 = e2->toInteger();
d_uns64 sz = e1->type->size() * 8;
if (i2 < 0 || i2 >= sz)
{ error("shift assign by %lld is outside the range 0..%llu", i2, (ulonglong)sz - 1);
e2 = new IntegerExp(0);
}
}
}
return this;
}
Expression *AddExp::optimize(int result)
{ Expression *e;
//printf("AddExp::optimize(%s)\n", toChars());
e1 = e1->optimize(result);
e2 = e2->optimize(result);
if (e1->isConst() && e2->isConst())
{
if (e1->op == TOKsymoff && e2->op == TOKsymoff)
return this;
e = Add(type, e1, e2);
}
else
e = this;
return e;
}
Expression *MinExp::optimize(int result)
{ Expression *e;
e1 = e1->optimize(result);
e2 = e2->optimize(result);
if (e1->isConst() && e2->isConst())
{
if (e2->op == TOKsymoff)
return this;
e = Min(type, e1, e2);
}
else
e = this;
return e;
}
Expression *MulExp::optimize(int result)
{ Expression *e;
//printf("MulExp::optimize(result = %d) %s\n", result, toChars());
e1 = e1->optimize(result);
e2 = e2->optimize(result);
if (e1->isConst() == 1 && e2->isConst() == 1)
{
e = Mul(type, e1, e2);
}
else
e = this;
return e;
}
Expression *DivExp::optimize(int result)
{ Expression *e;
//printf("DivExp::optimize(%s)\n", toChars());
e1 = e1->optimize(result);
e2 = e2->optimize(result);
if (e1->isConst() == 1 && e2->isConst() == 1)
{
e = Div(type, e1, e2);
}
else
e = this;
return e;
}
Expression *ModExp::optimize(int result)
{ Expression *e;
e1 = e1->optimize(result);
e2 = e2->optimize(result);
if (e1->isConst() == 1 && e2->isConst() == 1)
{
e = Mod(type, e1, e2);
}
else
e = this;
return e;
}
Expression *shift_optimize(int result, BinExp *e, Expression *(*shift)(Type *, Expression *, Expression *))
{ Expression *ex = e;
e->e1 = e->e1->optimize(result);
e->e2 = e->e2->optimize(result);
if (e->e2->isConst() == 1)
{
dinteger_t i2 = e->e2->toInteger();
d_uns64 sz = e->e1->type->size() * 8;
if (i2 < 0 || i2 >= sz)
{ e->error("shift by %lld is outside the range 0..%llu", i2, (ulonglong)sz - 1);
e->e2 = new IntegerExp(0);
}
if (e->e1->isConst() == 1)
ex = (*shift)(e->type, e->e1, e->e2);
}
return ex;
}
Expression *ShlExp::optimize(int result)
{
//printf("ShlExp::optimize(result = %d) %s\n", result, toChars());
return shift_optimize(result, this, Shl);
}
Expression *ShrExp::optimize(int result)
{
//printf("ShrExp::optimize(result = %d) %s\n", result, toChars());
return shift_optimize(result, this, Shr);
}
Expression *UshrExp::optimize(int result)
{
//printf("UshrExp::optimize(result = %d) %s\n", result, toChars());
return shift_optimize(result, this, Ushr);
}
Expression *AndExp::optimize(int result)
{ Expression *e;
e1 = e1->optimize(result);
e2 = e2->optimize(result);
if (e1->isConst() == 1 && e2->isConst() == 1)
e = And(type, e1, e2);
else
e = this;
return e;
}
Expression *OrExp::optimize(int result)
{ Expression *e;
e1 = e1->optimize(result);
e2 = e2->optimize(result);
if (e1->isConst() == 1 && e2->isConst() == 1)
e = Or(type, e1, e2);
else
e = this;
return e;
}
Expression *XorExp::optimize(int result)
{ Expression *e;
e1 = e1->optimize(result);
e2 = e2->optimize(result);
if (e1->isConst() == 1 && e2->isConst() == 1)
e = Xor(type, e1, e2);
else
e = this;
return e;
}
Expression *PowExp::optimize(int result)
{ Expression *e;
e1 = e1->optimize(result);
e2 = e2->optimize(result);
// Replace 1 ^^ x or 1.0^^x by (x, 1)
if ((e1->op == TOKint64 && e1->toInteger() == 1) ||
(e1->op == TOKfloat64 && e1->toReal() == 1.0))
{
e = new CommaExp(loc, e2, e1);
}
// Replace -1 ^^ x by (x&1) ? -1 : 1, where x is integral
else if (e2->type->isintegral() && e1->op == TOKint64 && (sinteger_t)e1->toInteger() == -1L)
{
Type* resultType = type;
e = new AndExp(loc, e2, new IntegerExp(loc, 1, e2->type));
e = new CondExp(loc, e, new IntegerExp(loc, -1L, resultType), new IntegerExp(loc, 1L, resultType));
}
// Replace x ^^ 0 or x^^0.0 by (x, 1)
else if ((e2->op == TOKint64 && e2->toInteger() == 0) ||
(e2->op == TOKfloat64 && e2->toReal() == 0.0))
{
if (e1->type->isintegral())
e = new IntegerExp(loc, 1, e1->type);
else
e = new RealExp(loc, ldouble(1.0), e1->type);
e = new CommaExp(loc, e1, e);
}
// Replace x ^^ 1 or x^^1.0 by (x)
else if ((e2->op == TOKint64 && e2->toInteger() == 1) ||
(e2->op == TOKfloat64 && e2->toReal() == 1.0))
{
e = e1;
}
// Replace x ^^ -1.0 by (1.0 / x)
else if ((e2->op == TOKfloat64 && e2->toReal() == -1.0))
{
e = new DivExp(loc, new RealExp(loc, ldouble(1.0), e2->type), e1);
}
// All other negative integral powers are illegal
else if ((e1->type->isintegral()) && (e2->op == TOKint64) && (sinteger_t)e2->toInteger() < 0)
{
error("cannot raise %s to a negative integer power. Did you mean (cast(real)%s)^^%s ?",
e1->type->toBasetype()->toChars(), e1->toChars(), e2->toChars());
e = new ErrorExp();
}
else
{
// If e2 *could* have been an integer, make it one.
if (e2->op == TOKfloat64 && (e2->toReal() == (sinteger_t)(e2->toReal())))
e2 = new IntegerExp(loc, e2->toInteger(), Type::tint64);
if (e1->isConst() == 1 && e2->isConst() == 1)
{
e = Pow(type, e1, e2);
if (e != EXP_CANT_INTERPRET)
return e;
}
e = this;
}
return e;
}
Expression *CommaExp::optimize(int result)
{ Expression *e;
//printf("CommaExp::optimize(result = %d) %s\n", result, toChars());
// Comma needs special treatment, because it may
// contain compiler-generated declarations. We can interpret them, but
// otherwise we must NOT attempt to constant-fold them.
// In particular, if the comma returns a temporary variable, it needs
// to be an lvalue (this is particularly important for struct constructors)
if (result & WANTinterpret)
{ // Interpreting comma needs special treatment, because it may
// contain compiler-generated declarations.
e = interpret(NULL);
return (e == EXP_CANT_INTERPRET) ? this : e;
}
e1 = e1->optimize(result & WANTinterpret);
e2 = e2->optimize(result);
if (!e1 || e1->op == TOKint64 || e1->op == TOKfloat64 || !e1->hasSideEffect())
{
e = e2;
if (e)
e->type = type;
}
else
e = this;
//printf("-CommaExp::optimize(result = %d) %s\n", result, e->toChars());
return e;
}
Expression *ArrayLengthExp::optimize(int result)
{ Expression *e;
//printf("ArrayLengthExp::optimize(result = %d) %s\n", result, toChars());
e1 = e1->optimize(WANTvalue | WANTexpand | (result & WANTinterpret));
e = this;
if (e1->op == TOKstring || e1->op == TOKarrayliteral || e1->op == TOKassocarrayliteral)
{
e = ArrayLength(type, e1);
}
return e;
}
Expression *EqualExp::optimize(int result)
{ Expression *e;
//printf("EqualExp::optimize(result = %x) %s\n", result, toChars());
e1 = e1->optimize(WANTvalue | (result & WANTinterpret));
e2 = e2->optimize(WANTvalue | (result & WANTinterpret));
e = this;
Expression *e1 = fromConstInitializer(result, this->e1);
Expression *e2 = fromConstInitializer(result, this->e2);
e = Equal(op, type, e1, e2);
if (e == EXP_CANT_INTERPRET)
e = this;
return e;
}
Expression *IdentityExp::optimize(int result)
{
//printf("IdentityExp::optimize(result = %d) %s\n", result, toChars());
e1 = e1->optimize(WANTvalue | (result & WANTinterpret));
e2 = e2->optimize(WANTvalue | (result & WANTinterpret));
Expression *e = this;
if ((this->e1->isConst() && this->e2->isConst()) ||
(this->e1->op == TOKnull && this->e2->op == TOKnull))
{
e = Identity(op, type, this->e1, this->e2);
if (e == EXP_CANT_INTERPRET)
e = this;
}
return e;
}
/* It is possible for constant folding to change an array expression of
* unknown length, into one where the length is known.
* If the expression 'arr' is a literal, set lengthVar to be its length.
*/
void setLengthVarIfKnown(VarDeclaration *lengthVar, Expression *arr)
{
if (!lengthVar)
return;
if (lengthVar->init && !lengthVar->init->isVoidInitializer())
return; // we have previously calculated the length
size_t len;
if (arr->op == TOKstring)
len = ((StringExp *)arr)->len;
else if (arr->op == TOKarrayliteral)
len = ((ArrayLiteralExp *)arr)->elements->dim;
else
return; // we don't know the length yet