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Fix casts to integer types. 

Casting from signed to unsigned types and vice versa is legal in SV,
as is casting from a larger to a smaller size. Obey Verilog rules
for expression bit width and signedness.
This commit is contained in:
Martin Whitaker 2019-10-10 23:48:11 +01:00
parent 1a40a6f902
commit d56e90c3f4
1 changed files with 56 additions and 51 deletions
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107
elab_expr.cc
View File

@ -2752,8 +2752,8 @@ NetExpr* PECastSize::elaborate_expr(Design*des, NetScope*scope,
ivl_assert(*this, size_);
ivl_assert(*this, base_);
// When changing size, a cast behaves exactly like an assignment,
// so the result size affects the final expression width.
// A cast behaves exactly like an assignment to a temporary variable,
// so the temporary result size may affect the sub-expression width.
unsigned cast_width = base_->expr_width();
if (cast_width < expr_width_)
cast_width = expr_width_;
@ -2769,33 +2769,33 @@ NetExpr* PECastSize::elaborate_expr(Design*des, NetScope*scope,
return pad_to_width(tmp, expr_wid, signed_flag_, *this);
}
unsigned PECastType::test_width(Design*des, NetScope*scope, width_mode_t&wid)
unsigned PECastType::test_width(Design*des, NetScope*scope, width_mode_t&)
{
ivl_type_t t = target_->elaborate_type(des, scope);
base_->test_width(des, scope, wid);
if(const netdarray_t*use_darray = dynamic_cast<const netdarray_t*> (t)) {
width_mode_t tmp_mode = PExpr::SIZED;
base_->test_width(des, scope, tmp_mode);
if (const netdarray_t*use_darray = dynamic_cast<const netdarray_t*>(t)) {
expr_type_ = use_darray->element_base_type();
expr_width_ = use_darray->element_width();
}
else if(const netstring_t*use_string = dynamic_cast<const netstring_t*> (t)) {
} else if (const netstring_t*use_string = dynamic_cast<const netstring_t*>(t)) {
expr_type_ = use_string->base_type();
expr_width_ = 8;
}
else {
} else {
expr_type_ = t->base_type();
expr_width_ = t->packed_width();
}
min_width_ = expr_width_;
signed_flag_ = t->get_signed();
min_width_ = expr_width_;
return expr_width_;
}
NetExpr* PECastType::elaborate_expr(Design*des, NetScope*scope,
ivl_type_t type, unsigned) const
ivl_type_t type, unsigned flags) const
{
const netdarray_t*darray = NULL;
const netvector_t*vector = NULL;
@ -2824,57 +2824,62 @@ NetExpr* PECastType::elaborate_expr(Design*des, NetScope*scope,
}
// Fallback
return elaborate_expr(des, scope, (unsigned) 0, 0);
return elaborate_expr(des, scope, (unsigned) 0, flags);
}
NetExpr* PECastType::elaborate_expr(Design*des, NetScope*scope,
unsigned, unsigned) const
unsigned expr_wid, unsigned flags) const
{
NetExpr*expr = base_->elaborate_expr(des, scope, base_->expr_width(), NO_FLAGS);
flags &= ~SYS_TASK_ARG; // don't propagate the SYS_TASK_ARG flag
if(dynamic_cast<const real_type_t*>(target_)) {
return cast_to_real(expr);
// A cast behaves exactly like an assignment to a temporary variable,
// so the temporary result size may affect the sub-expression width.
unsigned cast_width = base_->expr_width();
if (type_is_vectorable(base_->expr_type()) && (cast_width < expr_width_))
cast_width = expr_width_;
NetExpr*sub = base_->elaborate_expr(des, scope, cast_width, flags);
if (dynamic_cast<const real_type_t*>(target_)) {
return cast_to_real(sub);
}
if(const atom2_type_t*atom = dynamic_cast<const atom2_type_t*>(target_)) {
if(base_->expr_width() > expr_width_) {
cerr << get_fileline() << ": cast type is not wide enough to store the result." << endl;
ivl_assert(*this, 0);
}
NetExpr*tmp = 0;
if (dynamic_cast<const atom2_type_t*>(target_)) {
tmp = cast_to_int2(sub, expr_width_);
}
if (const vector_type_t*vec = dynamic_cast<const vector_type_t*>(target_)) {
switch (vec->base_type) {
case IVL_VT_BOOL:
tmp = cast_to_int2(sub, expr_width_);
break;
if(base_->has_sign() != atom->signed_flag) {
cerr << get_fileline() << ": cast type and subject differ in signedness." << endl;
ivl_assert(*this, 0);
}
case IVL_VT_LOGIC:
tmp = cast_to_int4(sub, expr_width_);
break;
// That is how you both resize & cast to integers
return new NetECast('2', expr, expr_width_, expr->has_sign());
default:
break;
}
}
if (tmp) {
if (tmp == sub) {
// We already had the correct base type, so we just need to
// fix the size. Note that even if the size is already correct,
// we still need to isolate the sub-expression from changes in
// the signedness pushed down from the main expression.
tmp = cast_to_width(sub, expr_width_, sub->has_sign(), *this);
}
return pad_to_width(tmp, expr_wid, signed_flag_, *this);
}
if(const vector_type_t*vec = dynamic_cast<const vector_type_t*>(target_)) {
switch(vec->base_type) {
case IVL_VT_BOOL:
return cast_to_int2(expr, expr_width_);
if (dynamic_cast<const string_type_t*>(target_)) {
if (base_->expr_type() == IVL_VT_STRING)
return sub; // no conversion
case IVL_VT_LOGIC:
return cast_to_int4(expr, expr_width_);
default:
break; /* Suppress warnings */
}
}
else if(dynamic_cast<const string_type_t*>(target_)) {
if(base_->expr_type() == IVL_VT_STRING)
return expr; // no conversion
if((base_->expr_type() != IVL_VT_BOOL) &&
(base_->expr_type() != IVL_VT_LOGIC)) {
cerr << get_fileline() << ": cannot be cast to a string." << endl;
ivl_assert(*this, false);
}
return expr;
if (base_->expr_type() == IVL_VT_LOGIC
|| base_->expr_type() == IVL_VT_BOOL)
return sub; // handled by the target as special cases
}
cerr << get_fileline() << ": sorry: This cast operation is not yet supported." << endl;