This patch changes the method used to signal that a constant expression
is being elaborated from flags stored in global variables to flags
passed down the call chain. It also generates more informative error
messages when variable references are found in a constant expression.
Currently the compiler coerces input ports to inout ports whenever
there is an internal driver connected to the internal port net.
This generates an error if the port is externally connected to
something other than a structural net. This patch modifies the
compiler to ensure port coercion only occurs in valid cases.
This patch ensures that the result of a shift is an undefined value
if the right operand is an undefined value. It also improves the
code generated for right shifts where the right operand is constant
and optimises away shifts where the right operand is a constant 0.
It also fixes a few places where the expression type (signed/unsigned)
was not being set correctly.
I'm adding more uses of the make_range_from_width function, so
it seems like time to get rid of its use of the svector template.
This thread led to a lot of other uses of svector that had to
also be removed.
Comparison expressions have sorta-self-determined arguments.
Handle the special cause that some of the arguments may be
themselves unsized, and so expecting to be even wider then
otherwise.
This is part of the 1800-2009 standard (Section 23.3.2.3) and allows
ports of module instances to be declared like:
modname instance(.foo, .bar);
instead of
modname instead(.foo(foo), .bar(bar));
The only tricky part about this is the implicit port connection shall
not create an implicit net declaration. To make this happen, the path
of least resistance was to add a bool to PEIdent indicating that it
should not implicitely create a net.
This does not rely on the generation flag to be 2009, following the
trend that new port naming convention (like ANSI style ports) work
regardless of the generation.
When handling the $signed/$unsigned system functions, the compiler
was applying the new signed/unsigned property to the NetExpr object
representing the input argument. This caused the input argument to
be evaluated incorrectly. This patch fixes this by applying the new
property to the NetExpr object created to pad the result to the
required size.
In testing this fix, it was also discovered that the width of the
input argument expression was not being calculated correctly. This
patch also fixes this issue.
Creation of implicit nets requires knowledge of whether an identifier
has been declared before it is used. Currently implicit nets are
created during elaboration, but by this stage the order of declaration
and use is not known. This patch moves the creation of implicit nets
into the parser stage.
Under some situation the optimized repeat expression can get out
of sync while it is being processed this causes the code to
reference freed memory. This happens when the repeat expression
is converted to an unsigned integer, but the repeat expression
is used in a different path. It was easier to just remove the
optimization then track down the convoluted call sequence that
was causing this and then figure out what needed to be fixed.
The repeat expression must be constant, so is likely not too
complicated so this optimization is very minor and should not
be missed.
This patch is a major rewrite of the indexed part selects (+: and -:).
It made the following enhancements:
1. Make indexed part selects work correctly with both big and little
endian vectors.
2. Add a warning flag that warns about constant out of bounds/or 'bx
indexed selects.
3. Moved the -: parameter code to its own routine.
4. Added support for straddling before part selects in a CA.
5. Added more assert(! number_is_unknown) statements.
6. Add warning for &PV<> select with a signed index signal that is
less than the width of an int. This will be fixed later.
7. Add support for loading a 'bx/'bz constant into a numeric register.
8. Add a number of signed value fixes to the compiler/code generator.
9. Major fix of draw_select_expr() in the code generator.
The test_width for repeat-concatenations is tricky because it
requires the evaluated value for the repeat expression. It should
be OK to call elab_and_eval on that expression even during the
test_width for the containing expression. We'll see.
Part selects need to be fully defined. If not, then the resulting
expression is 'bx no matter what. The same for bit selects, when
the bit select expression is constant.
This fixes up the elaboration of binary expressions found in
parameter expressions. Parameter expressions are special because
they elaborate early, before all the other parameters are necessarily
completed.
The power (**) and shift operators are different from other binary
operators because their expression width calculations rely only on
their left operand, with their right operand self-determined. Get
the handling of these operators out of the PEBinary base class to
prevent confusion.
This patch adds a number of compile and run-time checks for illegal
uses of variables declared in automatic tasks and functions. It
also adds a check for event expressions in automatic tasks that use
features not yet supported in VVP.
The natures of disciplines were already available, this just brings
the information forward to the ivl_target.h API and exposes them via
access functions.
The arguments of logical and/or are self determined, and the width is
fixed as 1 bit. Account for this special behavior by creating the
PEBLogic class.
The comparison operator operands are self determined, but are forced
to be the width of the wider operand. This means that the operands must
be evaluated with their widths truncated. In spite of all this, note
that comparisons expression results are 1 bit wide.
The condition expression needs its width tested, even if the width
is not used. Also clean up some handling of widths/types for other
expression types.
If either of the operands of a ternary expression are unsigned, then
both are treated as unsigned. It works just like a binary expression
in that regard.
Later passes need the intermediate results for width and size so that
some special cases, were self-determined arguments occur, can be
processed properly during elaboration. This can be especially tricky
and interesting for ternary expressions.
This patch removes all the checks for constant expressions performed
during the parsing phase, as these checks are (mostly) repeated during
elaboration. It adds the missing check in the elaboration phase (the
RHS of a register initialisation), and improves the error reporting
and error recovery in other checks.
This patch fixes pr2132552, which was caused by a fault in the parser
constant expression checking.
The arguments to user defined functions are self-determined. And if
the result is real valued, we can call them lossless self-determined.
Treat these arguments like r-value elaboration for assignments.
Also clean up the binary divide elaboration a little bit.
Also, floating point literals are unsized with width==1.
the PGAssign elaborate method used the test_width to get the width
of the r-value expression. This should be completely sufficient to
get the width of the expression, so always use a defined width to
elaborate the expression.
When the condition expression of a ternary is constant 1 or 0, we can
short-circuit the elaboration by only processing the clause (true or
false) that we need. This saves compile time and execution time.
The expr:::synthesize methods need not deal with saturating left or
right shifts if they are dealt with early, in elaborate_expr methods.
So the elaborate_expr for shift takes on much more responsibility.
This patch adds the $clog2 system function. It also makes this
function work as a constant function. The runtime version still
needs to be updated to use an integer based version instead of
the current double based method. The double method suffers from
rounding errors.
Martin Whitaker
Cary R
Stephen Williams
Jared Casper
Martin Whitaker
Larry Doolittle