When unsized literals are used in case item expressions, it is likely
that the calculated expression width will be larger than necessary to
unambiguously select the correct case item (particularly when using
"strict" expression elaboration). This patch adds an optimisation
step that prunes the expressions to the minimum necessary width.
For shift operations evaluated at compile time, the compiler was converting
the right operand to a native unsigned long value. If the operand exceeded
the size of an unsigned long, excess bits were discarded, which could lead
to an incorrect result.
The fix I've chosen is to add an as_unsigned() function to the verinum class
which returns the maximum unsigned value if the internal verinum value is
wider than the native unsigned type. This then naturally gives the correct
result for shifts, as the verinum bit width is also an unsigned value.
I've changed the as_ulong() and as_ulong64() functions to do likewise, as
this is more likely to either give the correct behaviour or to give some
indication that an overflow has occurred where these functions are used.
The verinum arithmetic operators now observe the standard Verilog
rules for calculating the result width if all operands are sized.
If any operand is unsized, the result is lossless, as before.
They also now all observe the standard rules for handling partially
undefined operands (if any operand bit is 'x', the entire result is
'x').
I've also added the unary '-' operator, and renamed v_not() to be
the unary '~' operator. This has allowed some simplification in
other parts of the compiler.
This patch adds support for implicit casts to the elaborate_rval_expr()
function. This will handle the majority of cases where an implicit cast
can occur.
This patch covers more than it should. It removes many of the -Wextra
warnings in the main ivl directory. It also makes some minor code
improvements, adds support for constant logicals in eval_tree (&&/||),
adds support for correctly sign extending === and !==, it starts to
standardize the eval_tree debug messages and fixes a strength bug
in the target interface (found with -Wextra). The rest of the warnings
and eval_tree() rework will need to come as a second patch.
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.
When calculating 0^z with constant arguments, make sure the result is
x. This problem only happens when the arguments are constants and the
expression is calculated at compile time.
Problems with signed expressions that are set to parameters and
that include multipliciation exposed a few bugs in the calculation
of signed multiply. Fix this and add some improved diagnostics.
Martin Whitaker
Christian Taedcke
Cary R
Stephen Williams
Arun Persaud
Jared Casper
steve