The vlog95 code generator collects all the constant assignments to a net
within each scope and then emits them. The old code only recorded the
ivl_signal_t for each constant assignment, which meant it had to iterate
through the nexus pointers in the assicated nexus to find the constant.
When there were multiple constant assignments to the same net, it needed
to record which assignments had already been emitted, which it did by
keeping a count in the nexus private data and skipping that many constants
on each successive assignment. However the count did not get reset after
emitting all the assignments in that scope, so if there were assignments
to the same net made in another scope, the count would already be positive
and those assignments would also be skipped.
This could probably have been fixed by clearing the nexus private data
after processing the constant assignment list for each scope, but it is
more efficient to record the ivl_nexus_ptr_t for each constant along with
the ivl_signal_t, eliminating the need to search for the associated nexus
pointer.
Internally, the maximum address space of a vector is 31 bits + a sign bit
to signal invalid addresses (out of bounds or has one or more x or z bits).
This commit ensures that unsigned part-select bit addresses which would
otherwise overflow and wrap around within this address space are correctly
handled as out of bounds.
The for loop initialisation statement, termination condition, and step
statement were only made optional in IEEE 1800-2012. Commit 0695c1fe
enforced this. So we need to compile with -g2012. The vlog95 code
generator doesn't currently translate this, so the tests will fail
when compiling the translated code.
Early editions of the SystemVerilog standard did not specify the return
type for $bits, so we made it 32 bit unsigned 2-state. Later editions
state the return type is integer (32 bit signed 4-state), so make it so.
When multiple words in one array were connected to the same nexus as a
single word array, the code generator was sometimes failing to generate
all the necessary aliases. This was highly dependent on the elaboration
order.
This fix should be more robust, but there are currently no tests in the
test suite that cause the compiler to generate whole-array aliases, and
I can't think of a way to make it do so as we don't yet support unpacked
arrays in module ports, so that branch of the code is currently untested.
Add a regression test to check that the right-hand side of a shift
operation is always treated as unsigned, even if it is a signed registers
or a variation thereof.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
When loading a signal into into an index register currently the signedness
of the signal is used when deciding whether sign-extension should be
performed or not. But this can lead to incorrect results, instead the
signedness of the expression must be used as that might be different from
the signal. E.g.
```
reg signed [1:0] = 2'b10;
$display(1 << x[1:0]);
```
gives the wrong result without this.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Check that assignments with undefined intra-assignment delay get executed
with zero delay. The assignment should not be skipped.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Assignments with an undefined intra-assignment delay should be treated like
assignments with zero delay. For the most part this is implemented
correctly, except for assignments to a part of a vector where the offset
inside the vector is an immediate value. E.g.
```
reg [1:0] x;
integer d = 'x;
...
x[0] <= #d 1'b1
```
Here when loading the delay into the index register flag 4 is updated, but
never cleared afterwards. As a result, if the delay is undefined, the vector
assignment will be skipped. Fix this by making sure flag 4 is always
cleared before the vector assignment instruction.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
For sequences where the tgt-vvp backend generates `%pushi` followed by one
of the operations that have an immediate version replace it with the
immediate version. This is slightly more efficient.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
As discussed in issue #1143, the for loop initialisation statement,
termination condition, and step statement were only made optional in
IEEE 1800-2012. So check all three are present when compiling for
ealier generations.
SystemVerilog makes all of the initialisation, condition, and step
components of a for loop optional. We already support this for the
initialisation and step components.
A constant function call may be inside a named block, so we need to
search upwards to find the enclosing module before checking that the
called function is local to that module.
SystemVerilog allows constant function calls to reference functions
in (other) packages or in the $unit scope, so extend the checks to
permit that.
Update the versions of called Actions to prevent warnings.hi and add
"workflow_dispatch" to allow testing.
Unrelated: add "*.so" to .gitignore to hide built libvvp.so.
The tran island resolution tests and caches the state of all branch
enable inputs before resolving the branch endpoint values. If a
branch enable is connected directly to a branch endpoint, we need
to update the cached stete and rerun the island resolution if any
enable state changed.
This fixes issue #1122.
Martin Whitaker
Cary R
Lars-Peter Clausen
henry
Dag Lem
ga