Currently nested lvalues are only supported for vector typed properties.
Refactor the code to also support other types.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Currently assignment operators on queues and dynamic elements trigger an
assert.
Add support for handling this properly. Since the operation for loading an
element for an queue or dynamic array is identical most of the code can be
shared, only writing back the value has to be handled separately.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Currently assignment operators on object properties are silently
ignored. Make sure that they are handled.
To enable this refactor the code a bit so that the assignment
operator handling can be shared between object property assignments
and scalar value assignments.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Remove implicit casts between vector and real in tgt-vvp. These are not
required since any implicit cast in the source will be converted to an
explicit cast in the elaboration stage.
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>
SystemVerilog allows to use assignment patterns to assign values to an
array. E.g. `int a[4] = '{1, 2, 3, 4}`.
Each value is evaluated in the context of the element type of the array.
Nested assignment patterns are supported. E.g. `int a[2][2] = '{'{1, 2},
'{1, 2}};`
Add initial support for array assignment patterns for both continuous as
well as procedural assignments.
For continuous assignments the assignment pattern is synthesized into an
array of nets. Each pin is connected to one of the assignment pattern
values and then the whole net array is connected to target array.
For procedural assignments it is unrolled in the vvp backend. E.g
effectively turning `a = '{1, 2};` into `a[0] = 1; a[1] = 2;`.
Not yet supported are indexed initializers or `default`.
E.g. `int a[10] = '{1:10, default: 20};`
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
There are some cases where during an assignment the elaboration step can
generate constructs with the right-hand-side expression being wider than
the left-hand-side expression.
To handle this the tgt-vvp backend inserts a %pad operation when necessary.
One place where this is missing is when writing to an string element. Here
instead an assert is triggered requiring the right-hand-side expression to
be 8 bits wide.
E.g.
```
bit [7:0] x;
bit [8:0] y;
string s;
x = y; // tgt-vvp inserts %pad
s[0] = y; // tgt-vvp triggers assert
```
Long term this should be fixed at the elaboration stage and insert the
proper width cast. But for now solve this the same way as other places in
tgt-vvp and insert the %pad operation for string element assignments if the
width does not match.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
The C++ API for `ivl_type_t` has a method to query the total width of a
packed type. This is currently not exported to the C API and the tgt-vvp
backend implements similar functionality by querying the individual
dimensions of a type.
Export the `packed_width()` method to the C API. This allows to remove the
custom implementation from the tgt-vvp backend.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
The basic structure for supporting assignment operators on real arrays
exists in the tgt-vvp backend. But there are a few problems, most
importantly it generates the wrong instruction for loading data from the
real array.
The instruction it uses is `%load/reala`, but that instruction does not
exist, the correct name is `%load/ar`.
In addition to this there are a few minor problems.
* Out-of-bounds access on the array triggers an assert
* Missing `%pop/real` instruction when skipping a write due to
out-of-bounds access
Address these so assignment operators are supported on real array entries.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
For an out-of-bounds assignment operator on an array element an assert is
hit if the element width is great than 32.
Remove the assert and make sure that this case is handled correctly by
using the `%pad/s` instruction to extended the X value to the correct
width.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
If the index of an array access is known to be out-of-bounds during
elaboration it is replaced with 'x. In the tgt-vvp backend that is handling
compressed array assignments there is an assert() that triggers if the
index is an undefined immediate.
There is already an existing code path that is capable of handling
out-of-bounds access. Remove the assert and set the index to ULONG_MAX to
trigger taking the out-of-bound access path.
On this out-of-bounds path the write to the array is skipped. But this
leaves the result on the vector stack. Insert the `%pop/vec4` instruction
to make sure it is removed.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
The operator assignment on dynamic part selects uses the `%store/vec4`
instruction to store the value. This instruction will skip the assignment
if flag 4 is set. This is for handling the case where the index is
undefined.
Since the left hand side of the assignment is an arbitrary expression it
can change the flag. The implementation handles this by making a copy of
the flag and restoring it before executing the `%store/vec4` instruction.
The flag is set by the `%ix/vec4` instruction when loading the index
register. But the copy of the flag is made before that and just picks
up the flag that was stored by previous expressions. This can cause
the store to be skipped when it shouldn't.
E.g. in the following code the increment will be skipped. Flag 4 is used
from the `a == 0` comparison, rather than from computing the part select
index.
```
int a = 0;
if (a == 0) begin
a[a+:2] += 1;
end
$display(a); // Will print 0, should print 1
```
Fix this by moving the copy of the flag after the `%ix/vec4` instruction.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
The vvp `%load/vec4a` instruction will skip the load if vvp flag 4 is set
and return 'x. This is meant for handling the case where the index is
undefined.
For assignment operators on array entries, when the index is an immediate
value, vvp flag 4 is not cleared before the load instruction. If a previous
instruction set flag 4 it load yield 'x.
E.g. for the following sequence `x[0]` should be `11`, but will be `'x`.
```
integer x[10];
logic a = 1'b0;
x[0] = 10;
if (a == 0) begin
x[0] += 1;
end
```
Properly clear the flag before the load instruction to handle this
correctly.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
When assigning a value to a real typed array entry the vvp `%store/reala`
instruction. This instruction will skip the store if the vvp flag 4 is set.
This is to handle the case where the index is undefined.
When the index into the array is an immediate value the flag 4 is not
cleared. If a previous instruction set flag 4 the store will be skipped.
E.g. for the following r[0] will remain 0.0 since the assignment to it is
skipped.
```
integer a = 0;
real r[1:0];
if (a == 0) begin
r[0] = 1.23;
end
```
Fix this by using the `draw_eval_expr_into_integer()` helper function to
evaluate the index into a word register. The function correctly handles all
the special cases.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
There is currently a restriction in the vvp code generator backend that
throws an assertion when generating wire access for a multi-dimensional
real array.
But there is nothing special about multi-dimensional arrays. In vvp arrays
are in canonical form. Meaning they only have a single dimension and the
conversion form multi to single dimension is done in the higher layers.
Remove the assert to allow multi-dimensional real arrays.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
The `%store/dar/...` and `%store/qdar/...` instructions are used to load a
value into an entry in dynamic array or queue. These instructions will skip
the load if VVP flag 4 is 1.
For assignment pattern initialization these instructions are used to load
the value of the individual assignment pattern expressions into the dynamic
array.
For queues flag 4 is never cleared when generating the code for the
assignment pattern. This means the initialization might be skipped
depending on what value the flag had before.
```
int a = 1;
int q[$];
a = a == 1;
q = {1, 2, 3, 4};
```
For dynamic arrays it is cleared once in the beginning. But each item in
the assignment pattern can be an arbitrary expression. Evaluating the
expression can cause the flag to get overwritten. E.g. the following code
will skip the assignments.
```
int a = 1;
int d[];
d = {a ? 1 : 1, 2, 3, 4};
```
To fix these issues make sure that the flag is cleared after evaluating
each initialization expression and before executing the `%store/...`
instruction.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
IEEE Std 1800-2017 Section 7.6 Array assignments
Assignment of a dynamic array creates a duplicate of the source,
so that assignments to the copy don't impact the original. Handle
all sorts of dynamic array base types.
When -pfileline=1 is used the queue procedural warnings have file
and line information added to the messages. Also switch the trace
debugging to be off by default.
Also, Add some preliminary missing darray functionality.
As discussed on iverilog-devel (2018-03-09), the existing implementation
(using Icarus-specific vpi functions) only worked with assignments to
simple variables, and could not be easily modified to work more generally.
So use the new vvp instructions added in the previous two commits.
The .scope needs to be aware of return types so that the %call/vec4
function knows how to intialize the return value. We also need to
extend the %ret/vec4 to support writing parts of the return value.
Defining __USE_MINGW_ANSI_STDIO=1 provides C99 compatible printf
and scanf routines, which avoids the need for workarounds for the
various failings of the Microsoft C runtime library.
Cary R
Lars-Peter Clausen
Stephen Williams
Martin Whitaker
Martin Whitaker
Maciej Suminski