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tgt-vvp: Fix store skip on real typed array entries 

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>
This commit is contained in:
Lars-Peter Clausen 2022-01-01 10:46:56 +01:00
parent 4c8903f117
commit b83ebf3c8e
1 changed files with 2 additions and 25 deletions
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27
tgt-vvp/stmt_assign.c
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@ -759,31 +759,8 @@ static void store_real_to_lval(ivl_lval_t lval)
ivl_expr_t word_ex = ivl_lval_idx(lval);
int word_ix = allocate_word();
/* If the word index is a constant, then we can write
directly to the word and save the index calculation.
Out-of-bounds and undefined indices are converted to
a canonical index of 'bx during elaboration, and we
don't try to optimise that case. */
if (word_ex && number_is_immediate(word_ex, IMM_WID, 0) &&
!number_is_unknown(word_ex)) {
unsigned long use_word = get_number_immediate(word_ex);
assert(use_word < ivl_signal_array_count(var));
fprintf(vvp_out, " %%ix/load %d, %lu, 0;\n",
word_ix, use_word);
fprintf(vvp_out, " %%store/reala v%p, %d;\n",
var, word_ix);
} else {
unsigned do_store = transient_id++;
unsigned end_store = transient_id++;
draw_eval_expr_into_integer(word_ex, word_ix);
fprintf(vvp_out, " %%jmp/0 t_%u, 4;\n", do_store);
fprintf(vvp_out, " %%pop/real 1;\n");
fprintf(vvp_out, " %%jmp t_%u;\n", end_store);
fprintf(vvp_out, "t_%u ;\n", do_store);
fprintf(vvp_out, " %%store/reala v%p, %d;\n", var, word_ix);
fprintf(vvp_out, "t_%u ;\n", end_store);
}
draw_eval_expr_into_integer(word_ex, word_ix);
fprintf(vvp_out, " %%store/reala v%p, %d;\n", var, word_ix);
clr_word(word_ix);
}