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Merge pull request #187 from YosysHQ/fix_lock_passthru

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ice40: Fix LOCK feedthrough insertion with carry or >8 LUTs
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David Shah 2018-12-20 19:16:11 +00:00 committed by GitHub
commit 580f6fbd21
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1 changed files with 10 additions and 4 deletions
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14
ice40/pack.cc
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@ -1181,20 +1181,26 @@ static void pack_special(Context *ctx)
log_info(" PLL '%s' has LOCK output, need to pass all outputs via LUT\n", ci->name.c_str(ctx));
bool found_lut = false;
bool all_luts = true;
bool found_carry = false;
unsigned int lut_count = 0;
for (const auto &user : port.net->users) {
NPNR_ASSERT(user.cell != nullptr);
if (user.cell->type == ctx->id("ICESTORM_LC")) {
found_lut = true;
lut_count++;
if (bool_or_default(user.cell->params, ctx->id("CARRY_ENABLE"), false)) {
found_carry = true;
all_luts = false;
} else {
found_lut = true;
lut_count++;
}
} else {
all_luts = false;
}
}
if (found_lut && all_luts) {
if (found_lut && all_luts && lut_count < 8) {
// Every user is a LUT, carry on now.
} else if (found_lut && !all_luts && lut_count < 8) {
} else if (found_lut && !all_luts && !found_carry && lut_count < 8) {
// Strategy: create a pass-through LUT, move all non-LUT users behind it.
log_info(" LUT strategy for %s: move non-LUT users to new LUT\n", port.name.c_str(ctx));
auto pt = spliceLUT(ctx, packed.get(), port.name, true);