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Merge pull request #949 from YosysHQ/clifford/pmux2shimprove 

Add full_pmux feature to pmux2shiftx
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Clifford Wolf 2019-04-22 20:01:43 +02:00 committed by GitHub
parent 3be5aac52c a80e74dc20
commit 1d538ff1ec
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 24 additions and 3 deletions
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23
passes/opt/pmux2shiftx.cc
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@ -369,6 +369,7 @@ struct Pmux2ShiftxPass : public Pass {
dict<SigSpec, pool<int>> seldb;
SigSpec A = cell->getPort("\\A");
SigSpec B = cell->getPort("\\B");
SigSpec S = sigmap(cell->getPort("\\S"));
for (int i = 0; i < GetSize(S); i++)
@ -419,6 +420,8 @@ struct Pmux2ShiftxPass : public Pass {
choices[val] = i;
}
bool full_pmux = GetSize(choices) == GetSize(S);
// TBD: also find choices that are using signals that are subsets of the bits in "sig"
if (!verbose)
@ -634,7 +637,21 @@ struct Pmux2ShiftxPass : public Pass {
log(" range density: %d%%\n", range_density);
log(" absolute density: %d%%\n", absolute_density);
bool full_case = (min_choice == 0) && (max_choice == (1 << GetSize(sig))-1) && (max_choice+1 == GetSize(choices));
if (full_pmux) {
int full_density = 100*GetSize(choices) / (1 << GetSize(sig));
log(" full density: %d%%\n", full_density);
if (full_density < min_density) {
full_pmux = false;
} else {
min_choice = 0;
max_choice = (1 << GetSize(sig))-1;
log(" update to full case.\n");
log(" new min choice: %d\n", min_choice);
log(" new max choice: %d\n", max_choice);
}
}
bool full_case = (min_choice == 0) && (max_choice == (1 << GetSize(sig))-1) && (full_pmux || max_choice+1 == GetSize(choices));
log(" full case: %s\n", full_case ? "true" : "false");
// check density percentages
@ -677,6 +694,10 @@ struct Pmux2ShiftxPass : public Pass {
// create data signal
SigSpec data(State::Sx, (max_choice+1)*extwidth);
if (full_pmux) {
for (int i = 0; i <= max_choice; i++)
data.replace(i*extwidth, A);
}
for (auto &it : perm_choices) {
int position = it.first.as_int()*extwidth;
int data_index = it.second;

4
tests/various/pmux2shiftx.ys
View File

@ -9,8 +9,8 @@ opt
stat
# show -width
select -assert-count 1 t:$sub
select -assert-count 2 t:$mux
select -assert-count 2 t:$shift
select -assert-count 1 t:$mux
select -assert-count 1 t:$shift
select -assert-count 3 t:$shiftx
design -stash gate