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authorClifford Wolf <clifford@clifford.at>2014-07-21 21:38:55 +0200
committerClifford Wolf <clifford@clifford.at>2014-07-21 21:38:55 +0200
commit137dbf3cf7edbec8c31dfdb2c9c0bcc413c5786d (patch)
treef69c5ca96e1b2ac86e0ce2328612f8de4e6879e7 /passes
parent1873480ca5f5ec9ec6aa1b80b91ae047a6982002 (diff)
Added "opt_const -keepdc"
Diffstat (limited to 'passes')
-rw-r--r--passes/opt/opt.cc13
-rw-r--r--passes/opt/opt_const.cc170
2 files changed, 168 insertions, 15 deletions
diff --git a/passes/opt/opt.cc b/passes/opt/opt.cc
index 62aa48be..33e1507b 100644
--- a/passes/opt/opt.cc
+++ b/passes/opt/opt.cc
@@ -31,7 +31,7 @@ struct OptPass : public Pass {
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
- log(" opt [-purge] [-mux_undef] [-mux_bool] [-undriven] [-fine] [selection]\n");
+ log(" opt [options] [selection]\n");
log("\n");
log("This pass calls all the other opt_* passes in a useful order. This performs\n");
log("a series of trivial optimizations and cleanups. This pass executes the other\n");
@@ -46,8 +46,11 @@ struct OptPass : public Pass {
log(" opt_share\n");
log(" opt_rmdff\n");
log(" opt_clean [-purge]\n");
- log(" opt_const [-mux_undef] [-mux_bool] [-undriven] [-fine]\n");
- log(" while [changed design]\n");
+ log(" opt_const [-mux_undef] [-mux_bool] [-undriven] [-fine] [-keepdc]\n");
+ log(" while <changed design>\n");
+ log("\n");
+ log("Note: Options in square brackets (such as [-keepdc]) are passed through to\n");
+ log("the opt_* commands when given to 'opt'.\n");
log("\n");
}
virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
@@ -82,6 +85,10 @@ struct OptPass : public Pass {
opt_reduce_args += " -fine";
continue;
}
+ if (args[argidx] == "-keepdc") {
+ opt_const_args += " -keepdc";
+ continue;
+ }
break;
}
extra_args(args, argidx, design);
diff --git a/passes/opt/opt_const.cc b/passes/opt/opt_const.cc
index 4cfee59d..e855e45e 100644
--- a/passes/opt/opt_const.cc
+++ b/passes/opt/opt_const.cc
@@ -74,6 +74,8 @@ static void replace_undriven(RTLIL::Design *design, RTLIL::Module *module)
static void replace_cell(RTLIL::Module *module, RTLIL::Cell *cell, std::string info, std::string out_port, RTLIL::SigSpec out_val)
{
RTLIL::SigSpec Y = cell->connections[out_port];
+ out_val.extend_u0(Y.width, false);
+
log("Replacing %s cell `%s' (%s) in module `%s' with constant driver `%s = %s'.\n",
cell->type.c_str(), cell->name.c_str(), info.c_str(),
module->name.c_str(), log_signal(Y), log_signal(out_val));
@@ -114,6 +116,12 @@ static bool group_cell_inputs(RTLIL::Module *module, RTLIL::Cell *cell, bool com
int group_idx = GRP_DYN;
RTLIL::SigBit bit_a = bits_a[i], bit_b = bits_b[i];
+ if (cell->type == "$or" && (bit_a == RTLIL::State::S1 || bit_b == RTLIL::State::S1))
+ bit_a = bit_b = RTLIL::State::S1;
+
+ if (cell->type == "$and" && (bit_a == RTLIL::State::S0 || bit_b == RTLIL::State::S0))
+ bit_a = bit_b = RTLIL::State::S0;
+
if (bit_a.wire == NULL && bit_b.wire == NULL)
group_idx = GRP_CONST_AB;
else if (bit_a.wire == NULL)
@@ -181,7 +189,7 @@ static bool group_cell_inputs(RTLIL::Module *module, RTLIL::Cell *cell, bool com
return true;
}
-static void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool consume_x, bool mux_undef, bool mux_bool, bool do_fine)
+static void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool consume_x, bool mux_undef, bool mux_bool, bool do_fine, bool keepdc)
{
if (!design->selected(module))
return;
@@ -204,10 +212,132 @@ static void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bo
#define ACTION_DO(_p_, _s_) do { replace_cell(module, cell, input.as_string(), _p_, _s_); goto next_cell; } while (0)
#define ACTION_DO_Y(_v_) ACTION_DO("\\Y", RTLIL::SigSpec(RTLIL::State::S ## _v_))
- if (do_fine && (cell->type == "$not" || cell->type == "$pos" || cell->type == "$bu0" ||
- cell->type == "$and" || cell->type == "$or" || cell->type == "$xor" || cell->type == "$xnor"))
- if (group_cell_inputs(module, cell, true, cell->type != "$pos", assign_map))
+ if (do_fine)
+ {
+ if (cell->type == "$not" || cell->type == "$pos" || cell->type == "$bu0" ||
+ cell->type == "$and" || cell->type == "$or" || cell->type == "$xor" || cell->type == "$xnor")
+ if (group_cell_inputs(module, cell, true, cell->type != "$pos", assign_map))
+ goto next_cell;
+
+ if (cell->type == "$reduce_and")
+ {
+ RTLIL::SigSpec sig_a = assign_map(cell->connections.at("\\A"));
+
+ RTLIL::State new_a = RTLIL::State::S1;
+ for (auto &bit : sig_a.to_sigbit_vector())
+ if (bit == RTLIL::State::Sx) {
+ if (new_a == RTLIL::State::S1)
+ new_a = RTLIL::State::Sx;
+ } else if (bit == RTLIL::State::S0) {
+ new_a = RTLIL::State::S0;
+ break;
+ } else if (bit.wire != NULL) {
+ new_a = RTLIL::State::Sm;
+ }
+
+ if (new_a != RTLIL::State::Sm && RTLIL::SigSpec(new_a) != sig_a) {
+ log("Replacing port A of %s cell `%s' in module `%s' with constant driver: %s -> %s\n",
+ cell->type.c_str(), cell->name.c_str(), module->name.c_str(), log_signal(sig_a), log_signal(new_a));
+ cell->connections.at("\\A") = sig_a = new_a;
+ cell->parameters.at("\\A_WIDTH") = 1;
+ OPT_DID_SOMETHING = true;
+ did_something = true;
+ }
+ }
+
+ if (cell->type == "$logic_not" || cell->type == "$logic_and" || cell->type == "$logic_or" || cell->type == "$reduce_or" || cell->type == "$reduce_bool")
+ {
+ RTLIL::SigSpec sig_a = assign_map(cell->connections.at("\\A"));
+
+ RTLIL::State new_a = RTLIL::State::S0;
+ for (auto &bit : sig_a.to_sigbit_vector())
+ if (bit == RTLIL::State::Sx) {
+ if (new_a == RTLIL::State::S0)
+ new_a = RTLIL::State::Sx;
+ } else if (bit == RTLIL::State::S1) {
+ new_a = RTLIL::State::S1;
+ break;
+ } else if (bit.wire != NULL) {
+ new_a = RTLIL::State::Sm;
+ }
+
+ if (new_a != RTLIL::State::Sm && RTLIL::SigSpec(new_a) != sig_a) {
+ log("Replacing port A of %s cell `%s' in module `%s' with constant driver: %s -> %s\n",
+ cell->type.c_str(), cell->name.c_str(), module->name.c_str(), log_signal(sig_a), log_signal(new_a));
+ cell->connections.at("\\A") = sig_a = new_a;
+ cell->parameters.at("\\A_WIDTH") = 1;
+ OPT_DID_SOMETHING = true;
+ did_something = true;
+ }
+ }
+
+ if (cell->type == "$logic_and" || cell->type == "$logic_or")
+ {
+ RTLIL::SigSpec sig_b = assign_map(cell->connections.at("\\B"));
+
+ RTLIL::State new_b = RTLIL::State::S0;
+ for (auto &bit : sig_b.to_sigbit_vector())
+ if (bit == RTLIL::State::Sx) {
+ if (new_b == RTLIL::State::S0)
+ new_b = RTLIL::State::Sx;
+ } else if (bit == RTLIL::State::S1) {
+ new_b = RTLIL::State::S1;
+ break;
+ } else if (bit.wire != NULL) {
+ new_b = RTLIL::State::Sm;
+ }
+
+ if (new_b != RTLIL::State::Sm && RTLIL::SigSpec(new_b) != sig_b) {
+ log("Replacing port B of %s cell `%s' in module `%s' with constant driver: %s -> %s\n",
+ cell->type.c_str(), cell->name.c_str(), module->name.c_str(), log_signal(sig_b), log_signal(new_b));
+ cell->connections.at("\\B") = sig_b = new_b;
+ cell->parameters.at("\\B_WIDTH") = 1;
+ OPT_DID_SOMETHING = true;
+ did_something = true;
+ }
+ }
+ }
+
+ if (cell->type == "$logic_or" && (assign_map(cell->connections.at("\\A")) == RTLIL::State::S1 || assign_map(cell->connections.at("\\B")) == RTLIL::State::S1)) {
+ replace_cell(module, cell, "one high", "\\Y", RTLIL::State::S1);
+ goto next_cell;
+ }
+
+ if (cell->type == "$logic_and" && (assign_map(cell->connections.at("\\A")) == RTLIL::State::S0 || assign_map(cell->connections.at("\\B")) == RTLIL::State::S0)) {
+ replace_cell(module, cell, "one low", "\\Y", RTLIL::State::S0);
+ goto next_cell;
+ }
+
+ if (cell->type == "$reduce_xor" || cell->type == "$reduce_xnor" ||
+ cell->type == "$shl" || cell->type == "$shr" || cell->type == "$sshl" || cell->type == "$sshr" ||
+ cell->type == "$lt" || cell->type == "$le" || cell->type == "$ge" || cell->type == "$gt" ||
+ cell->type == "$neg" || cell->type == "$add" || cell->type == "$sub" ||
+ cell->type == "$mul" || cell->type == "$div" || cell->type == "$mod" || cell->type == "$pow")
+ {
+ RTLIL::SigSpec sig_a = assign_map(cell->connections.at("\\A"));
+ RTLIL::SigSpec sig_b = cell->connections.count("\\B") ? assign_map(cell->connections.at("\\B")) : RTLIL::SigSpec();
+
+ if (cell->type == "$shl" || cell->type == "$shr" || cell->type == "$sshl" || cell->type == "$sshr")
+ sig_a = RTLIL::SigSpec();
+
+ for (auto &bit : sig_a.to_sigbit_vector())
+ if (bit == RTLIL::State::Sx)
+ goto found_the_x_bit;
+
+ for (auto &bit : sig_b.to_sigbit_vector())
+ if (bit == RTLIL::State::Sx)
+ goto found_the_x_bit;
+
+ if (0) {
+ found_the_x_bit:
+ if (cell->type == "$reduce_xor" || cell->type == "$reduce_xnor" ||
+ cell->type == "$lt" || cell->type == "$le" || cell->type == "$ge" || cell->type == "$gt")
+ replace_cell(module, cell, "x-bit in input", "\\Y", RTLIL::State::Sx);
+ else
+ replace_cell(module, cell, "x-bit in input", "\\Y", RTLIL::SigSpec(RTLIL::State::Sx, cell->connections.at("\\Y").width));
goto next_cell;
+ }
+ }
if ((cell->type == "$_INV_" || cell->type == "$not" || cell->type == "$logic_not") && cell->connections["\\Y"].width == 1 &&
invert_map.count(assign_map(cell->connections["\\A"])) != 0) {
@@ -389,7 +519,7 @@ static void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bo
}
}
- // checking for simple identities
+ if (!keepdc)
{
bool identity_bu0 = false;
bool identity_wrt_a = false;
@@ -647,7 +777,7 @@ static void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bo
ACTION_DO("\\Y", cell->connections["\\A"]);
}
- if (do_fine && cell->type == "$mul")
+ if (!keepdc && cell->type == "$mul")
{
bool a_signed = cell->parameters["\\A_SIGNED"].as_bool();
bool b_signed = cell->parameters["\\B_SIGNED"].as_bool();
@@ -677,22 +807,27 @@ static void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bo
goto next_cell;
}
- for (int i = 0; i < sig_a.width - (a_signed ? 1 : 0); i++)
+ for (int i = 1; i < (a_signed ? sig_a.width-1 : sig_a.width); i++)
if (a_val == (1 << i))
{
log("Replacing multiply-by-%d cell `%s' in module `%s' with shift-by-%d.\n",
a_val, cell->name.c_str(), module->name.c_str(), i);
- if (swapped_ab) {
+ if (!swapped_ab) {
cell->connections["\\A"] = cell->connections["\\B"];
cell->parameters["\\A_WIDTH"] = cell->parameters["\\B_WIDTH"];
cell->parameters["\\A_SIGNED"] = cell->parameters["\\B_SIGNED"];
}
+ std::vector<RTLIL::SigBit> new_b = RTLIL::SigSpec(i, 6);
+
+ while (SIZE(new_b) > 1 && new_b.back() == RTLIL::State::S0)
+ new_b.pop_back();
+
cell->type = "$shl";
- cell->parameters["\\B_WIDTH"] = 6;
+ cell->parameters["\\B_WIDTH"] = SIZE(new_b);
cell->parameters["\\B_SIGNED"] = false;
- cell->connections["\\B"] = RTLIL::SigSpec(i, 6);
+ cell->connections["\\B"] = new_b;
cell->check();
OPT_DID_SOMETHING = true;
@@ -729,6 +864,12 @@ struct OptConstPass : public Pass {
log(" -undriven\n");
log(" replace undriven nets with undef (x) constants\n");
log("\n");
+ log(" -keepdc\n");
+ log(" some optimizations change the behavior of the circuit with respect to\n");
+ log(" don't-care bits. for example in 'a+0' a single x-bit in 'a' will cause\n");
+ log(" all result bits to be set to x. this behavior changes when 'a+0' is\n");
+ log(" replaced by 'a'. the -keepdc option disables all such optimizations.\n");
+ log("\n");
log(" -fine\n");
log(" perform fine-grain optimizations\n");
log("\n");
@@ -739,6 +880,7 @@ struct OptConstPass : public Pass {
bool mux_bool = false;
bool undriven = false;
bool do_fine = false;
+ bool keepdc = false;
log_header("Executing OPT_CONST pass (perform const folding).\n");
log_push();
@@ -761,6 +903,10 @@ struct OptConstPass : public Pass {
do_fine = true;
continue;
}
+ if (args[argidx] == "-keepdc") {
+ keepdc = true;
+ continue;
+ }
break;
}
extra_args(args, argidx, design);
@@ -773,9 +919,9 @@ struct OptConstPass : public Pass {
do {
do {
did_something = false;
- replace_const_cells(design, mod_it.second, false, mux_undef, mux_bool, do_fine);
+ replace_const_cells(design, mod_it.second, false, mux_undef, mux_bool, do_fine, keepdc);
} while (did_something);
- replace_const_cells(design, mod_it.second, true, mux_undef, mux_bool, do_fine);
+ replace_const_cells(design, mod_it.second, true, mux_undef, mux_bool, do_fine, keepdc);
} while (did_something);
}