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synth_xilinx: Use opt_dff.

The main part is converting xilinx_dsp to recognize the new FF types
created in opt_dff instead of trying to recognize the patterns on its
own.

The fsm call has been moved upwards because the passes cannot deal with
$dffe/$sdff*, and other optimizations don't help it much anyway.
This commit is contained in:
Marcelina Kościelnicka 2020-07-22 12:27:15 +02:00
parent 4a05cad7f8
commit 8501342fc5
7 changed files with 219 additions and 887 deletions

View file

@ -4,8 +4,6 @@
// At a high level, it works as follows:
// ( 1) Starting from a DSP48A/DSP48A1 cell
// ( 2) Match the driver of the 'B' input to a possible $dff cell (B1REG)
// (attached to at most two $mux cells that implement clock-enable or
// reset functionality, using a subpattern discussed below)
// If B1REG matched, treat 'B' input as input of B1REG
// ( 3) Match the driver of the 'B' and 'D' inputs for a possible $add cell
// (pre-adder)
@ -40,20 +38,15 @@ pattern xilinx_dsp48a_pack
state <SigBit> clock
state <SigSpec> sigA sigB sigC sigD sigM sigP
state <IdString> postAddAB postAddMuxAB
state <bool> ffAcepol ffBcepol ffDcepol ffMcepol ffPcepol
state <bool> ffArstpol ffBrstpol ffDrstpol ffMrstpol ffPrstpol
state <Cell*> ffA0 ffA0cemux ffA0rstmux ffA1 ffA1cemux ffA1rstmux
state <Cell*> ffB0 ffB0cemux ffB0rstmux ffB1 ffB1cemux ffB1rstmux
state <Cell*> ffD ffDcemux ffDrstmux ffM ffMcemux ffMrstmux ffP ffPcemux ffPrstmux
state <Cell*> ffA0 ffA1
state <Cell*> ffB0 ffB1
state <Cell*> ffD ffM ffP
// Variables used for subpatterns
state <SigSpec> argQ argD
state <bool> ffcepol ffrstpol
state <int> ffoffset
udata <SigSpec> dffD dffQ
udata <SigBit> dffclock
udata <Cell*> dff dffcemux dffrstmux
udata <bool> dffcepol dffrstpol
udata <Cell*> dff
// (1) Starting from a DSP48A/DSP48A1 cell
match dsp
@ -98,21 +91,13 @@ endcode
// (attached to at most two $mux cells that implement clock-enable or
// reset functionality, using a subpattern discussed above)
// If matched, treat 'B' input as input of B1REG
code argQ ffB1 ffB1cemux ffB1rstmux ffBcepol ffBrstpol sigB clock
code argQ ffB1 sigB clock
if (param(dsp, \B1REG).as_int() == 0 && param(dsp, \B0REG).as_int() == 0 && port(dsp, \OPMODE, SigSpec()).extract(4, 1).is_fully_zero()) {
argQ = sigB;
subpattern(in_dffe);
if (dff) {
ffB1 = dff;
clock = dffclock;
if (dffrstmux) {
ffB1rstmux = dffrstmux;
ffBrstpol = dffrstpol;
}
if (dffcemux) {
ffB1cemux = dffcemux;
ffBcepol = dffcepol;
}
sigB = dffD;
}
}
@ -147,41 +132,29 @@ code sigB sigD
endcode
// (4) Match 'B' input for B0REG
code argQ ffB0 ffB0cemux ffB0rstmux ffBcepol ffBrstpol sigB clock
code argQ ffB0 sigB clock
if (param(dsp, \B0REG).as_int() == 0) {
argQ = sigB;
subpattern(in_dffe);
if (dff) {
if (ffB1) {
if ((ffB1rstmux != nullptr) ^ (dffrstmux != nullptr))
if (dff->type != ffB1->type)
goto ffB0_end;
if ((ffB1cemux != nullptr) ^ (dffcemux != nullptr))
goto ffB0_end;
if (dffrstmux) {
if (ffBrstpol != dffrstpol)
if (dff->type.in($sdff, $sdffe, $sdffce)) {
if (param(dff, \SRST_POLARITY) != param(ffB1, \SRST_POLARITY))
goto ffB0_end;
if (port(ffB1rstmux, \S) != port(dffrstmux, \S))
if (port(dff, \SRST) != port(ffB1, \SRST))
goto ffB0_end;
ffB0rstmux = dffrstmux;
}
if (dffcemux) {
if (ffBcepol != dffcepol)
if (dff->type.in($dffe, $sdffe, $sdffce)) {
if (param(dff, \EN_POLARITY) != param(ffB1, \EN_POLARITY))
goto ffB0_end;
if (port(ffB1cemux, \S) != port(dffcemux, \S))
if (port(dff, \EN) != port(ffB1, \EN))
goto ffB0_end;
ffB0cemux = dffcemux;
}
}
ffB0 = dff;
clock = dffclock;
if (dffrstmux) {
ffB0rstmux = dffrstmux;
ffBrstpol = dffrstpol;
}
if (dffcemux) {
ffB0cemux = dffcemux;
ffBcepol = dffcepol;
}
sigB = dffD;
}
}
@ -190,21 +163,13 @@ endcode
// (5) Match 'A' input for A1REG
// If A1REG, then match 'A' input for A0REG
code argQ ffA1 ffA1cemux ffA1rstmux ffAcepol ffArstpol sigA clock ffA0 ffA0cemux ffA0rstmux
code argQ ffA1 sigA clock ffA0
if (param(dsp, \A0REG).as_int() == 0 && param(dsp, \A1REG).as_int() == 0) {
argQ = sigA;
subpattern(in_dffe);
if (dff) {
ffA1 = dff;
clock = dffclock;
if (dffrstmux) {
ffA1rstmux = dffrstmux;
ffArstpol = dffrstpol;
}
if (dffcemux) {
ffA1cemux = dffcemux;
ffAcepol = dffcepol;
}
sigA = dffD;
// Now attempt to match A0
@ -212,32 +177,23 @@ code argQ ffA1 ffA1cemux ffA1rstmux ffAcepol ffArstpol sigA clock ffA0 ffA0cemux
argQ = sigA;
subpattern(in_dffe);
if (dff) {
if ((ffA1rstmux != nullptr) ^ (dffrstmux != nullptr))
if (dff->type != ffA1->type)
goto ffA0_end;
if ((ffA1cemux != nullptr) ^ (dffcemux != nullptr))
goto ffA0_end;
if (dffrstmux) {
if (ffArstpol != dffrstpol)
if (dff->type.in($sdff, $sdffe, $sdffce)) {
if (param(dff, \SRST_POLARITY) != param(ffA1, \SRST_POLARITY))
goto ffA0_end;
if (port(ffA1rstmux, \S) != port(dffrstmux, \S))
if (port(dff, \SRST) != port(ffA1, \SRST))
goto ffA0_end;
ffA0rstmux = dffrstmux;
}
if (dffcemux) {
if (ffAcepol != dffcepol)
if (dff->type.in($dffe, $sdffe, $sdffce)) {
if (param(dff, \EN_POLARITY) != param(ffA1, \EN_POLARITY))
goto ffA0_end;
if (port(ffA1cemux, \S) != port(dffcemux, \S))
if (port(dff, \EN) != port(ffA1, \EN))
goto ffA0_end;
ffA0cemux = dffcemux;
}
ffA0 = dff;
clock = dffclock;
if (dffcemux) {
ffA0cemux = dffcemux;
ffAcepol = dffcepol;
}
sigA = dffD;
ffA0_end: ;
@ -249,42 +205,26 @@ ffA0_end: ;
endcode
// (6) Match 'D' input for DREG
code argQ ffD ffDcemux ffDrstmux ffDcepol ffDrstpol sigD clock
code argQ ffD sigD clock
if (param(dsp, \DREG).as_int() == 0) {
argQ = sigD;
subpattern(in_dffe);
if (dff) {
ffD = dff;
clock = dffclock;
if (dffrstmux) {
ffDrstmux = dffrstmux;
ffDrstpol = dffrstpol;
}
if (dffcemux) {
ffDcemux = dffcemux;
ffDcepol = dffcepol;
}
sigD = dffD;
}
}
endcode
// (7) Match 'P' output that exclusively drives an MREG
code argD ffM ffMcemux ffMrstmux ffMcepol ffMrstpol sigM sigP clock
code argD ffM sigM sigP clock
if (param(dsp, \MREG).as_int() == 0 && nusers(sigM) == 2) {
argD = sigM;
subpattern(out_dffe);
if (dff) {
ffM = dff;
clock = dffclock;
if (dffrstmux) {
ffMrstmux = dffrstmux;
ffMrstpol = dffrstpol;
}
if (dffcemux) {
ffMcemux = dffcemux;
ffMcepol = dffcepol;
}
sigM = dffQ;
}
}
@ -303,9 +243,7 @@ match postAdd
select postAdd->type.in($add)
select GetSize(port(postAdd, \Y)) <= 48
choice <IdString> AB {\A, \B}
select nusers(port(postAdd, AB)) <= 3
filter ffMcemux || nusers(port(postAdd, AB)) == 2
filter !ffMcemux || nusers(port(postAdd, AB)) == 3
select nusers(port(postAdd, AB)) == 2
index <SigBit> port(postAdd, AB)[0] === sigP[0]
filter GetSize(port(postAdd, AB)) >= GetSize(sigP)
@ -325,25 +263,14 @@ code sigC sigP
endcode
// (9) Match 'P' output that exclusively drives a PREG
code argD ffP ffPcemux ffPrstmux ffPcepol ffPrstpol sigP clock
code argD ffP sigP clock
if (param(dsp, \PREG).as_int() == 0) {
int users = 2;
// If ffMcemux and no postAdd new-value net must have three users: ffMcemux, ffM and ffPcemux
if (ffMcemux && !postAdd) users++;
if (nusers(sigP) == users) {
if (nusers(sigP) == 2) {
argD = sigP;
subpattern(out_dffe);
if (dff) {
ffP = dff;
clock = dffclock;
if (dffrstmux) {
ffPrstmux = dffrstmux;
ffPrstpol = dffrstpol;
}
if (dffcemux) {
ffPcemux = dffcemux;
ffPcepol = dffcepol;
}
sigP = dffQ;
}
}
@ -387,26 +314,13 @@ endcode
// #######################
// Subpattern for matching against input registers, based on knowledge of the
// 'Q' input. Typically, identifying registers with clock-enable and reset
// capability would be a task would be handled by other Yosys passes such as
// dff2dffe, but since DSP inference happens much before this, these patterns
// have to be manually identified.
// At a high level:
// (1) Starting from a $dff cell that (partially or fully) drives the given
// 'Q' argument
// (2) Match for a $mux cell implementing synchronous reset semantics ---
// one that exclusively drives the 'D' input of the $dff, with one of its
// $mux inputs being fully zero
// (3) Match for a $mux cell implement clock enable semantics --- one that
// exclusively drives the 'D' input of the $dff (or the other input of
// the reset $mux) and where one of this $mux's inputs is connected to
// the 'Q' output of the $dff
// 'Q' input.
subpattern in_dffe
arg argD argQ clock
arg argQ clock
code
dff = nullptr;
if (GetSize(argQ) == 0)
if (argQ.empty())
reject;
for (const auto &c : argQ.chunks()) {
// Abandon matches when 'Q' is a constant
@ -425,13 +339,14 @@ code
}
endcode
// (1) Starting from a $dff cell that (partially or fully) drives the given
// 'Q' argument
match ff
select ff->type.in($dff)
select ff->type.in($dff, $dffe, $sdff, $sdffe)
// DSP48E1 does not support clock inversion
select param(ff, \CLK_POLARITY).as_bool()
// Check that reset value, if present, is fully 0.
filter ff->type.in($dff, $dffe) || param(ff, \SRST_VALUE).is_fully_zero()
slice offset GetSize(port(ff, \D))
index <SigBit> port(ff, \Q)[offset] === argQ[0]
@ -440,82 +355,16 @@ match ff
filter port(ff, \Q).extract(offset, GetSize(argQ)) == argQ
filter clock == SigBit() || port(ff, \CLK) == clock
set ffoffset offset
endmatch
code argQ argD
code argQ
SigSpec Q = port(ff, \Q);
dff = ff;
dffclock = port(ff, \CLK);
dffD = argQ;
argD = port(ff, \D);
SigSpec D = port(ff, \D);
argQ = Q;
dffD.replace(argQ, argD);
// Only search for ffrstmux if dffD only
// has two (ff, ffrstmux) users
if (nusers(dffD) > 2)
argD = SigSpec();
endcode
// (2) Match for a $mux cell implementing synchronous reset semantics ---
// exclusively drives the 'D' input of the $dff, with one of the $mux
// inputs being fully zero
match ffrstmux
if !argD.empty()
select ffrstmux->type.in($mux)
index <SigSpec> port(ffrstmux, \Y) === argD
choice <IdString> BA {\B, \A}
// DSP48E1 only supports reset to zero
select port(ffrstmux, BA).is_fully_zero()
define <bool> pol (BA == \B)
set ffrstpol pol
semioptional
endmatch
code argD
if (ffrstmux) {
dffrstmux = ffrstmux;
dffrstpol = ffrstpol;
argD = port(ffrstmux, ffrstpol ? \A : \B);
dffD.replace(port(ffrstmux, \Y), argD);
// Only search for ffcemux if argQ has at
// least 3 users (ff, <upstream>, ffrstmux) and
// dffD only has two (ff, ffrstmux)
if (!(nusers(argQ) >= 3 && nusers(dffD) == 2))
argD = SigSpec();
}
else
dffrstmux = nullptr;
endcode
// (3) Match for a $mux cell implement clock enable semantics --- one that
// exclusively drives the 'D' input of the $dff (or the other input of
// the reset $mux) and where one of this $mux's inputs is connected to
// the 'Q' output of the $dff
match ffcemux
if !argD.empty()
select ffcemux->type.in($mux)
index <SigSpec> port(ffcemux, \Y) === argD
choice <IdString> AB {\A, \B}
index <SigSpec> port(ffcemux, AB) === argQ
define <bool> pol (AB == \A)
set ffcepol pol
semioptional
endmatch
code argD
if (ffcemux) {
dffcemux = ffcemux;
dffcepol = ffcepol;
argD = port(ffcemux, ffcepol ? \B : \A);
dffD.replace(port(ffcemux, \Y), argD);
}
else
dffcemux = nullptr;
dffD.replace(argQ, D);
endcode
// #######################
@ -543,119 +392,26 @@ code
reject;
endcode
// (1) Starting from an optional $mux cell that implements clock enable
// semantics --- one where the given 'D' argument (partially or fully)
// drives one of its two inputs
match ffcemux
select ffcemux->type.in($mux)
// ffcemux output must have two users: ffcemux and ff.D
select nusers(port(ffcemux, \Y)) == 2
choice <IdString> AB {\A, \B}
// keep-last-value net must have at least three users: ffcemux, ff, downstream sink(s)
select nusers(port(ffcemux, AB)) >= 3
slice offset GetSize(port(ffcemux, \Y))
define <IdString> BA (AB == \A ? \B : \A)
index <SigBit> port(ffcemux, BA)[offset] === argD[0]
// Check that the rest of argD is present
filter GetSize(port(ffcemux, BA)) >= offset + GetSize(argD)
filter port(ffcemux, BA).extract(offset, GetSize(argD)) == argD
set ffoffset offset
define <bool> pol (AB == \A)
set ffcepol pol
semioptional
endmatch
code argD argQ
dffcemux = ffcemux;
if (ffcemux) {
SigSpec BA = port(ffcemux, ffcepol ? \B : \A);
SigSpec Y = port(ffcemux, \Y);
argQ = argD;
argD.replace(BA, Y);
argQ.replace(BA, port(ffcemux, ffcepol ? \A : \B));
dffcemux = ffcemux;
dffcepol = ffcepol;
}
endcode
// (2) Starting from, or continuing onto, another optional $mux cell that
// implements synchronous reset semantics --- one where the given 'D'
// argument (or the clock enable $mux output) drives one of its two inputs
// and where the other input is fully zero
match ffrstmux
select ffrstmux->type.in($mux)
// ffrstmux output must have two users: ffrstmux and ff.D
select nusers(port(ffrstmux, \Y)) == 2
choice <IdString> BA {\B, \A}
// DSP48E1 only supports reset to zero
select port(ffrstmux, BA).is_fully_zero()
slice offset GetSize(port(ffrstmux, \Y))
define <IdString> AB (BA == \B ? \A : \B)
index <SigBit> port(ffrstmux, AB)[offset] === argD[0]
// Check that offset is consistent
filter !ffcemux || ffoffset == offset
// Check that the rest of argD is present
filter GetSize(port(ffrstmux, AB)) >= offset + GetSize(argD)
filter port(ffrstmux, AB).extract(offset, GetSize(argD)) == argD
set ffoffset offset
define <bool> pol (AB == \A)
set ffrstpol pol
semioptional
endmatch
code argD argQ
dffrstmux = ffrstmux;
if (ffrstmux) {
SigSpec AB = port(ffrstmux, ffrstpol ? \A : \B);
SigSpec Y = port(ffrstmux, \Y);
argD.replace(AB, Y);
dffrstmux = ffrstmux;
dffrstpol = ffrstpol;
}
endcode
// (3) Match for a $dff cell (whose 'D' input is the 'D' argument, or the
// output of the previous clock enable or reset $mux cells)
match ff
select ff->type.in($dff)
select ff->type.in($dff, $dffe, $sdff, $sdffe)
// DSP48E1 does not support clock inversion
select param(ff, \CLK_POLARITY).as_bool()
slice offset GetSize(port(ff, \D))
index <SigBit> port(ff, \D)[offset] === argD[0]
// Check that offset is consistent
filter (!ffcemux && !ffrstmux) || ffoffset == offset
// Check that the rest of argD is present
filter GetSize(port(ff, \D)) >= offset + GetSize(argD)
filter port(ff, \D).extract(offset, GetSize(argD)) == argD
// Check that FF.Q is connected to CE-mux
filter !ffcemux || port(ff, \Q).extract(offset, GetSize(argQ)) == argQ
filter clock == SigBit() || port(ff, \CLK) == clock
set ffoffset offset
endmatch
code argQ
SigSpec D = port(ff, \D);
SigSpec Q = port(ff, \Q);
if (!ffcemux) {
argQ = argD;
argQ.replace(D, Q);
}
argQ = argD;
argQ.replace(D, Q);
// Abandon matches when 'Q' has a non-zero init attribute set
// (not supported by DSP48E1)