extra_args(args, argidx, design);
for (auto module : design->selected_modules()) {
+ // Experimental feature: pack $add/$sub cells with
+ // (* use_dsp48="simd" *) into DSP48E1's using its
+ // SIMD feature
xilinx_simd_pack(module, module->selected_cells());
+ // Match for all features ([ABDMP][12]?REG, pre-adder,
+ // (post-adder, pattern detector, etc.) except for CREG
{
xilinx_dsp_pm pm(module, module->selected_cells());
pm.run_xilinx_dsp_pack(xilinx_dsp_pack);
// is no guarantee that the cell ordering corresponds
// to the "expected" case (i.e. the order in which
// they appear in the source) thus the possiblity
- // existed that a register got packed as CREG into a
+ // existed that a register got packed as a CREG into a
// downstream DSP that should have otherwise been a
- // PREG of an upstream DSP that had not been pattern
- // matched yet
+ // PREG of an upstream DSP that had not been visited
+ // yet
{
xilinx_dsp_CREG_pm pm(module, module->selected_cells());
pm.run_xilinx_dsp_packC(xilinx_dsp_packC);
}
+ // Lastly, identify and utilise PCOUT -> PCIN,
+ // ACOUT -> ACIN, and BCOUT-> BCIN dedicated cascade
+ // chains
{
xilinx_dsp_cascade_pm pm(module, module->selected_cells());
pm.run_xilinx_dsp_cascade();
+// This file describes the main pattern matcher setup (of three total) that
+// forms the `xilinx_dsp` pass described in xilinx_dsp.cc
+// At a high level, it works as follows:
+// ( 1) Starting from a DSP48E1 cell
+// ( 2) Match the driver of the 'A' input to a possible $dff cell (ADREG)
+// (attached to at most two $mux cells that implement clock-enable or
+// reset functionality, using a subpattern discussed below)
+// If ADREG matched, treat 'A' input as input of ADREG
+// ( 3) Match the driver of the 'A' and 'D' inputs for a possible $add cell
+// (pre-adder)
+// ( 4) If pre-adder was present, find match 'A' input for A2REG
+// If pre-adder was not present, move ADREG to A2REG
+// If A2REG, then match 'A' input for A1REG
+// ( 5) Match 'B' input for B2REG
+// If B2REG, then match 'B' input for B1REG
+// ( 6) Match 'D' input for DREG
+// ( 7) Match 'P' output that exclusively drives an MREG
+// ( 8) Match 'P' output that exclusively drives one of two inputs to an $add
+// cell (post-adder).
+// The other input to the adder is assumed to come in from the 'C' input
+// (note: 'P' -> 'C' connections that exist for accumulators are
+// recognised in xilinx_dsp.cc).
+// ( 9) Match 'P' output that exclusively drives a PREG
+// (10) If post-adder and PREG both present, match for a $mux cell driving
+// the 'C' input, where one of the $mux's inputs is the PREG output.
+// This indicates an accumulator situation, and one where a $mux exists
+// to override the accumulated value:
+// +--------------------------------+
+// | ____ |
+// +--| \ |
+// |$mux|-+ |
+// 'C' ---|____/ | |
+// | /-------\ +----+ |
+// +----+ +-| post- |___|PREG|---+ 'P'
+// |MREG|------ | adder | +----+
+// +----+ \-------/
+// (11) If PREG present, match for a greater-than-or-equal $ge cell attached
+// to the 'P' output where it is compared to a constant that is a
+// power-of-2: e.g. `assign overflow = (PREG >= 2**40);`
+// In this scenario, the pattern detector functionality of a DSP48E1 can
+// to implement this function
+// Notes:
+// - The intention of this pattern matcher is for it to be compatible with
+// DSP48E1 cells inferred from multiply operations by Yosys, as well as for
+// user instantiations that may already contain the cells being packed...
+// (though the latter is currently untested)
+// - Since the $dff-with-clock-enable-or-reset-mux pattern is used for each
+// *REG match, it has been factored out into two subpatterns: in_dffe
+// out_dffe located at the bottom of this file
+
pattern xilinx_dsp_pack
state <SigBit> clock
state <IdString> postAddAB postAddMuxAB
state <bool> ffA1cepol ffA2cepol ffADcepol ffB1cepol ffB2cepol ffDcepol ffMcepol ffPcepol
state <bool> ffArstpol ffADrstpol ffBrstpol ffDrstpol ffMrstpol ffPrstpol
-
state <Cell*> ffAD ffADcemux ffADrstmux ffA1 ffA1cemux ffA1rstmux ffA2 ffA2cemux ffA2rstmux
state <Cell*> ffB1 ffB1cemux ffB1rstmux ffB2 ffB2cemux ffB2rstmux
state <Cell*> ffD ffDcemux ffDrstmux ffM ffMcemux ffMrstmux ffP ffPcemux ffPrstmux
-// subpattern
+// Variables used for subpatterns
state <SigSpec> argQ argD
state <bool> ffcepol ffrstpol
state <int> ffoffset
udata <Cell*> dff dffcemux dffrstmux
udata <bool> dffcepol dffrstpol
+// (1) Starting from a DSP48E1 cell
match dsp
select dsp->type.in(\DSP48E1)
endmatch
}
else
sigM = P;
+ // TODO: Check if necessary
// This sigM could have no users if downstream $add
// is narrower than $mul result, for example
if (sigM.empty())
clock = port(dsp, \CLK, SigBit());
endcode
+// (2) Match the driver of the 'A' input to a possible $dff cell (ADREG)
+// (attached to at most two $mux cells that implement clock-enable or
+// reset functionality, using a subpattern discussed above)
+// If matched, treat 'A' input as input of ADREG
code argQ ffAD ffADcemux ffADrstmux ffADcepol ffADrstpol sigA clock
if (param(dsp, \ADREG).as_int() == 0) {
argQ = sigA;
}
endcode
+// (3) Match the driver of the 'A' and 'D' inputs for a possible $add cell
+// (pre-adder)
match preAdd
if sigD.empty() || sigD.is_fully_zero()
// Ensure that preAdder not already used
endmatch
code sigA sigD
+ // TODO: Check if this is necessary?
if (preAdd) {
sigA = port(preAdd, \A);
sigD = port(preAdd, \B);
}
endcode
+// (4) If pre-adder was present, find match 'A' input for A2REG
+// If pre-adder was not present, move ADREG to A2REG
+// Then match 'A' input for A1REG
code argQ ffAD ffADcemux ffADrstmux ffADcepol ffADrstpol sigA clock ffA2 ffA2cemux ffA2rstmux ffA2cepol ffArstpol ffA1 ffA1cemux ffA1rstmux ffA1cepol
// Only search for ffA2 if there was a pre-adder
// (otherwise ffA2 would have been matched as ffAD)
}
endcode
+// (5) Match 'B' input for B2REG
+// If B2REG, then match 'B' input for B1REG
code argQ ffB2 ffB2cemux ffB2rstmux ffB2cepol ffBrstpol sigB clock ffB1 ffB1cemux ffB1rstmux ffB1cepol
if (param(dsp, \BREG).as_int() == 0) {
argQ = sigB;
}
endcode
+// (6) Match 'D' input for DREG
code argQ ffD ffDcemux ffDrstmux ffDcepol ffDrstpol sigD clock
if (param(dsp, \DREG).as_int() == 0) {
argQ = sigD;
}
endcode
+// (7) Match 'P' output that exclusively drives an MREG
code argD ffM ffMcemux ffMrstmux ffMcepol ffMrstpol sigM sigP clock
if (param(dsp, \MREG).as_int() == 0 && nusers(sigM) == 2) {
argD = sigM;
sigP = sigM;
endcode
+// (8) Match 'P' output that exclusively drives one of two inputs to an $add
+// cell (post-adder).
+// The other input to the adder is assumed to come in from the 'C' input
+// (note: 'P' -> 'C' connections that exist for accumulators are
+// recognised in xilinx_dsp.cc).
match postAdd
// Ensure that Z mux is not already used
if port(dsp, \OPMODE, SigSpec()).extract(4,3).is_fully_zero()
}
endcode
+// (9) Match 'P' output that exclusively drives a PREG
code argD ffP ffPcemux ffPrstmux ffPcepol ffPrstpol sigP clock
if (param(dsp, \PREG).as_int() == 0) {
int users = 2;
}
endcode
+// (10) If post-adder and PREG both present, match for a $mux cell driving
+// the 'C' input, where one of the $mux's inputs is the PREG output.
+// This indicates an accumulator situation, and one where a $mux exists
+// to override the accumulated value:
+// +--------------------------------+
+// | ____ |
+// +--| \ |
+// |$mux|-+ |
+// 'C' ---|____/ | |
+// | /-------\ +----+ |
+// +----+ +-| post- |___|PREG|---+ 'P'
+// |MREG|------ | adder | +----+
+// +----+ \-------/
match postAddMux
if postAdd
if ffP
sigC = port(postAddMux, postAddMuxAB == \A ? \B : \A);
endcode
+// (11) If PREG present, match for a greater-than-or-equal $ge cell attached to
+// the 'P' output where it is compared to a constant that is a power-of-2:
+// e.g. `assign overflow = (PREG >= 2**40);`
+// In this scenario, the pattern detector functionality of a DSP48E1 can
+// to implement this function
match overflow
if ffP
if param(dsp, \USE_PATTERN_DETECT, Const("NO_PATDET")).decode_string() == "NO_PATDET"
+// This file describes the second of three pattern matcher setups that
+// forms the `xilinx_dsp` pass described in xilinx_dsp.cc
+// At a high level, it works as follows:
+// (1) Starting from a DSP48E1 cell that (a) doesn't have a CREG already,
+// and (b) uses the 'C' port
+// (2) Match the driver of the 'C' input to a possible $dff cell (CREG)
+// (attached to at most two $mux cells that implement clock-enable or
+// reset functionality, using a subpattern discussed below)
+// Notes:
+// - Separating out CREG packing is necessary since there is no guarantee
+// that the cell ordering corresponds to the "expected" case (i.e. the order
+// in which they appear in the source) thus the possiblity existed that a
+// register got packed as a CREG into a downstream DSP that should have
+// otherwise been a PREG of an upstream DSP that had not been visited yet
+// - The reason this is separated out from the xilinx_dsp.pmg file is
+// for efficiency --- each *.pmg file creates a class of the same basename,
+// which when constructed, creates a custom database tailored to the
+// pattern(s) contained within. Since the pattern in this file must be
+// executed after the pattern contained in xilinx_dsp.pmg, it is necessary
+// to reconstruct this database. Separating the two patterns into
+// independent files causes two smaller, more specific, databases.
+
pattern xilinx_dsp_packC
udata <std::function<SigSpec(const SigSpec&)>> unextend
udata <Cell*> dff dffcemux dffrstmux
udata <bool> dffcepol dffrstpol
+// (1) Starting from a DSP48E1 cell that (a) doesn't have a CREG already,
+// and (b) uses the 'C' port
match dsp
select dsp->type.in(\DSP48E1)
select param(dsp, \CREG, 1).as_int() == 0
select nusers(port(dsp, \C, SigSpec())) > 1
endmatch
-code argQ ffC ffCcemux ffCrstmux ffCcepol ffCrstpol sigC sigP clock
+code sigC sigP
unextend = [](const SigSpec &sig) {
int i;
for (i = GetSize(sig)-1; i > 0; i--)
}
else
sigP = P;
+endcode
+// (2) Match the driver of the 'C' input to a possible $dff cell (CREG)
+// (attached to at most two $mux cells that implement clock-enable or
+// reset functionality, using a subpattern discussed below)
+code argQ ffC ffCcemux ffCrstmux ffCcepol ffCrstpol sigC clock
+ // TODO: Any downside to allowing this?
+ // If this DSP implements an accumulator, do not attempt to match
if (sigC == sigP)
reject;
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