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Diffstat (limited to 'passes/pmgen/xilinx_dsp48a.pmg')
| -rw-r--r-- | passes/pmgen/xilinx_dsp48a.pmg | 673 |
1 files changed, 673 insertions, 0 deletions
diff --git a/passes/pmgen/xilinx_dsp48a.pmg b/passes/pmgen/xilinx_dsp48a.pmg new file mode 100644 index 000000000..16f5e598d --- /dev/null +++ b/passes/pmgen/xilinx_dsp48a.pmg @@ -0,0 +1,673 @@ +// This file describes the main pattern matcher setup (of three total) that +// forms the `xilinx_dsp` pass described in xilinx_dsp.cc - version for +// DSP48A/DSP48A1 (Spartan 3A DSP, Spartan 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) +// ( 4) Match 'B' input for B0REG +// ( 5) Match 'A' input for A1REG +// If A1REG, then match 'A' input for A0REG +// ( 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 | +----+ +// +----+ \-------/ +// Notes: see the notes in xilinx_dsp.pmg + +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 + +// 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 + +// (1) Starting from a DSP48A/DSP48A1 cell +match dsp + select dsp->type.in(\DSP48A, \DSP48A1) +endmatch + +code sigA sigB sigC sigD sigM clock + auto unextend = [](const SigSpec &sig) { + int i; + for (i = GetSize(sig)-1; i > 0; i--) + if (sig[i] != sig[i-1]) + break; + // Do not remove non-const sign bit + if (sig[i].wire) + ++i; + return sig.extract(0, i); + }; + sigA = unextend(port(dsp, \A)); + sigB = unextend(port(dsp, \B)); + + sigC = port(dsp, \C, SigSpec()); + sigD = port(dsp, \D, SigSpec()); + + SigSpec P = port(dsp, \P); + // Only care about those bits that are used + int i; + for (i = GetSize(P)-1; i >= 0; i--) + if (nusers(P[i]) > 1) + break; + i++; + log_assert(nusers(P.extract_end(i)) <= 1); + // This sigM could have no users if downstream sinks (e.g. $add) is + // narrower than $mul result, for example + if (i == 0) + reject; + sigM = P.extract(0, i); + + clock = port(dsp, \CLK, SigBit()); +endcode + +// (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 above) +// If matched, treat 'B' input as input of B1REG +code argQ ffB1 ffB1cemux ffB1rstmux ffBcepol ffBrstpol 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; + } + } +endcode + +// (3) Match the driver of the 'B' and 'D' inputs for a possible $add cell +// (pre-adder) +match preAdd + if sigD.empty() || sigD.is_fully_zero() + if param(dsp, \B0REG).as_int() == 0 + // Ensure that preAdder not already used + if port(dsp, \OPMODE, SigSpec()).extract(4, 1).is_fully_zero() + + select preAdd->type.in($add, $sub) + // Output has to be 18 bits or less + select GetSize(port(preAdd, \Y)) <= 18 + select nusers(port(preAdd, \Y)) == 2 + // D port has to be 18 bits or less + select GetSize(port(preAdd, \A)) <= 18 + // B port has to be 18 bits or less + select GetSize(port(preAdd, \B)) <= 18 + index <SigSpec> port(preAdd, \Y) === sigB + + optional +endmatch + +code sigB sigD + if (preAdd) { + sigD = port(preAdd, \A); + sigB = port(preAdd, \B); + } +endcode + +// (4) Match 'B' input for B0REG +code argQ ffB0 ffB0cemux ffB0rstmux ffBcepol ffBrstpol sigB clock + if (param(dsp, \B0REG).as_int() == 0) { + argQ = sigB; + subpattern(in_dffe); + if (dff) { + if (ffB1) { + if ((ffB1rstmux != nullptr) ^ (dffrstmux != nullptr)) + goto ffB0_end; + if ((ffB1cemux != nullptr) ^ (dffcemux != nullptr)) + goto ffB0_end; + if (dffrstmux) { + if (ffBrstpol != dffrstpol) + goto ffB0_end; + if (port(ffB1rstmux, \S) != port(dffrstmux, \S)) + goto ffB0_end; + ffB0rstmux = dffrstmux; + } + if (dffcemux) { + if (ffBcepol != dffcepol) + goto ffB0_end; + if (port(ffB1cemux, \S) != port(dffcemux, \S)) + goto ffB0_end; + ffB0cemux = dffcemux; + } + } + ffB0 = dff; + clock = dffclock; + if (dffrstmux) { + ffB0rstmux = dffrstmux; + ffBrstpol = dffrstpol; + } + if (dffcemux) { + ffB0cemux = dffcemux; + ffBcepol = dffcepol; + } + sigB = dffD; + } + } +ffB0_end: +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 + 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 + if (ffA1) { + argQ = sigA; + subpattern(in_dffe); + if (dff) { + if ((ffA1rstmux != nullptr) ^ (dffrstmux != nullptr)) + goto ffA0_end; + if ((ffA1cemux != nullptr) ^ (dffcemux != nullptr)) + goto ffA0_end; + if (dffrstmux) { + if (ffArstpol != dffrstpol) + goto ffA0_end; + if (port(ffA1rstmux, \S) != port(dffrstmux, \S)) + goto ffA0_end; + ffA0rstmux = dffrstmux; + } + if (dffcemux) { + if (ffAcepol != dffcepol) + goto ffA0_end; + if (port(ffA1cemux, \S) != port(dffcemux, \S)) + goto ffA0_end; + ffA0cemux = dffcemux; + } + + ffA0 = dff; + clock = dffclock; + + if (dffcemux) { + ffA0cemux = dffcemux; + ffAcepol = dffcepol; + } + sigA = dffD; + +ffA0_end: ; + } + } + + } + } +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; + 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 + 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; + } + } + sigP = sigM; +endcode + +// (8) Match 'P' output that exclusively drives one of two inputs to an $add +// cell (post-adder). +// The other input to the adder is assumed to come in from the 'C' input +// (note: 'P' -> 'C' connections that exist for accumulators are +// recognised in xilinx_dsp.cc). +match postAdd + // Ensure that Z mux is not already used + if port(dsp, \OPMODE, SigSpec()).extract(2,2).is_fully_zero() + + select postAdd->type.in($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 + + index <SigBit> port(postAdd, AB)[0] === sigP[0] + filter GetSize(port(postAdd, AB)) >= GetSize(sigP) + filter port(postAdd, AB).extract(0, GetSize(sigP)) == sigP + // Check that remainder of AB is a sign- or zero-extension + filter port(postAdd, AB).extract_end(GetSize(sigP)) == SigSpec(sigP[GetSize(sigP)-1], GetSize(port(postAdd, AB))-GetSize(sigP)) || port(postAdd, AB).extract_end(GetSize(sigP)) == SigSpec(State::S0, GetSize(port(postAdd, AB))-GetSize(sigP)) + + set postAddAB AB + optional +endmatch + +code sigC sigP + if (postAdd) { + sigC = port(postAdd, postAddAB == \A ? \B : \A); + sigP = port(postAdd, \Y); + } +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; + // If ffMcemux and no postAdd new-value net must have three users: ffMcemux, ffM and ffPcemux + if (ffMcemux && !postAdd) users++; + if (nusers(sigP) == users) { + 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; + } + } + } +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 + select postAddMux->type.in($mux) + select nusers(port(postAddMux, \Y)) == 2 + choice <IdString> AB {\A, \B} + index <SigSpec> port(postAddMux, AB) === sigP + index <SigSpec> port(postAddMux, \Y) === sigC + set postAddMuxAB AB + optional +endmatch + +code sigC + if (postAddMux) + sigC = port(postAddMux, postAddMuxAB == \A ? \B : \A); +endcode + +code + accept; +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 +subpattern in_dffe +arg argD argQ clock + +code + dff = nullptr; + if (GetSize(argQ) == 0) + reject; + for (const auto &c : argQ.chunks()) { + // Abandon matches when 'Q' is a constant + if (!c.wire) + reject; + // Abandon matches when 'Q' has the keep attribute set + if (c.wire->get_bool_attribute(\keep)) + reject; + // Abandon matches when 'Q' has a non-zero init attribute set + // (not supported by DSP48E1) + Const init = c.wire->attributes.at(\init, Const()); + if (!init.empty()) + for (auto b : init.extract(c.offset, c.width)) + if (b != State::Sx && b != State::S0) + reject; + } +endcode + +// (1) Starting from a $dff cell that (partially or fully) drives the given +// 'Q' argument +match ff + select ff->type.in($dff) + // DSP48E1 does not support clock inversion + select param(ff, \CLK_POLARITY).as_bool() + + slice offset GetSize(port(ff, \D)) + index <SigBit> port(ff, \Q)[offset] === argQ[0] + + // Check that the rest of argQ is present + filter GetSize(port(ff, \Q)) >= offset + GetSize(argQ) + filter port(ff, \Q).extract(offset, GetSize(argQ)) == argQ + + filter clock == SigBit() || port(ff, \CLK) == clock + + set ffoffset offset +endmatch + +code argQ argD + SigSpec Q = port(ff, \Q); + dff = ff; + dffclock = port(ff, \CLK); + dffD = argQ; + argD = 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; +endcode + +// ####################### + +// Subpattern for matching against output registers, based on knowledge of the +// 'D' input. +// At a high level: +// (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 +// (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 +// (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) +subpattern out_dffe +arg argD argQ clock + +code + dff = nullptr; + for (auto c : argD.chunks()) + // Abandon matches when 'D' has the keep attribute set + if (c.wire->get_bool_attribute(\keep)) + 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) + // 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); + } + + // Abandon matches when 'Q' has a non-zero init attribute set + // (not supported by DSP48E1) + for (auto c : argQ.chunks()) { + Const init = c.wire->attributes.at(\init, Const()); + if (!init.empty()) + for (auto b : init.extract(c.offset, c.width)) + if (b != State::Sx && b != State::S0) + reject; + } + + dff = ff; + dffQ = argQ; + dffclock = port(ff, \CLK); +endcode |