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DFG: Partial support for unpacked arrays

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Representation and Ast / Dfg conversions available, for element-wise
access only. Not much optimization yet (only CSE).
This commit is contained in:
Geza Lore
2022-09-29 19:00:45 +01:00
parent 4a1a2def95
commit acebafcbc2
6 changed files with 400 additions and 196 deletions
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src/V3DfgAstToDfg.cpp
+114 -81
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@@ -35,8 +35,6 @@
#include "V3Error.h"
#include "V3Global.h"
#include <tuple>
VL_DEFINE_DEBUG_FUNCTIONS;
namespace {
@@ -88,7 +86,8 @@ class AstToDfgVisitor final : public VNVisitor {
bool m_foundUnhandled = false; // Found node not implemented as DFG or not implemented 'visit'
std::vector<DfgVertex*> m_uncommittedVertices; // Vertices that we might decide to revert
bool m_converting = false; // We are trying to convert some logic at the moment
std::vector<DfgVar*> m_varps; // All the DfgVar vertices we created.
std::vector<DfgVarPacked*> m_varPackedps; // All the DfgVarPacked vertices we created.
std::vector<DfgVarArray*> m_varArrayps; // All the DfgVarArray vertices we created.
// METHODS
void markReferenced(AstNode* nodep) {
@@ -106,18 +105,25 @@ class AstToDfgVisitor final : public VNVisitor {
m_uncommittedVertices.clear();
}
DfgVar* getNet(AstVar* varp) {
DfgVertexLValue* getNet(AstVar* varp) {
if (!varp->user1p()) {
// Note DfgVar vertices are not added to m_uncommittedVertices, because we want to
// hold onto them via AstVar::user1p, and the AstVar which might be referenced via
// multiple AstVarRef instances, so we will never revert a DfgVar once created. This
// means we can end up with DfgVar vertices in the graph which have no connections at
// all (which is fine for later processing).
DfgVar* const vtxp = new DfgVar{*m_dfgp, varp};
m_varps.push_back(vtxp);
varp->user1p(vtxp);
// Note DfgVertexLValue vertices are not added to m_uncommittedVertices, because we
// want to hold onto them via AstVar::user1p, and the AstVar might be referenced via
// multiple AstVarRef instances, so we will never revert a DfgVertexLValue once
// created. This means we can end up with DfgVertexLValue vertices in the graph which
// have no connections at all (which is fine for later processing).
if (VN_IS(varp->dtypep()->skipRefp(), UnpackArrayDType)) {
DfgVarArray* const vtxp = new DfgVarArray{*m_dfgp, varp};
varp->user1p();
m_varArrayps.push_back(vtxp);
varp->user1p(vtxp);
} else {
DfgVarPacked* const vtxp = new DfgVarPacked{*m_dfgp, varp};
m_varPackedps.push_back(vtxp);
varp->user1p(vtxp);
}
}
return varp->user1u().to<DfgVar*>();
return varp->user1u().to<DfgVertexLValue*>();
}
DfgVertex* getVertex(AstNode* nodep) {
@@ -150,12 +156,12 @@ class AstToDfgVisitor final : public VNVisitor {
m_foundUnhandled = false;
visit(vrefp);
if (m_foundUnhandled) return false;
getVertex(vrefp)->as<DfgVar>()->addDriver(flp, 0, vtxp);
getVertex(vrefp)->as<DfgVarPacked>()->addDriver(flp, 0, vtxp);
return true;
}
if (AstSel* const selp = VN_CAST(nodep, Sel)) {
AstVarRef* const vrefp = VN_CAST(selp->fromp(), VarRef);
AstConst* const lsbp = VN_CAST(selp->lsbp(), Const);
const AstConst* const lsbp = VN_CAST(selp->lsbp(), Const);
if (!vrefp || !lsbp || !VN_IS(selp->widthp(), Const)) {
++m_ctx.m_nonRepLhs;
return false;
@@ -163,7 +169,20 @@ class AstToDfgVisitor final : public VNVisitor {
m_foundUnhandled = false;
visit(vrefp);
if (m_foundUnhandled) return false;
getVertex(vrefp)->as<DfgVar>()->addDriver(flp, lsbp->toUInt(), vtxp);
getVertex(vrefp)->as<DfgVarPacked>()->addDriver(flp, lsbp->toUInt(), vtxp);
return true;
}
if (AstArraySel* const selp = VN_CAST(nodep, ArraySel)) {
AstVarRef* const vrefp = VN_CAST(selp->fromp(), VarRef);
const AstConst* const idxp = VN_CAST(selp->bitp(), Const);
if (!vrefp || !idxp) {
++m_ctx.m_nonRepLhs;
return false;
}
m_foundUnhandled = false;
visit(vrefp);
if (m_foundUnhandled) return false;
getVertex(vrefp)->as<DfgVarArray>()->addDriver(flp, idxp->toUInt(), vtxp);
return true;
}
if (AstConcat* const concatp = VN_CAST(nodep, Concat)) {
@@ -197,6 +216,15 @@ class AstToDfgVisitor final : public VNVisitor {
bool convertEquation(AstNode* nodep, AstNode* lhsp, AstNode* rhsp) {
UASSERT_OBJ(m_uncommittedVertices.empty(), nodep, "Should not nest");
// Currently cannot handle direct assignments between unpacked types. These arise e.g.
// when passing an unpacked array through a module port.
if (!DfgVertex::isSupportedPackedDType(lhsp->dtypep())
|| !DfgVertex::isSupportedPackedDType(rhsp->dtypep())) {
markReferenced(nodep);
++m_ctx.m_nonRepDType;
return false;
}
// Cannot handle mismatched widths. Mismatched assignments should have been fixed up in
// earlier passes anyway, so this should never be hit, but being paranoid just in case.
if (lhsp->width() != rhsp->width()) { // LCOV_EXCL_START
@@ -233,6 +261,73 @@ class AstToDfgVisitor final : public VNVisitor {
return true;
}
// Canonicalize packed variables
void canonicalizePacked() {
for (DfgVarPacked* const varp : m_varPackedps) {
// Gather (and unlink) all drivers
struct Driver {
FileLine* flp;
uint32_t lsb;
DfgVertex* vtxp;
Driver(FileLine* flp, uint32_t lsb, DfgVertex* vtxp)
: flp{flp}
, lsb{lsb}
, vtxp{vtxp} {}
};
std::vector<Driver> drivers;
drivers.reserve(varp->arity());
varp->forEachSourceEdge([varp, &drivers](DfgEdge& edge, size_t idx) {
UASSERT(edge.sourcep(), "Should not have created undriven sources");
drivers.emplace_back(varp->driverFileLine(idx), varp->driverLsb(idx),
edge.sourcep());
edge.unlinkSource();
});
// Sort drivers by LSB
std::stable_sort(drivers.begin(), drivers.end(),
[](const Driver& a, const Driver& b) { return a.lsb < b.lsb; });
// TODO: bail on multidriver
// Coalesce adjacent ranges
for (size_t i = 0, j = 1; j < drivers.size(); ++j) {
Driver& a = drivers[i];
Driver& b = drivers[j];
// Coalesce adjacent range
const uint32_t aWidth = a.vtxp->width();
const uint32_t bWidth = b.vtxp->width();
if (a.lsb + aWidth == b.lsb) {
const auto dtypep = DfgVertex::dtypeForWidth(aWidth + bWidth);
DfgConcat* const concatp = new DfgConcat{*m_dfgp, a.flp, dtypep};
concatp->rhsp(a.vtxp);
concatp->lhsp(b.vtxp);
a.vtxp = concatp;
b.vtxp = nullptr; // Mark as moved
++m_ctx.m_coalescedAssignments;
continue;
}
++i;
// Compact non-adjacent ranges within the vector
if (j != i) {
Driver& c = drivers[i];
UASSERT_OBJ(!c.vtxp, c.flp, "Should have been marked moved");
c = b;
b.vtxp = nullptr; // Mark as moved
}
}
// Reinsert sources in order
varp->resetSources();
for (const Driver& driver : drivers) {
if (!driver.vtxp) break; // Stop at end of cmpacted list
varp->addDriver(driver.flp, driver.lsb, driver.vtxp);
}
}
}
// VISITORS
void visit(AstNode* nodep) override {
// Conservatively treat this node as unhandled
@@ -298,7 +393,7 @@ class AstToDfgVisitor final : public VNVisitor {
nodep->user1p(vtxp);
}
// The rest of the 'visit' methods are generated by 'astgen'
// The rest of the 'visit' methods are generated by 'astgen'
#include "V3Dfg__gen_ast_to_dfg.h"
// CONSTRUCTOR
@@ -309,70 +404,8 @@ class AstToDfgVisitor final : public VNVisitor {
iterateChildren(&module);
UASSERT_OBJ(m_uncommittedVertices.empty(), &module, "Uncommitted vertices remain");
// Canonicalize variable assignments
for (DfgVar* const varp : m_varps) {
// Gather (and unlink) all drivers
struct Driver {
FileLine* flp;
uint32_t lsb;
DfgVertex* vtxp;
Driver(FileLine* flp, uint32_t lsb, DfgVertex* vtxp)
: flp{flp}
, lsb{lsb}
, vtxp{vtxp} {}
};
std::vector<Driver> drivers;
drivers.reserve(varp->arity());
varp->forEachSourceEdge([varp, &drivers](DfgEdge& edge, size_t idx) {
UASSERT(edge.sourcep(), "Should not have created undriven sources");
drivers.emplace_back(varp->driverFileLine(idx), varp->driverLsb(idx),
edge.sourcep());
edge.unlinkSource();
});
// Sort drivers by LSB
std::stable_sort(drivers.begin(), drivers.end(),
[](const Driver& a, const Driver& b) { return a.lsb < b.lsb; });
// TODO: bail on multidriver
// Coalesce adjacent ranges
for (size_t i = 0, j = 1; j < drivers.size(); ++j) {
Driver& a = drivers[i];
Driver& b = drivers[j];
// Coalesce adjacent range
const uint32_t aWidth = a.vtxp->width();
const uint32_t bWidth = b.vtxp->width();
if (a.lsb + aWidth == b.lsb) {
const auto dtypep = DfgVertex::dtypeForWidth(aWidth + bWidth);
DfgConcat* const concatp = new DfgConcat{*m_dfgp, a.flp, dtypep};
concatp->rhsp(a.vtxp);
concatp->lhsp(b.vtxp);
a.vtxp = concatp;
b.vtxp = nullptr; // Mark as moved
++m_ctx.m_coalescedAssignments;
continue;
}
++i;
// Compact non-adjacent ranges within the vector
if (j != i) {
Driver& c = drivers[i];
UASSERT_OBJ(!c.vtxp, c.flp, "Should have been marked moved");
c = b;
b.vtxp = nullptr; // Mark as moved
}
}
// Reinsert sources in order
varp->resetSources();
for (const Driver& driver : drivers) {
if (!driver.vtxp) break; // Stop at end of cmpacted list
varp->addDriver(driver.flp, driver.lsb, driver.vtxp);
}
}
// Canonicalize variables
canonicalizePacked();
}
public: