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Use AstNode::foreach in V3Gate

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This yields a little speedup.
This commit is contained in:
Geza Lore 2022-07-31 18:36:56 +01:00
parent 152a6cd886
commit 2ab6272cc7
2 changed files with 78 additions and 110 deletions
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7
src/V3Ast.h
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@ -2040,7 +2040,12 @@ template <> inline bool AstNode::mayBeUnder<AstNodeAssign>(const AstNode* nodep)
return !VN_IS(nodep, NodeMath);
}
template <> inline bool AstNode::mayBeUnder<AstVarScope>(const AstNode* nodep) {
return !VN_IS(nodep, NodeStmt) && !VN_IS(nodep, NodeMath);
if (VN_IS(nodep, VarScope)) return false; // Should not nest
if (VN_IS(nodep, Var)) return false;
if (VN_IS(nodep, Active)) return false;
if (VN_IS(nodep, NodeStmt)) return false;
if (VN_IS(nodep, NodeMath)) return false;
return true;
}
template <> inline bool AstNode::mayBeUnder<AstExecGraph>(const AstNode* nodep) {
if (VN_IS(nodep, ExecGraph)) return false; // Should not nest

181
src/V3Gate.cpp
View File

@ -34,9 +34,10 @@
#include <algorithm>
#include <list>
#include <map>
#include <unordered_set>
class GateDedupeVarVisitor;
using GateVarRefList = std::list<AstNodeVarRef*>;
constexpr int GATE_DEDUP_MAX_DEPTH = 20;
@ -297,6 +298,12 @@ public:
const GateVarRefList& rhsVarRefs() const { return m_rhsVarRefs; }
};
//######################################################################
// Replace refs to 'varscp' with 'substp' in 'consumerp'
static bool eliminate(AstNode* consumerp, AstVarScope* varscp, AstNode* substp,
GateDedupeVarVisitor* varVisp);
//######################################################################
// Gate class functions
@ -368,9 +375,23 @@ private:
return vertexp;
}
void optimizeElimVar(AstVarScope* varscp, AstNode* substp, AstNode* consumerp) {
if (debug() >= 5) consumerp->dumpTree(cout, " elimUsePre: ");
const bool replaced = eliminate(consumerp, varscp, substp, nullptr);
if (!replaced) return;
if (debug() >= 9) consumerp->dumpTree(cout, " elimUseCns: ");
// Caution: Can't let V3Const change our handle to consumerp, such as by
// optimizing away this assignment, etc.
consumerp = V3Const::constifyEdit(consumerp);
if (debug() >= 5) consumerp->dumpTree(cout, " elimUseDne: ");
// Some previous input edges may have disappeared, perhaps all of them.
// If we remove the edges we can further optimize
// See e.g t_var_overzero.v.
}
void optimizeSignals(bool allowMultiIn);
bool elimLogicOkOutputs(GateLogicVertex* consumeVertexp, const GateOkVisitor& okVisitor);
void optimizeElimVar(AstVarScope* varscp, AstNode* substp, AstNode* consumerp);
void warnSignals();
void consumedMark();
void consumedMarkRecurse(GateEitherVertex* vertexp);
@ -817,83 +838,6 @@ void GateVisitor::warnSignals() {
}
}
//######################################################################
// Push constant into expressions and reevaluate
class GateDedupeVarVisitor;
class GateElimVisitor final : public GateBaseVisitor {
private:
// NODE STATE
// STATE
const AstVarScope* const m_elimVarScp; // Variable being eliminated
AstNode* const m_replaceTreep; // What to replace the variable with
bool m_didReplace = false; // Did we do any replacements
GateDedupeVarVisitor* const m_varVisp; // Callback to keep hash up to date
// METHODS
void hashReplace(AstNode* oldp, AstNode* newp);
// VISITORS
virtual void visit(AstNodeVarRef* nodep) override {
if (nodep->varScopep() == m_elimVarScp) {
// Substitute in the new tree
// It's possible we substitute into something that will be reduced more later,
// however, as we never delete the top Always/initial statement, all should be well.
m_didReplace = true;
UASSERT_OBJ(nodep->access().isReadOnly(), nodep,
"Can't replace lvalue assignments with const var");
AstNode* const substp = m_replaceTreep->cloneTree(false);
UASSERT_OBJ(!(VN_IS(substp, NodeVarRef) && nodep->same(substp)),
// Prevent an infinite loop...
substp, "Replacing node with itself; perhaps circular logic?");
// Which fileline() to use?
// If replacing with logic, an error/warning is likely to want to point to the logic
// IE what we're replacing with.
// However a VARREF should point to the original as it's otherwise confusing
// to throw warnings that point to a PIN rather than where the pin us used.
if (VN_IS(substp, VarRef)) substp->fileline(nodep->fileline());
// Make the substp an rvalue like nodep. This facilitates the hashing in dedupe.
if (AstNodeVarRef* const varrefp = VN_CAST(substp, NodeVarRef))
varrefp->access(VAccess::READ);
hashReplace(nodep, substp);
nodep->replaceWith(substp);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
}
}
virtual void visit(AstNode* nodep) override { iterateChildren(nodep); }
public:
// CONSTRUCTORS
virtual ~GateElimVisitor() override = default;
GateElimVisitor(AstNode* nodep, AstVarScope* varscp, AstNode* replaceTreep,
GateDedupeVarVisitor* varVisp)
: m_elimVarScp{varscp}
, m_replaceTreep{replaceTreep}
, m_varVisp{varVisp} {
UINFO(9, " elimvisitor " << nodep << endl);
UINFO(9, " elim varscp " << varscp << endl);
UINFO(9, " elim repce " << replaceTreep << endl);
iterate(nodep);
}
bool didReplace() const { return m_didReplace; }
};
void GateVisitor::optimizeElimVar(AstVarScope* varscp, AstNode* substp, AstNode* consumerp) {
if (debug() >= 5) consumerp->dumpTree(cout, " elimUsePre: ");
const GateElimVisitor elimVisitor{consumerp, varscp, substp, nullptr};
if (elimVisitor.didReplace()) {
if (debug() >= 9) consumerp->dumpTree(cout, " elimUseCns: ");
// Caution: Can't let V3Const change our handle to consumerp, such as by
// optimizing away this assignment, etc.
consumerp = V3Const::constifyEdit(consumerp);
if (debug() >= 5) consumerp->dumpTree(cout, " elimUseDne: ");
// Some previous input edges may have disappeared, perhaps all of them.
// If we remove the edges we can further optimize
// See e.g t_var_overzero.v.
}
}
//######################################################################
// Auxiliary hash class for GateDedupeVarVisitor
@ -1113,9 +1057,47 @@ public:
//######################################################################
void GateElimVisitor::hashReplace(AstNode* oldp, AstNode* newp) {
UINFO(9, "hashReplace " << (void*)oldp << " -> " << (void*)newp << endl);
if (m_varVisp) m_varVisp->hashReplace(oldp, newp);
static bool eliminate(AstNode* consumerp, AstVarScope* varscp, AstNode* substp,
GateDedupeVarVisitor* varVisp) {
UINFO(9, " Eliminating inside: " << consumerp << endl);
UINFO(9, " Eliminating varscopep: " << varscp << endl);
UINFO(9, " Eliminating substitute: " << substp << endl);
bool didReplace = false; // Did we do any replacements
consumerp->foreach<AstNodeVarRef>([=, &didReplace](AstNodeVarRef* nodep) {
if (nodep->varScopep() != varscp) return;
// Substitute in the new tree
#ifdef VL_DEBUG // Can be hot code, so expensive
UASSERT_OBJ(nodep->access().isReadOnly(), nodep,
"Can't replace lvalue assignments with const var");
UASSERT_OBJ(!(VN_IS(substp, NodeVarRef) && nodep->same(substp)),
// Prevent an infinite loop...
substp, "Replacing node with itself; perhaps circular logic?");
#endif
// It's possible we substitute into something that will be reduced more later,
// however, as we never delete the top Always/initial statement, all should be well.
didReplace = true;
// The replacement
AstNode* const newp = substp->cloneTree(false);
// Which fileline() to use? If replacing with logic, an error/warning is likely to want
// to point to the logic IE what we're replacing with. However, a VARREF should point
// to the original as it's otherwise confusing to throw warnings that point to a PIN
// rather than where the pin us used.
if (VN_IS(newp, VarRef)) newp->fileline(nodep->fileline());
// Make the newp an rvalue like nodep. This facilitates the hashing in dedupe.
if (AstNodeVarRef* const varrefp = VN_CAST(newp, NodeVarRef)) {
varrefp->access(VAccess::READ);
}
// Update hash?
if (varVisp) varVisp->hashReplace(nodep, newp);
// Replace the node
nodep->replaceWith(newp);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
});
return didReplace;
}
//######################################################################
@ -1170,8 +1152,7 @@ private:
if (lvertexp == consumeVertexp) {
UINFO(9, "skipping as self-recirculates\n");
} else {
const GateElimVisitor elimVisitor(consumerp, vvertexp->varScp(),
dupVarRefp, &m_varVisitor);
eliminate(consumerp, vvertexp->varScp(), dupVarRefp, &m_varVisitor);
}
outedgep = outedgep->relinkFromp(dupVvertexp);
}
@ -1571,12 +1552,13 @@ void GateVisitor::decomposeClkVectors() {
}
//######################################################################
// Convert VARSCOPE(ASSIGN(default, VARREF)) to just VARSCOPE(default)
// Gate class functions
class GateDeassignVisitor final : public GateBaseVisitor {
private:
// VISITORS
virtual void visit(AstVarScope* nodep) override {
void V3Gate::gateAll(AstNetlist* nodep) {
UINFO(2, __FUNCTION__ << ": " << endl);
{ const GateVisitor visitor{nodep}; } // Destruct before checking
nodep->foreach<AstVarScope>([](AstVarScope* nodep) {
if (AstNodeAssign* const assp = VN_CAST(nodep->valuep(), NodeAssign)) {
UINFO(5, " Removeassign " << assp << endl);
AstNode* const valuep = assp->rhsp();
@ -1584,26 +1566,7 @@ private:
assp->replaceWith(valuep);
VL_DO_DANGLING(assp->deleteTree(), assp);
}
}
// Speedups
virtual void visit(AstVar*) override {} // Accelerate
virtual void visit(AstActive*) override {} // Accelerate
virtual void visit(AstNode* nodep) override { iterateChildren(nodep); }
});
public:
// CONSTRUCTORS
explicit GateDeassignVisitor(AstNode* nodep) { iterate(nodep); }
virtual ~GateDeassignVisitor() override = default;
};
//######################################################################
// Gate class functions
void V3Gate::gateAll(AstNetlist* nodep) {
UINFO(2, __FUNCTION__ << ": " << endl);
{
const GateVisitor visitor{nodep};
GateDeassignVisitor{nodep};
} // Destruct before checking
V3Global::dumpCheckGlobalTree("gate", 0, v3Global.opt.dumpTreeLevel(__FILE__) >= 3);
}