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verilator/src/V3Timing.cpp

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// -*- mode: C++; c-file-style: "cc-mode" -*-
//*************************************************************************
// DESCRIPTION: Verilator: Prepare AST for timing features
//
// Code available from: https://verilator.org
//
//*************************************************************************
//
// Copyright 2003-2023 by Wilson Snyder. This program is free software; you
// can redistribute it and/or modify it under the terms of either the GNU
// Lesser General Public License Version 3 or the Perl Artistic License
// Version 2.0.
// SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
//
// TimingSuspendableVisitor does not perform any AST transformations.
// Instead it propagates two types of flags:
// - flag "suspendable": (for detecting what will need to become a coroutine)
// The visitor locates all C++ functions and processes that contain timing controls,
// and marks them as suspendable. If a process calls a suspendable function,
// then it is also marked as suspendable. If a function calls or overrides
// a suspendable function, it is also marked as suspendable.
// TimingSuspendableVisitor creates a dependency graph to propagate this property.
// - flag "needs process": (for detecting what needs a VlProcess argument in signature)
// The visitor distinguishes 4 types of nodes:
// - T_ALLOCS_PROC: nodes that can allocate VlProcess (forks, always, initial etc.),
// - T_FORCES_PROC: nodes that make it necessary for the previous type to allocate VlProcess
// (like process::self which then wraps it, allowing use inside Verilog).
// - T_NEEDS_PROC: nodes that should obtain VlProcess if it will be allocated
// (all of the previous type + timing controls, so they could update process state),
// - T_HAS_PROC: nodes that are going to be emitted with a VlProcess argument.
// T_FORCES_PROC and T_NEEDS_PROC are propagated upwards up to the nodes of type T_ALLOCS_PROC,
// this is to detect which processes have to allocate VlProcess. Then nodes of these processes
// get marked as T_HAS_PROC and the flag is propagated downwards through nodes
// type T_NEEDS_PROC. Using only nodes type T_NEEDS_PROC assures the flags are only propagated
// through paths leading to nodes that actually use VlProcess.
//
// TimingControlVisitor is the one that actually performs transformations:
// - for each intra-assignment timing control:
// - if it's a continuous assignment, transform it into an always
// - introduce an intermediate variable
// - write the original RHS to the intermediate variable before the timing control
// - write the intermediate variable to the original LHS after the timing control
// - for each delay:
// - scale it according to the module's timescale
// - replace it with a CAwait statement waiting on the global delay scheduler (with the
// specified delay value)
// - if there is no global delay scheduler (see verilated_timing.{h,cpp}), create it
// - for each event control:
// - if there is no corresponding trigger scheduler (see verilated_timing.{h,cpp}), create it
// - replace with a CAwait statement waiting on the corresponding trigger scheduler
// - for each wait(cond) statement:
// - replace it with a loop like: while (!cond) @(<vars from cond>)
// - for each fork:
// - put each statement in a begin if it isn't in one already
// - if it's not a fork..join_none:
// - create a join sync variable
// - create statements that sync the main process with its children
//
// See the internals documentation docs/internals.rst for more details.
//
//*************************************************************************
#include "V3PchAstNoMT.h" // VL_MT_DISABLED_CODE_UNIT
#include "V3Timing.h"
#include "V3Const.h"
#include "V3EmitV.h"
#include "V3Graph.h"
#include "V3MemberMap.h"
#include "V3SenExprBuilder.h"
#include "V3SenTree.h"
#include "V3UniqueNames.h"
#include <queue>
VL_DEFINE_DEBUG_FUNCTIONS;
// ######################################################################
enum NodeFlag : uint8_t {
T_SUSPENDEE = 1 << 0, // Suspendable (due to dependence on another suspendable)
T_SUSPENDER = 1 << 1, // Suspendable (has timing control)
T_ALLOCS_PROC = 1 << 2, // Can allocate VlProcess
T_FORCES_PROC = 1 << 3, // Forces VlProcess allocation
T_NEEDS_PROC = 1 << 4, // Needs access to VlProcess if it's allocated
T_HAS_PROC = 1 << 5, // Has VlProcess argument in the signature
};
enum ForkType : uint8_t {
F_NONE = 0, // Not under a fork
F_MIGHT_SUSPEND = 1 << 0, // Fork might suspend the execution of current process
F_MIGHT_NEED_PROC = 1 << 1, // Fork might need a process (any fork really)
};
enum PropagationType : uint8_t {
P_CALL = 1, // Propagation through call to a function/task/method
P_FORK = 2, // Propagation due to fork's behaviour
P_SIGNATURE = 3, // Propagation required to maintain C++ function's signature requirements
};
// Add timing flag to a node
static void addFlags(AstNode* const nodep, uint8_t flags) { nodep->user2(nodep->user2() | flags); }
// Check if a node has ALL of the expected flags set
static bool hasFlags(AstNode* const nodep, uint8_t flags) { return !(~nodep->user2() & flags); }
// ######################################################################
// Detect nodes affected by timing and/or requiring a process
class TimingSuspendableVisitor final : public VNVisitor {
private:
// TYPES
// Vertex of a dependency graph of suspendable nodes, e.g. if a node (process or task) is
// suspendable, all its dependents should also be suspendable
class DepVtx VL_NOT_FINAL : public V3GraphVertex {
VL_RTTI_IMPL(DepVtx, V3GraphVertex)
AstClass* const m_classp; // Class associated with a method
AstNode* const m_nodep; // AST node represented by this graph vertex
// ACCESSORS
string name() const override {
if (m_classp) {
if (VN_IS(nodep(), CFunc)) {
return cvtToHex(nodep()) + ' ' + classp()->name() + "::" + nodep()->name();
}
}
return cvtToHex(nodep()) + ' ' + nodep()->prettyTypeName();
}
FileLine* fileline() const override { return nodep()->fileline(); }
public:
// CONSTRUCTORS
DepVtx(V3Graph* graphp, AstNode* nodep, AstClass* classp)
: V3GraphVertex{graphp}
, m_classp{classp}
, m_nodep{nodep} {}
~DepVtx() override = default;
// ACCESSORS
virtual AstNode* nodep() const VL_MT_STABLE { return m_nodep; }
virtual AstNode* classp() const VL_MT_STABLE { return m_classp; }
};
class SuspendDepVtx final : public DepVtx {
VL_RTTI_IMPL(SuspendDepVtx, DepVtx)
string dotColor() const override {
if (hasFlags(nodep(), T_SUSPENDER)) return "red";
if (hasFlags(nodep(), T_SUSPENDEE)) return "blue";
return "black";
}
public:
SuspendDepVtx(V3Graph* graphp, AstNode* nodep, AstClass* classp)
: DepVtx{graphp, nodep, classp} {}
~SuspendDepVtx() override = default;
};
class NeedsProcDepVtx final : public DepVtx {
VL_RTTI_IMPL(NeedsProcDepVtx, DepVtx)
string dotColor() const override {
if (hasFlags(nodep(), T_HAS_PROC)) return "blue";
if (hasFlags(nodep(), T_NEEDS_PROC)) return "green";
if (hasFlags(nodep(), T_FORCES_PROC)) return "red";
return "black";
}
public:
NeedsProcDepVtx(V3Graph* graphp, AstNode* nodep, AstClass* classp)
: DepVtx{graphp, nodep, classp} {}
~NeedsProcDepVtx() override = default;
};
// NODE STATE
// AstClass::user1() -> bool. Set true if the class
// member cache has been
// refreshed.
// Ast{NodeProcedure,CFunc,Begin}::user2() -> int. Set to >= T_SUSP if
// process/task suspendable
// and to T_PROC if it
// needs process metadata.
// Ast{NodeProcedure,CFunc,Begin}::user3() -> DependencyVertex*. Vertex in m_suspGraph
// Ast{NodeProcedure,CFunc,Begin}::user3() -> DependencyVertex*. Vertex in m_procGraph
const VNUser1InUse m_user1InUse;
const VNUser2InUse m_user2InUse;
const VNUser3InUse m_user3InUse;
const VNUser4InUse m_user4InUse;
// STATE
VMemberMap m_memberMap; // Member names cached for fast lookup
AstClass* m_classp = nullptr; // Current class
AstNode* m_procp = nullptr; // NodeProcedure/CFunc/Begin we're under
uint8_t m_underFork = F_NONE; // F_NONE or flags of a fork we are under
V3Graph m_suspGraph; // Dependency graph where a node is a dependency of another if it being
// suspendable makes the other node suspendable
V3Graph m_procGraph; // Dependency graph where a node is a dependency of another if it being
// suspendable makes the other node suspendable
// METHODS
// Get or create the dependency vertex for the given node
DepVtx* getSuspendDepVtx(AstNode* const nodep) {
AstClass* classp = nullptr;
if (AstCFunc* funcp = VN_CAST(nodep, CFunc)) {
if (funcp->scopep() && funcp->scopep()->modp()) {
classp = VN_CAST(funcp->scopep()->modp(), Class);
}
}
if (!nodep->user3p()) nodep->user3p(new SuspendDepVtx{&m_suspGraph, nodep, classp});
return nodep->user3u().to<SuspendDepVtx*>();
}
DepVtx* getNeedsProcDepVtx(AstNode* const nodep) {
AstClass* classp = nullptr;
if (AstCFunc* funcp = VN_CAST(nodep, CFunc)) {
if (funcp->scopep() && funcp->scopep()->modp()) {
classp = VN_CAST(funcp->scopep()->modp(), Class);
}
}
if (!nodep->user4p()) nodep->user4p(new NeedsProcDepVtx{&m_procGraph, nodep, classp});
return nodep->user4u().to<NeedsProcDepVtx*>();
}
// Pass timing flag between nodes
bool passFlag(const AstNode* from, AstNode* to, NodeFlag flag) {
if ((from->user2() & flag) && !(to->user2() & flag)) {
addFlags(to, flag);
return true;
}
return false;
}
// Propagate flag to all nodes that depend on the given one
void propagateFlags(DepVtx* const vxp, NodeFlag flag) {
auto* const parentp = vxp->nodep();
for (V3GraphEdge* edgep = vxp->outBeginp(); edgep; edgep = edgep->outNextp()) {
auto* const depVxp = static_cast<DepVtx*>(edgep->top());
AstNode* const depp = depVxp->nodep();
if (passFlag(parentp, depp, flag)) propagateFlags(depVxp, flag);
}
}
template <typename Predicate>
void propagateFlagsIf(DepVtx* const vxp, NodeFlag flag, Predicate p) {
auto* const parentp = vxp->nodep();
for (V3GraphEdge* edgep = vxp->outBeginp(); edgep; edgep = edgep->outNextp()) {
auto* const depVxp = static_cast<DepVtx*>(edgep->top());
AstNode* const depp = depVxp->nodep();
if (p(edgep) && passFlag(parentp, depp, flag)) propagateFlagsIf(depVxp, flag, p);
}
}
template <typename Predicate>
void propagateFlagsReversedIf(DepVtx* const vxp, NodeFlag flag, Predicate p) {
auto* const parentp = vxp->nodep();
for (V3GraphEdge* edgep = vxp->inBeginp(); edgep; edgep = edgep->inNextp()) {
auto* const depVxp = static_cast<DepVtx*>(edgep->fromp());
AstNode* const depp = depVxp->nodep();
if (p(edgep) && passFlag(parentp, depp, flag))
propagateFlagsReversedIf(depVxp, flag, p);
}
}
// VISITORS
void visit(AstClass* nodep) override {
UASSERT(!m_classp, "Class under class");
VL_RESTORER(m_classp);
m_classp = nodep;
iterateChildren(nodep);
}
void visit(AstNodeProcedure* nodep) override {
VL_RESTORER(m_procp);
m_procp = nodep;
getNeedsProcDepVtx(nodep);
addFlags(nodep, T_ALLOCS_PROC);
if (VN_IS(nodep, Always)) {
UINFO(1, "Always does " << (nodep->needProcess() ? "" : "NOT ") << "need process\n");
}
iterateChildren(nodep);
}
void visit(AstDisableFork* nodep) override {
visit(static_cast<AstNode*>(nodep));
addFlags(m_procp, T_FORCES_PROC | T_NEEDS_PROC);
}
void visit(AstWaitFork* nodep) override {
visit(static_cast<AstNode*>(nodep));
addFlags(m_procp, T_FORCES_PROC | T_NEEDS_PROC);
}
void visit(AstWait* nodep) override {
AstNodeExpr* const condp = V3Const::constifyEdit(nodep->condp());
if (AstConst* const constp = VN_CAST(condp, Const)) {
if (!nodep->fileline()->warnIsOff(V3ErrorCode::WAITCONST)) {
condp->v3warn(WAITCONST, "Wait statement condition is constant");
}
if (!constp->isZero()) {
// Remove AstWait before we track process as T_SUSPENDER
if (AstNode* const stmtsp = nodep->stmtsp()) {
stmtsp->unlinkFrBackWithNext();
nodep->replaceWith(stmtsp);
} else {
nodep->unlinkFrBack();
}
VL_DO_DANGLING(pushDeletep(nodep), nodep);
return;
}
}
v3Global.setUsesTiming();
if (m_procp) addFlags(m_procp, T_SUSPENDEE | T_SUSPENDER | T_NEEDS_PROC);
iterateChildren(nodep);
}
void visit(AstCFunc* nodep) override {
VL_RESTORER(m_procp);
m_procp = nodep;
iterateChildren(nodep);
if (nodep->needProcess()) addFlags(nodep, T_FORCES_PROC | T_NEEDS_PROC);
DepVtx* const sVxp = getSuspendDepVtx(nodep);
DepVtx* const pVxp = getNeedsProcDepVtx(nodep);
if (!m_classp) return;
// Go over overridden functions
std::queue<AstClassExtends*> extends;
if (m_classp->extendsp()) extends.push(m_classp->extendsp());
while (!extends.empty()) {
AstClassExtends* ext_list = extends.front();
extends.pop();
for (AstClassExtends* cextp = ext_list; cextp;
cextp = VN_AS(cextp->nextp(), ClassExtends)) {
// TODO: It is possible that a methods the same name in the base class is not
// actually overridden by our method. If this causes a problem, traverse to
// the root of the inheritance hierarchy and check if the original method is
// virtual or not.
if (auto* const overriddenp
= VN_CAST(m_memberMap.findMember(cextp->classp(), nodep->name()), CFunc)) {
// Suspendability and process affects typing, so they propagate both ways
DepVtx* const overriddenSVxp = getSuspendDepVtx(overriddenp);
DepVtx* const overriddenPVxp = getNeedsProcDepVtx(overriddenp);
new V3GraphEdge{&m_suspGraph, sVxp, overriddenSVxp, P_SIGNATURE};
new V3GraphEdge{&m_suspGraph, overriddenSVxp, sVxp, P_SIGNATURE};
new V3GraphEdge{&m_procGraph, pVxp, overriddenPVxp, P_SIGNATURE};
new V3GraphEdge{&m_procGraph, overriddenPVxp, pVxp, P_SIGNATURE};
} else {
AstClassExtends* more_extends = cextp->classp()->extendsp();
if (more_extends) extends.push(more_extends);
}
}
}
}
void visit(AstNodeCCall* nodep) override {
if (!m_underFork || (m_underFork & F_MIGHT_SUSPEND))
new V3GraphEdge{&m_suspGraph, getSuspendDepVtx(nodep->funcp()),
getSuspendDepVtx(m_procp), m_underFork ? P_FORK : P_CALL};
new V3GraphEdge{&m_procGraph, getNeedsProcDepVtx(nodep->funcp()),
getNeedsProcDepVtx(m_procp), P_CALL};
if (m_underFork && !(m_underFork & F_MIGHT_SUSPEND)) {
addFlags(nodep, T_NEEDS_PROC | T_ALLOCS_PROC);
}
iterateChildren(nodep);
}
void visit(AstBegin* nodep) override {
VL_RESTORER(m_procp);
VL_RESTORER(m_underFork);
if (!m_underFork || (m_underFork & F_MIGHT_SUSPEND))
new V3GraphEdge{&m_suspGraph, getSuspendDepVtx(nodep), getSuspendDepVtx(m_procp),
m_underFork ? P_FORK : P_CALL};
new V3GraphEdge{&m_procGraph, getNeedsProcDepVtx(nodep), getNeedsProcDepVtx(m_procp),
P_CALL};
if (m_underFork && !(m_underFork & F_MIGHT_SUSPEND)) {
addFlags(nodep, T_NEEDS_PROC | T_ALLOCS_PROC);
}
m_procp = nodep;
m_underFork = 0;
iterateChildren(nodep);
}
void visit(AstFork* nodep) override {
VL_RESTORER(m_underFork);
v3Global.setUsesTiming(); // Even if there are no event controls, we have to set this flag
// so that transformForks() in V3SchedTiming gets called and
// removes all forks and begins
if (nodep->isTimingControl() && m_procp) {
addFlags(m_procp, T_SUSPENDEE | T_SUSPENDER);
m_underFork |= F_MIGHT_SUSPEND;
}
m_underFork |= F_MIGHT_NEED_PROC;
iterateChildren(nodep);
}
void visit(AstAssignDly* nodep) override {
if (!VN_IS(m_procp, NodeProcedure)) v3Global.setUsesTiming();
visit(static_cast<AstNode*>(nodep));
}
void visit(AstNode* nodep) override {
if (nodep->isTimingControl()) {
v3Global.setUsesTiming();
if (m_procp) addFlags(m_procp, T_SUSPENDEE | T_SUSPENDER | T_NEEDS_PROC);
}
iterateChildren(nodep);
}
//--------------------
void visit(AstVar*) override {} // Accelerate
public:
// CONSTRUCTORS
explicit TimingSuspendableVisitor(AstNetlist* nodep) {
iterate(nodep);
m_suspGraph.removeTransitiveEdges();
m_procGraph.removeTransitiveEdges();
// Propagate suspendability
for (V3GraphVertex* vxp = m_suspGraph.verticesBeginp(); vxp; vxp = vxp->verticesNextp()) {
DepVtx* const depVxp = static_cast<DepVtx*>(vxp);
if (hasFlags(depVxp->nodep(), T_SUSPENDEE)) propagateFlags(depVxp, T_SUSPENDEE);
}
if (dumpGraphLevel() >= 6) m_suspGraph.dumpDotFilePrefixed("timing_deps");
// Propagate T_HAS_PROCESS
for (V3GraphVertex* vxp = m_procGraph.verticesBeginp(); vxp; vxp = vxp->verticesNextp()) {
DepVtx* const depVxp = static_cast<DepVtx*>(vxp);
// Find processes that'll allocate VlProcess
if (hasFlags(depVxp->nodep(), T_FORCES_PROC)) {
propagateFlagsIf(depVxp, T_FORCES_PROC, [&](const V3GraphEdge* e) -> bool {
return !hasFlags(static_cast<DepVtx*>(e->fromp())->nodep(), T_ALLOCS_PROC);
});
}
// Mark nodes on paths between processes and statements that use VlProcess
if (hasFlags(depVxp->nodep(), T_NEEDS_PROC)) {
propagateFlagsIf(depVxp, T_NEEDS_PROC, [&](const V3GraphEdge* e) -> bool {
return !hasFlags(static_cast<DepVtx*>(e->top())->nodep(), T_ALLOCS_PROC);
});
}
}
for (V3GraphVertex* vxp = m_procGraph.verticesBeginp(); vxp; vxp = vxp->verticesNextp()) {
DepVtx* const depVxp = static_cast<DepVtx*>(vxp);
// Mark nodes that will be emitted with a VlProcess argument
if (hasFlags(depVxp->nodep(), T_ALLOCS_PROC | T_FORCES_PROC)) {
addFlags(depVxp->nodep(), T_HAS_PROC);
propagateFlagsReversedIf(depVxp, T_HAS_PROC, [&](const V3GraphEdge* e) -> bool {
return hasFlags(static_cast<DepVtx*>(e->fromp())->nodep(), T_NEEDS_PROC);
});
}
}
if (dumpGraphLevel() >= 6) m_procGraph.dumpDotFilePrefixed("proc_deps");
}
~TimingSuspendableVisitor() override = default;
};
// ######################################################################
// Transform nodes affected by timing
class TimingControlVisitor final : public VNVisitor {
private:
// NODE STATE
// Ast{Always,NodeCCall,Fork,NodeAssign}::user1() -> bool. Set true if the node has
// been processed.
// AstSenTree::user1() -> AstVarScope*. Trigger scheduler assigned
// to this sentree
// Ast{NodeProcedure,CFunc,Begin}::user2() -> bool. Set true if process/task
// is suspendable
// Ast{EventControl}::user2() -> bool. Set true if event control
// should immediately be
// committed
// AstSenTree::user2() -> AstCExpr*. Debug info passed to the
// timing schedulers
// const VNUser1InUse m_user1InUse; (Allocated for use in SuspendableVisitor)
// const VNUser2InUse m_user2InUse; (Allocated for use in SuspendableVisitor)
// STATE
// Current context
AstNetlist* const m_netlistp; // Root node
AstScope* const m_scopeTopp = m_netlistp->topScopep()->scopep(); // Scope at the top
AstClass* m_classp = nullptr; // Current class
AstScope* m_scopep = nullptr; // Current scope
AstActive* m_activep = nullptr; // Current active
AstNode* m_procp = nullptr; // NodeProcedure/CFunc/Begin we're under
double m_timescaleFactor = 1.0; // Factor to scale delays by
int m_forkCnt = 0; // Number of forks inside a module
bool m_underJumpBlock = false; // True if we are inside of a jump-block
bool m_underProcedure = false; // True if we are under an always or initial
// Unique names
V3UniqueNames m_dlyforkNames{"__Vdlyfork"}; // Names for temp AssignW vars
V3UniqueNames m_contAssignVarNames{"__VassignWtmp"}; // Names for temp AssignW vars
V3UniqueNames m_intraValueNames{"__Vintraval"}; // Intra assign delay value var names
V3UniqueNames m_intraIndexNames{"__Vintraidx"}; // Intra assign delay index var names
V3UniqueNames m_intraLsbNames{"__Vintralsb"}; // Intra assign delay LSB var names
V3UniqueNames m_trigSchedNames{"__VtrigSched"}; // Trigger scheduler name generator
V3UniqueNames m_dynTrigNames{"__VdynTrigger"}; // Dynamic trigger name generator
// DTypes
AstBasicDType* m_forkDtp = nullptr; // Fork variable type
AstBasicDType* m_trigSchedDtp = nullptr; // Trigger scheduler type
// Timing-related globals
AstVarScope* m_delaySchedp = nullptr; // Global delay scheduler
AstVarScope* m_dynamicSchedp = nullptr; // Global dynamic trigger scheduler
AstSenTree* m_delaySensesp = nullptr; // Domain to trigger if a delayed coroutine is resumed
AstSenTree* m_dynamicSensesp = nullptr; // Domain to trigger if a dynamic trigger is set
// Other
SenTreeFinder m_finder{m_netlistp}; // Sentree finder and uniquifier
SenExprBuilder* m_senExprBuilderp = nullptr; // Sens expression builder for current m_scope
// METHODS
// Find net delay on the LHS of an assignment
AstDelay* getLhsNetDelayRecurse(const AstNodeExpr* const nodep) const {
if (const AstNodeVarRef* const refp = VN_CAST(nodep, NodeVarRef)) {
if (refp->varp()->delayp()) return refp->varp()->delayp()->unlinkFrBack();
} else if (const AstSel* const selp = VN_CAST(nodep, Sel)) {
return getLhsNetDelayRecurse(selp->fromp());
}
return nullptr;
}
// Transform an assignment with an intra timing control into a timing control with the
// assignment under it
AstNode* factorOutTimingControl(AstNodeAssign* nodep) const {
AstNode* stmtp = nodep;
AstDelay* delayp = getLhsNetDelayRecurse(nodep->lhsp());
FileLine* const flp = nodep->fileline();
AstNode* const controlp = nodep->timingControlp();
if (controlp) {
controlp->unlinkFrBack();
if (auto* const assignDelayp = VN_CAST(controlp, Delay)) {
if (delayp) {
delayp->lhsp(new AstAdd{flp, delayp->lhsp()->unlinkFrBack(),
assignDelayp->lhsp()->unlinkFrBack()});
VL_DO_DANGLING(assignDelayp->deleteTree(), nodep);
} else {
delayp = assignDelayp;
}
}
}
if (delayp) {
stmtp->replaceWith(delayp);
delayp->addStmtsp(stmtp);
stmtp = delayp;
}
if (auto* const sensesp = VN_CAST(controlp, SenTree)) {
auto* const eventControlp = new AstEventControl{flp, sensesp, nullptr};
stmtp->replaceWith(eventControlp);
eventControlp->addStmtsp(stmtp);
stmtp = eventControlp;
} else if (auto* const beginp = VN_CAST(controlp, Begin)) {
// Begin from V3AssertPre
stmtp->replaceWith(beginp);
beginp->addStmtsp(stmtp);
stmtp = beginp;
}
return stmtp == nodep ? nullptr : stmtp;
}
// Calculate the factor to scale delays by
double calculateTimescaleFactor(VTimescale timeunit) const {
int scalePowerOfTen = timeunit.powerOfTen() - m_netlistp->timeprecision().powerOfTen();
return std::pow(10.0, scalePowerOfTen);
}
// Creates the global delay scheduler variable
AstVarScope* getCreateDelayScheduler() {
if (m_delaySchedp) return m_delaySchedp;
auto* const dlySchedDtp = new AstBasicDType{
m_scopeTopp->fileline(), VBasicDTypeKwd::DELAY_SCHEDULER, VSigning::UNSIGNED};
m_netlistp->typeTablep()->addTypesp(dlySchedDtp);
m_delaySchedp = m_scopeTopp->createTemp("__VdlySched", dlySchedDtp);
// Delay scheduler has to be accessible from top
m_delaySchedp->varp()->sigPublic(true);
m_netlistp->delaySchedulerp(m_delaySchedp->varp());
return m_delaySchedp;
}
// Creates the delay sentree
AstSenTree* getCreateDelaySenTree() {
if (m_delaySensesp) return m_delaySensesp;
FileLine* const flp = m_scopeTopp->fileline();
auto* const awaitingCurrentTimep
= new AstCMethodHard{flp, new AstVarRef{flp, getCreateDelayScheduler(), VAccess::READ},
"awaitingCurrentTime"};
awaitingCurrentTimep->dtypeSetBit();
m_delaySensesp
= new AstSenTree{flp, new AstSenItem{flp, VEdgeType::ET_TRUE, awaitingCurrentTimep}};
m_netlistp->topScopep()->addSenTreesp(m_delaySensesp);
return m_delaySensesp;
}
// Creates the global dynamic trigger scheduler variable
AstVarScope* getCreateDynamicTriggerScheduler() {
if (m_dynamicSchedp) return m_dynamicSchedp;
auto* const dynSchedDtp
= new AstBasicDType{m_scopeTopp->fileline(), VBasicDTypeKwd::DYNAMIC_TRIGGER_SCHEDULER,
VSigning::UNSIGNED};
m_netlistp->typeTablep()->addTypesp(dynSchedDtp);
m_dynamicSchedp = m_scopeTopp->createTemp("__VdynSched", dynSchedDtp);
return m_dynamicSchedp;
}
// Creates the dynamic trigger sentree
AstSenTree* getCreateDynamicTriggerSenTree() {
if (m_dynamicSensesp) return m_dynamicSensesp;
FileLine* const flp = m_scopeTopp->fileline();
auto* const awaitingCurrentTimep = new AstCMethodHard{
flp, new AstVarRef{flp, getCreateDynamicTriggerScheduler(), VAccess::READ},
"evaluate"};
awaitingCurrentTimep->dtypeSetBit();
m_dynamicSensesp
= new AstSenTree{flp, new AstSenItem{flp, VEdgeType::ET_TRUE, awaitingCurrentTimep}};
m_netlistp->topScopep()->addSenTreesp(m_dynamicSensesp);
return m_dynamicSensesp;
}
// Creates the event variable to trigger in NBA region
AstEventControl* createNbaEventControl(FileLine* flp) {
if (!m_netlistp->nbaEventp()) {
auto* const nbaEventDtp = new AstBasicDType{m_scopeTopp->fileline(),
VBasicDTypeKwd::EVENT, VSigning::UNSIGNED};
m_netlistp->typeTablep()->addTypesp(nbaEventDtp);
m_netlistp->nbaEventp(m_scopeTopp->createTemp("__VnbaEvent", nbaEventDtp));
v3Global.setHasEvents();
}
return new AstEventControl{
flp,
new AstSenTree{
flp, new AstSenItem{flp, VEdgeType::ET_EVENT,
new AstVarRef{flp, m_netlistp->nbaEventp(), VAccess::READ}}},
nullptr};
}
// Creates the variable that, if set, causes the NBA event to be triggered
AstAssign* createNbaEventTriggerAssignment(FileLine* flp) {
if (!m_netlistp->nbaEventTriggerp()) {
m_netlistp->nbaEventTriggerp(m_scopeTopp->createTemp("__VnbaEventTrigger", 1));
}
return new AstAssign{flp,
new AstVarRef{flp, m_netlistp->nbaEventTriggerp(), VAccess::WRITE},
new AstConst{flp, AstConst::BitTrue{}}};
}
// Returns true if we are under a class or the given tree has any references to locals. These
// are cases where static, globally-evaluated triggers are not suitable.
bool needDynamicTrigger(AstNode* const nodep) const {
return m_classp || nodep->exists([](AstNode* const nodep) {
if (AstNodeVarRef* varp = VN_CAST(nodep, NodeVarRef)) {
return varp->varp()->isFuncLocal();
}
return !nodep->isPure();
});
}
// Returns true if the given trigger expression needs a destructive post update after trigger
// evaluation. Currently this only applies to named events.
bool destructivePostUpdate(AstNode* const exprp) const {
return exprp->exists([](const AstNodeVarRef* const refp) {
AstBasicDType* const dtypep = refp->dtypep()->basicp();
return dtypep && dtypep->isEvent();
});
}
// Creates a trigger scheduler variable
AstVarScope* getCreateTriggerSchedulerp(AstSenTree* const sensesp) {
if (!sensesp->user1p()) {
if (!m_trigSchedDtp) {
m_trigSchedDtp
= new AstBasicDType{m_scopeTopp->fileline(), VBasicDTypeKwd::TRIGGER_SCHEDULER,
VSigning::UNSIGNED};
m_netlistp->typeTablep()->addTypesp(m_trigSchedDtp);
}
AstVarScope* const trigSchedp
= m_scopeTopp->createTemp(m_trigSchedNames.get(sensesp), m_trigSchedDtp);
sensesp->user1p(trigSchedp);
}
return VN_AS(sensesp->user1p(), VarScope);
}
// Creates a string describing the sentree
AstCExpr* createEventDescription(AstSenTree* const sensesp) const {
if (!sensesp->user2p()) {
std::stringstream ss;
ss << '"';
V3EmitV::verilogForTree(sensesp, ss);
ss << '"';
// possibly a multiline string
std::string comment = ss.str();
std::replace(comment.begin(), comment.end(), '\n', ' ');
AstCExpr* const commentp = new AstCExpr{sensesp->fileline(), comment, 0};
commentp->dtypeSetString();
sensesp->user2p(commentp);
return commentp;
}
return VN_AS(sensesp->user2p(), CExpr)->cloneTree(false);
}
// Adds debug info to a hardcoded method call
void addDebugInfo(AstCMethodHard* const methodp) const {
if (v3Global.opt.protectIds()) return;
FileLine* const flp = methodp->fileline();
AstCExpr* const ap = new AstCExpr{flp, '"' + flp->filename() + '"', 0};
ap->dtypeSetString();
methodp->addPinsp(ap);
AstCExpr* const bp = new AstCExpr{flp, cvtToStr(flp->lineno()), 0};
bp->dtypeSetString();
methodp->addPinsp(bp);
}
// Adds debug info to a trigSched.trigger() call
void addEventDebugInfo(AstCMethodHard* const methodp, AstSenTree* const sensesp) const {
if (v3Global.opt.protectIds()) return;
methodp->addPinsp(createEventDescription(sensesp));
addDebugInfo(methodp);
}
// Adds process pointer to a hardcoded method call
void addProcessInfo(AstCMethodHard* const methodp) const {
FileLine* const flp = methodp->fileline();
AstCExpr* const ap = new AstCExpr{
flp, m_procp && (hasFlags(m_procp, T_HAS_PROC)) ? "vlProcess" : "nullptr", 0};
ap->dtypeSetVoid();
methodp->addPinsp(ap);
}
// Creates the fork handle type and returns it
AstBasicDType* getCreateForkSyncDTypep() {
if (m_forkDtp) return m_forkDtp;
m_forkDtp = new AstBasicDType{m_scopeTopp->fileline(), VBasicDTypeKwd::FORK_SYNC,
VSigning::UNSIGNED};
m_netlistp->typeTablep()->addTypesp(m_forkDtp);
return m_forkDtp;
}
// Move `insertBeforep` into `AstCLocalScope` if necessary to avoid jumping over
// a variable initialization that whould be inserted before `insertBeforep`. All
// access to this variable shoule be contained within returned `AstCLocalScope`.
AstCLocalScope* addCLocalScope(FileLine* const flp, AstNode* const insertBeforep) const {
if (!insertBeforep || !m_underJumpBlock) return nullptr;
VNRelinker handle;
insertBeforep->unlinkFrBack(&handle);
AstCLocalScope* const cscopep = new AstCLocalScope{flp, insertBeforep};
handle.relink(cscopep);
return cscopep;
}
// Create a temp variable and optionally put it before the specified node (mark local if so)
AstVarScope* createTemp(FileLine* const flp, const std::string& name,
AstNodeDType* const dtypep, AstNode* const insertBeforep = nullptr) {
AstVar* varp;
if (insertBeforep) {
varp = new AstVar{flp, VVarType::BLOCKTEMP, name, dtypep};
varp->funcLocal(true);
insertBeforep->addHereThisAsNext(varp);
} else {
varp = new AstVar{flp, VVarType::MODULETEMP, name, dtypep};
m_scopep->modp()->addStmtsp(varp);
}
AstVarScope* vscp = new AstVarScope{flp, m_scopep, varp};
m_scopep->addVarsp(vscp);
return vscp;
}
// Add a done() call on the fork sync
void addForkDone(AstBegin* const beginp, AstVarScope* const forkVscp) const {
FileLine* const flp = beginp->fileline();
auto* const donep = new AstCMethodHard{
beginp->fileline(), new AstVarRef{flp, forkVscp, VAccess::WRITE}, "done"};
donep->dtypeSetVoid();
addDebugInfo(donep);
beginp->addStmtsp(donep->makeStmt());
}
// Handle the 'join' part of a fork..join
void makeForkJoin(AstFork* const forkp) {
// Create a fork sync var
FileLine* const flp = forkp->fileline();
// If we're in a function, insert the sync var directly before the fork
AstNode* const insertBeforep = m_classp ? forkp : nullptr;
addCLocalScope(flp, insertBeforep);
AstVarScope* forkVscp
= createTemp(flp, forkp->name() + "__sync", getCreateForkSyncDTypep(), insertBeforep);
unsigned joinCount = 0; // Needed for join counter
// Add a <fork sync>.done() to each begin
for (AstNode* beginp = forkp->stmtsp(); beginp; beginp = beginp->nextp()) {
addForkDone(VN_AS(beginp, Begin), forkVscp);
joinCount++;
}
if (forkp->joinType().joinAny()) joinCount = 1;
// Set the join counter
auto* const initp = new AstCMethodHard{flp, new AstVarRef{flp, forkVscp, VAccess::WRITE},
"init", new AstConst{flp, joinCount}};
initp->dtypeSetVoid();
addProcessInfo(initp);
forkp->addHereThisAsNext(initp->makeStmt());
// Await the join at the end
auto* const joinp
= new AstCMethodHard{flp, new AstVarRef{flp, forkVscp, VAccess::WRITE}, "join"};
joinp->dtypeSetVoid();
addProcessInfo(joinp);
addDebugInfo(joinp);
AstCAwait* const awaitp = new AstCAwait{flp, joinp};
awaitp->dtypeSetVoid();
forkp->addNextHere(awaitp->makeStmt());
}
// VISITORS
void visit(AstNodeModule* nodep) override {
UASSERT(!m_classp, "Module or class under class");
VL_RESTORER(m_classp);
m_classp = VN_CAST(nodep, Class);
VL_RESTORER(m_timescaleFactor);
m_timescaleFactor = calculateTimescaleFactor(nodep->timeunit());
VL_RESTORER(m_forkCnt);
m_forkCnt = 0;
iterateChildren(nodep);
}
void visit(AstScope* nodep) override {
VL_RESTORER(m_scopep);
m_scopep = nodep;
SenExprBuilder senExprBuilder{m_scopep};
{ // Restore m_senExprBuilderp before destroying senExprBuilder
VL_RESTORER(m_senExprBuilderp);
m_senExprBuilderp = &senExprBuilder;
iterateChildren(nodep);
}
}
void visit(AstActive* nodep) override {
m_activep = nodep;
iterateChildren(nodep);
m_activep = nullptr;
}
void visit(AstNodeProcedure* nodep) override {
VL_RESTORER(m_procp);
m_procp = nodep;
VL_RESTORER(m_underProcedure);
m_underProcedure = true;
iterateChildren(nodep);
if (hasFlags(nodep, T_SUSPENDEE)) nodep->setSuspendable();
if (hasFlags(nodep, T_HAS_PROC)) nodep->setNeedProcess();
}
void visit(AstInitial* nodep) override {
visit(static_cast<AstNodeProcedure*>(nodep));
if (nodep->needProcess() && !nodep->user1SetOnce()) {
nodep->addStmtsp(
new AstCStmt{nodep->fileline(), "vlProcess->state(VlProcess::FINISHED);\n"});
}
}
void visit(AstJumpBlock* nodep) override {
VL_RESTORER(m_underJumpBlock);
m_underJumpBlock = true;
visit(static_cast<AstNodeStmt*>(nodep));
}
void visit(AstAlways* nodep) override {
if (nodep->user1SetOnce()) return;
VL_RESTORER(m_procp);
m_procp = nodep;
VL_RESTORER(m_underProcedure);
m_underProcedure = true;
// Workaround for killing `always` processes (doing that is pretty much UB)
// TODO: Disallow killing `always` at runtime (throw an error)
if (hasFlags(nodep, T_HAS_PROC)) addFlags(nodep, T_SUSPENDEE);
iterateChildren(nodep);
if (hasFlags(nodep, T_HAS_PROC)) nodep->setNeedProcess();
if (!hasFlags(nodep, T_SUSPENDEE)) return;
nodep->setSuspendable();
FileLine* const flp = nodep->fileline();
AstSenTree* const sensesp = m_activep->sensesp();
if (sensesp->hasClocked()) {
AstNode* const bodysp = nodep->stmtsp()->unlinkFrBackWithNext();
auto* const controlp = new AstEventControl{flp, sensesp->cloneTree(false), bodysp};
nodep->addStmtsp(controlp);
iterate(controlp);
}
// Note: The 'while (true)' outer loop will be added in V3Sched
auto* const activep = new AstActive{
flp, "", new AstSenTree{flp, new AstSenItem{flp, AstSenItem::Initial{}}}};
activep->sensesStorep(activep->sensesp());
activep->addStmtsp(nodep->unlinkFrBack());
m_activep->addNextHere(activep);
}
void visit(AstCFunc* nodep) override {
VL_RESTORER(m_procp);
m_procp = nodep;
iterateChildren(nodep);
if (hasFlags(nodep, T_HAS_PROC)) nodep->setNeedProcess();
if (!(hasFlags(nodep, T_SUSPENDEE))) return;
nodep->rtnType("VlCoroutine");
// If in a class, create a shared pointer to 'this'
if (m_classp) nodep->addInitsp(new AstCStmt{nodep->fileline(), "VL_KEEP_THIS;\n"});
AstNode* firstCoStmtp = nullptr; // First co_* statement in the function
nodep->exists([&](AstCAwait* const awaitp) -> bool { return (firstCoStmtp = awaitp); });
if (!firstCoStmtp) {
// It's a coroutine but has no awaits (a class method that overrides/is
// overridden by a suspendable, but doesn't have any awaits itself). Add a
// co_return at the end (either that or a co_await is required in a
// coroutine)
firstCoStmtp = new AstCStmt{nodep->fileline(), "co_return;\n"};
nodep->addStmtsp(firstCoStmtp);
}
if (nodep->dpiExportImpl()) {
// A DPI-exported coroutine won't be able to block the calling code
// Error on the await node; fall back to the function node
firstCoStmtp->v3warn(E_UNSUPPORTED,
"Unsupported: Timing controls inside DPI-exported tasks");
}
}
void visit(AstNodeCCall* nodep) override {
if (hasFlags(nodep->funcp(), T_SUSPENDEE) && !nodep->user1SetOnce()) { // If suspendable
VNRelinker relinker;
nodep->unlinkFrBack(&relinker);
AstCAwait* const awaitp = new AstCAwait{nodep->fileline(), nodep};
awaitp->dtypeSetVoid();
relinker.relink(awaitp);
}
iterateChildren(nodep);
}
void visit(AstDelay* nodep) override {
UASSERT_OBJ(!nodep->isCycleDelay(), nodep,
"Cycle delays should have been handled in V3AssertPre");
FileLine* const flp = nodep->fileline();
AstNodeExpr* valuep = V3Const::constifyEdit(nodep->lhsp()->unlinkFrBack());
auto* const constp = VN_CAST(valuep, Const);
if (constp && constp->isZero()) {
nodep->v3warn(ZERODLY, "Unsupported: #0 delays do not schedule process resumption in "
"the Inactive region");
} else {
// Scale the delay
if (valuep->dtypep()->isDouble()) {
valuep = new AstRToIRoundS{
flp,
new AstMulD{flp, valuep,
new AstConst{flp, AstConst::RealDouble{}, m_timescaleFactor}}};
valuep->dtypeSetBitSized(64, VSigning::UNSIGNED);
} else {
valuep->dtypeSetBitSized(64, VSigning::UNSIGNED);
valuep = new AstMul{flp, valuep,
new AstConst{flp, AstConst::Unsized64{},
static_cast<uint64_t>(m_timescaleFactor)}};
}
}
// Replace self with a 'co_await dlySched.delay(<valuep>)'
auto* const delayMethodp = new AstCMethodHard{
flp, new AstVarRef{flp, getCreateDelayScheduler(), VAccess::WRITE}, "delay", valuep};
delayMethodp->dtypeSetVoid();
addProcessInfo(delayMethodp);
addDebugInfo(delayMethodp);
// Create the co_await
AstCAwait* const awaitp = new AstCAwait{flp, delayMethodp, getCreateDelaySenTree()};
awaitp->dtypeSetVoid();
AstStmtExpr* const awaitStmtp = awaitp->makeStmt();
// Relink child statements after the co_await
if (nodep->stmtsp()) {
AstNode::addNext<AstNode, AstNode>(awaitStmtp,
nodep->stmtsp()->unlinkFrBackWithNext());
}
nodep->replaceWith(awaitStmtp);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
}
void visit(AstEventControl* nodep) override {
// Do not allow waiting on local named events, as they get enqueued for clearing, but can
// go out of scope before that happens
if (!nodep->sensesp()) nodep->v3warn(E_UNSUPPORTED, "Unsupported: no sense equation (@*)");
if (nodep->sensesp()->exists([](const AstNodeVarRef* refp) {
AstBasicDType* const dtypep = refp->dtypep()->skipRefp()->basicp();
return dtypep && dtypep->isEvent() && refp->varp()->isFuncLocal();
})) {
nodep->v3warn(E_UNSUPPORTED, "Unsupported: waiting on local event variables");
}
FileLine* const flp = nodep->fileline();
// Relink child statements after the event control
if (nodep->stmtsp()) nodep->addNextHere(nodep->stmtsp()->unlinkFrBackWithNext());
if (needDynamicTrigger(nodep->sensesp())) {
// Create the trigger variable and init it with 0
AstVarScope* const trigvscp
= createTemp(flp, m_dynTrigNames.get(nodep), nodep->findBitDType(), nodep);
auto* const initp = new AstAssign{flp, new AstVarRef{flp, trigvscp, VAccess::WRITE},
new AstConst{flp, AstConst::BitFalse{}}};
nodep->addHereThisAsNext(initp);
// Await the eval step with the dynamic trigger scheduler. First, create the method
// call
auto* const evalMethodp = new AstCMethodHard{
flp, new AstVarRef{flp, getCreateDynamicTriggerScheduler(), VAccess::WRITE},
"evaluation"};
evalMethodp->dtypeSetVoid();
addProcessInfo(evalMethodp);
auto* const sensesp = nodep->sensesp();
addEventDebugInfo(evalMethodp, sensesp);
// Create the co_await
AstCAwait* const awaitEvalp
= new AstCAwait{flp, evalMethodp, getCreateDynamicTriggerSenTree()};
awaitEvalp->dtypeSetVoid();
// Construct the sen expression for this sentree
UASSERT_OBJ(m_senExprBuilderp, nodep, "No SenExprBuilder for this scope");
auto* const assignp = new AstAssign{flp, new AstVarRef{flp, trigvscp, VAccess::WRITE},
m_senExprBuilderp->build(sensesp).first};
// Put all the locals and inits before the trigger eval loop
for (AstVar* const varp : m_senExprBuilderp->getAndClearLocals()) {
nodep->addHereThisAsNext(varp);
}
for (AstNodeStmt* const stmtp : m_senExprBuilderp->getAndClearInits()) {
nodep->addHereThisAsNext(stmtp);
}
// Create the trigger eval loop, which will await the evaluation step and check the
// trigger
AstWhile* const loopp = new AstWhile{
flp, new AstLogNot{flp, new AstVarRef{flp, trigvscp, VAccess::READ}},
awaitEvalp->makeStmt()};
// Put pre updates before the trigger check and assignment
for (AstNodeStmt* const stmtp : m_senExprBuilderp->getAndClearPreUpdates()) {
loopp->addStmtsp(stmtp);
}
// Then the trigger check and assignment
loopp->addStmtsp(assignp);
// Let the dynamic trigger scheduler know if this trigger was set
// If it was, a call to the scheduler's evaluate() will return true
AstCMethodHard* const anyTriggeredMethodp = new AstCMethodHard{
flp, new AstVarRef{flp, getCreateDynamicTriggerScheduler(), VAccess::WRITE},
"anyTriggered", new AstVarRef{flp, trigvscp, VAccess::READ}};
anyTriggeredMethodp->dtypeSetVoid();
loopp->addStmtsp(anyTriggeredMethodp->makeStmt());
// If the post update is destructive (e.g. event vars are cleared), create an await for
// the post update step
if (destructivePostUpdate(sensesp)) {
AstCAwait* const awaitPostUpdatep = awaitEvalp->cloneTree(false);
VN_AS(awaitPostUpdatep->exprp(), CMethodHard)->name("postUpdate");
loopp->addStmtsp(awaitPostUpdatep->makeStmt());
}
// Put the post updates at the end of the loop
for (AstNodeStmt* const stmtp : m_senExprBuilderp->getAndClearPostUpdates()) {
loopp->addStmtsp(stmtp);
}
// Finally, await the resumption step in 'act'
AstCAwait* const awaitResumep = awaitEvalp->cloneTree(false);
VN_AS(awaitResumep->exprp(), CMethodHard)->name("resumption");
AstNode::addNext<AstNodeStmt, AstNodeStmt>(loopp, awaitResumep->makeStmt());
// Replace the event control with the loop
nodep->replaceWith(loopp);
} else {
auto* const sensesp = m_finder.getSenTree(nodep->sensesp());
nodep->sensesp()->unlinkFrBack()->deleteTree();
// Get this sentree's trigger scheduler
// Replace self with a 'co_await trigSched.trigger()'
auto* const triggerMethodp = new AstCMethodHard{
flp, new AstVarRef{flp, getCreateTriggerSchedulerp(sensesp), VAccess::WRITE},
"trigger"};
triggerMethodp->dtypeSetVoid();
// If it should be committed immediately, pass true, otherwise false
triggerMethodp->addPinsp(nodep->user2() ? new AstConst{flp, AstConst::BitTrue{}}
: new AstConst{flp, AstConst::BitFalse{}});
addProcessInfo(triggerMethodp);
addEventDebugInfo(triggerMethodp, sensesp);
// Create the co_await
AstCAwait* const awaitp = new AstCAwait{flp, triggerMethodp, sensesp};
awaitp->dtypeSetVoid();
nodep->replaceWith(awaitp->makeStmt());
}
VL_DO_DANGLING(nodep->deleteTree(), nodep);
}
void visit(AstNodeAssign* nodep) override {
// Only process once to avoid infinite loops (due to the net delay)
if (nodep->user1SetOnce()) return;
FileLine* const flp = nodep->fileline();
AstNode* controlp = factorOutTimingControl(nodep);
const bool inAssignDly = VN_IS(nodep, AssignDly);
// Handle the intra assignment timing control
// Transform if:
// * there's a timing control in the assignment
// * the assignment is an AssignDly and it's in a non-inlined function
if (!controlp && (!inAssignDly || m_underProcedure)) return;
// Insert new vars before the timing control if we're in a function; in a process we can't
// do that. These intra-assignment vars will later be passed to forked processes by value.
AstNode* insertBeforep = m_underProcedure ? nullptr : controlp;
// Special case for NBA
if (inAssignDly) {
// Put it in a fork so it doesn't block
auto* const forkp = new AstFork{flp, "", nullptr};
forkp->joinType(VJoinType::JOIN_NONE);
if (!m_underProcedure) {
// If it's in a function, it won't be handled by V3Delayed
// Put it behind an additional named event that gets triggered in the NBA region
AstEventControl* const nbaEventControlp = createNbaEventControl(flp);
AstAssign* const trigAssignp = createNbaEventTriggerAssignment(flp);
nodep->replaceWith(trigAssignp);
trigAssignp->addNextHere(nbaEventControlp);
nbaEventControlp->addStmtsp(nodep);
insertBeforep = forkp;
if (!controlp) controlp = nbaEventControlp;
}
controlp->replaceWith(forkp);
forkp->addStmtsp(controlp);
}
UASSERT_OBJ(nodep, controlp, "Assignment should have timing control");
addCLocalScope(flp, insertBeforep);
// Function for replacing values with intermediate variables
const auto replaceWithIntermediate = [&](AstNodeExpr* const valuep,
const std::string& name) {
AstVarScope* const newvscp = createTemp(flp, name, valuep->dtypep(), insertBeforep);
valuep->replaceWith(new AstVarRef{flp, newvscp, VAccess::READ});
controlp->addHereThisAsNext(
new AstAssign{flp, new AstVarRef{flp, newvscp, VAccess::WRITE}, valuep});
};
// Create the intermediate select vars. Note: because 'foreach' proceeds in
// pre-order, and we replace indices in selects with variables, we cannot
// reach another select under the index position. This is exactly what
// we want as only the top level selects are LValues. As an example,
// this transforms 'x[a[i]][b[j]] = y'
// into 't1 = a[i]; t0 = b[j]; x[t1][t0] = y'.
nodep->lhsp()->foreach([&](AstSel* selp) {
if (VN_IS(selp->lsbp(), Const)) return;
replaceWithIntermediate(selp->lsbp(), m_intraLsbNames.get(nodep));
// widthp should be const
});
nodep->lhsp()->foreach([&](AstNodeSel* selp) {
if (VN_IS(selp->bitp(), Const)) return;
replaceWithIntermediate(selp->bitp(), m_intraIndexNames.get(nodep));
});
// Replace the RHS with an intermediate value var
replaceWithIntermediate(nodep->rhsp(), m_intraValueNames.get(nodep));
}
void visit(AstAssignW* nodep) override {
AstDelay* const netDelayp = getLhsNetDelayRecurse(nodep->lhsp());
if (!netDelayp && !nodep->timingControlp()) return;
// This assignment will be converted to an always. In some cases this may generate an
// UNOPTFLAT, e.g.: assign #1 clk = ~clk. We create a temp var for the LHS of this
// assign, to disable the UNOPTFLAT warning for it.
// TODO: Find a way to do this without introducing this var. Perhaps make
// V3SchedAcyclic recognize awaits and prevent it from treating this kind of logic as
// cyclic
AstNodeExpr* const lhsp = nodep->lhsp()->unlinkFrBack();
std::string varname;
if (auto* const refp = VN_CAST(lhsp, VarRef)) {
varname = m_contAssignVarNames.get(refp->name());
} else {
varname = m_contAssignVarNames.get(lhsp);
}
auto* const tempvscp = m_scopep->createTemp(varname, lhsp->dtypep());
tempvscp->varp()->delayp(netDelayp);
FileLine* const flp = nodep->fileline();
flp->modifyWarnOff(V3ErrorCode::UNOPTFLAT, true);
tempvscp->fileline(flp);
tempvscp->varp()->fileline(flp);
// Remap the LHS to the new temp var
nodep->lhsp(new AstVarRef{flp, tempvscp, VAccess::WRITE});
// Convert it to an always; the new assign with intra delay will be handled by
// visit(AstNodeAssign*)
AstAlways* const alwaysp = nodep->convertToAlways();
visit(alwaysp);
// Put the LHS back in the AssignW; put the temp var on the RHS
nodep->lhsp(lhsp);
nodep->rhsp(new AstVarRef{flp, tempvscp, VAccess::READ});
// Put the AssignW right after the always. Different order can produce UNOPTFLAT on the LHS
// var
alwaysp->addNextHere(nodep);
}
void visit(AstWaitFork* nodep) override {
AstCExpr* const exprp = new AstCExpr{nodep->fileline(), "vlProcess->completedFork()", 1};
exprp->pure(false);
AstWait* const waitp = new AstWait{nodep->fileline(), exprp, nullptr};
nodep->replaceWith(waitp);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
}
void visit(AstWait* nodep) override {
// Wait on changed events related to the vars in the wait statement
FileLine* const flp = nodep->fileline();
AstNode* const stmtsp = nodep->stmtsp();
if (stmtsp) stmtsp->unlinkFrBackWithNext();
AstNodeExpr* const condp = V3Const::constifyEdit(nodep->condp()->unlinkFrBack());
auto* const constp = VN_CAST(condp, Const);
if (constp) {
if (constp->isZero()) {
// We have to await forever instead of simply returning in case we're deep in a
// callstack
AstCExpr* const foreverp = new AstCExpr{flp, "VlForever{}", 0, true};
foreverp->dtypeSetVoid(); // TODO: this is sloppy but harmless
AstCAwait* const awaitp = new AstCAwait{flp, foreverp};
awaitp->dtypeSetVoid();
nodep->replaceWith(awaitp->makeStmt());
if (stmtsp) VL_DO_DANGLING(stmtsp->deleteTree(), stmtsp);
VL_DO_DANGLING(condp->deleteTree(), condp);
} else {
nodep->v3fatalSrc("constant wait should have been removed in "
"TimingSuspendableVisitor::visit(AstWait)");
}
} else if (needDynamicTrigger(condp)) {
// No point in making a sentree, just use the expression as sensitivity
// Put the event control in an if so we only wait if the condition isn't met already
auto* const ifp = new AstIf{
flp, new AstLogNot{flp, condp},
new AstEventControl{flp,
new AstSenTree{flp, new AstSenItem{flp, VEdgeType::ET_TRUE,
condp->cloneTree(false)}},
nullptr}};
if (stmtsp) AstNode::addNext<AstNode, AstNode>(ifp, stmtsp);
nodep->replaceWith(ifp);
} else {
// We are using a global sentree, so we cannot use ET_TRUE, as that could lead to the
// active region never converging. Because of this, we need to use ET_CHANGED in a
// loop.
AstEventControl* const controlp = new AstEventControl{
flp,
new AstSenTree{
flp, new AstSenItem{flp, VEdgeType::ET_CHANGED, condp->cloneTree(false)}},
nullptr};
controlp->user2(true); // Commit immediately
AstWhile* const loopp = new AstWhile{flp, new AstLogNot{flp, condp}, controlp};
if (stmtsp) AstNode::addNext<AstNode, AstNode>(loopp, stmtsp);
nodep->replaceWith(loopp);
}
VL_DO_DANGLING(nodep->deleteTree(), nodep);
}
void visit(AstBegin* nodep) override {
VL_RESTORER(m_procp);
m_procp = nodep;
if (hasFlags(nodep, T_HAS_PROC)) nodep->setNeedProcess();
iterateChildren(nodep);
}
void visit(AstFork* nodep) override {
if (nodep->user1SetOnce()) return;
v3Global.setUsesTiming();
// Create a unique name for this fork
nodep->name("__Vfork_" + cvtToStr(++m_forkCnt));
unsigned idx = 0; // Index for naming begins
AstNode* stmtp = nodep->stmtsp();
// Put each statement in a begin
while (stmtp) {
if (!VN_IS(stmtp, Begin)) {
auto* const beginp = new AstBegin{stmtp->fileline(), "", nullptr};
if (hasFlags(stmtp, T_HAS_PROC)) addFlags(beginp, T_HAS_PROC);
stmtp->replaceWith(beginp);
beginp->addStmtsp(stmtp);
stmtp = beginp;
}
auto* const beginp = VN_AS(stmtp, Begin);
stmtp = beginp->nextp();
iterate(beginp);
// Even if we do not find any awaits, we cannot simply inline the process here, as new
// awaits could be added later.
// Name the begin (later the name will be used for a new function)
beginp->name(nodep->name() + "__" + cvtToStr(idx++));
}
if (!nodep->joinType().joinNone()) makeForkJoin(nodep);
}
//--------------------
void visit(AstVar*) override {} // Accelerate
void visit(AstNode* nodep) override { iterateChildren(nodep); }
public:
// CONSTRUCTORS
explicit TimingControlVisitor(AstNetlist* nodep)
: m_netlistp{nodep} {
iterate(nodep);
}
~TimingControlVisitor() override = default;
};
//######################################################################
// Timing class functions
void V3Timing::timingAll(AstNetlist* nodep) {
UINFO(2, __FUNCTION__ << ": " << endl);
TimingSuspendableVisitor susVisitor{nodep};
if (v3Global.usesTiming()) TimingControlVisitor{nodep};
V3Global::dumpCheckGlobalTree("timing", 0, dumpTreeLevel() >= 3);
}
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