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V3Simulate.h
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V3Simulate.h
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// -*- mode: C++; c-file-style: "cc-mode" -*-
//*************************************************************************
// DESCRIPTION: Verilator: Simulate code to determine output values/variables
//
// Code available from: https://verilator.org
//
//*************************************************************************
//
// Copyright 2003-2022 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
//
//*************************************************************************
//
// void example_usage() {
// SimulateVisitor simvis (false, false);
// simvis.clear();
// // Set all inputs to the constant
// for (deque<AstVarScope*>::iterator it = m_inVarps.begin(); it!=m_inVarps.end(); ++it) {
// simvis.newValue(invscp, #);
// }
// // Simulate
// simvis.main(nodep);
// // Read outputs
// for (deque<AstVarScope*>::iterator it = m_outVarps.begin(); it!=m_outVarps.end(); ++it) {
// AstConst* outconstp = simvis.fetchOutNumberNull(outvscp);
//
//*************************************************************************
#ifndef VERILATOR_V3SIMULATE_H_
#define VERILATOR_V3SIMULATE_H_
#include "config_build.h"
#include "verilatedos.h"
#include "V3Error.h"
#include "V3Ast.h"
#include "V3Width.h"
#include "V3Task.h"
#include <deque>
#include <sstream>
#include <vector>
//============================================================================
//######################################################################
// Simulate class functions
class SimStackNode final {
public:
// MEMBERS
AstFuncRef* const m_funcp;
V3TaskConnects* const m_tconnects;
// CONSTRUCTORS
SimStackNode(AstFuncRef* funcp, V3TaskConnects* tconnects)
: m_funcp{funcp}
, m_tconnects{tconnects} {}
~SimStackNode() = default;
};
class SimulateVisitor VL_NOT_FINAL : public VNVisitor {
// Simulate a node tree, returning value of variables
// Two major operating modes:
// Test the tree to see if it is conformant
// Given a set of input values, find the output values
// Both are done in this same visitor to reduce risk; if a visitor
// is missing, we will simply not apply the optimization, rather then bomb.
private:
// NODE STATE
// Cleared on each always/assignw
const VNUser1InUse m_inuser1;
const VNUser2InUse m_inuser2;
const VNUser3InUse m_inuser3;
// Checking:
// AstVar(Scope)::user1() -> VarUsage. Set true to indicate tracking as lvalue/rvalue
// Simulating:
// AstConst::user2() -> bool. This AstConst (allocated by this class) is in use
// AstVar(Scope)::user3() -> AstConst*. Input value of variable or node
// (and output for non-delayed assignments)
// AstVar(Scope)::user2() -> AstCont*. Output value of variable (delayed assignments)
enum VarUsage : uint8_t { VU_NONE = 0, VU_LV = 1, VU_RV = 2, VU_LVDLY = 4 };
// STATE
// Major mode
bool m_checkOnly; ///< Checking only (no simulation) mode
bool m_scoped; ///< Running with AstVarScopes instead of AstVars
bool m_params; ///< Doing parameter propagation
// Checking:
string m_whyNotOptimizable; ///< String explaining why not optimizable or nullptr to optimize
AstNode* m_whyNotNodep; ///< First node not optimizable
bool m_anyAssignDly; ///< True if found a delayed assignment
bool m_anyAssignComb; ///< True if found a non-delayed assignment
bool m_inDlyAssign; ///< Under delayed assignment
int m_instrCount; ///< Number of nodes
int m_dataCount; ///< Bytes of data
AstJumpGo* m_jumpp; ///< Jump label we're branching from
// Simulating:
std::unordered_map<const AstNodeDType*, std::deque<AstConst*>>
m_constps; ///< Lists of all AstConst* allocated per dtype
std::vector<SimStackNode*> m_callStack; ///< Call stack for verbose error messages
// Cleanup
// V3Numbers that represents strings are a bit special and the API for
// V3Number does not allow changing them.
std::vector<AstNode*> m_reclaimValuesp; // List of allocated string numbers
// Note level 8&9 include debugging each simulation value
VL_DEBUG_FUNC; // Declare debug()
// Potentially very slow, intended for debugging
string prettyNumber(const V3Number* nump, AstNodeDType* dtypep) {
if (AstRefDType* const refdtypep = VN_CAST(dtypep, RefDType)) { //
dtypep = refdtypep->skipRefp();
}
if (AstStructDType* const stp = VN_CAST(dtypep, StructDType)) {
if (stp->packed()) {
std::ostringstream out;
out << "'{";
for (AstMemberDType* itemp = stp->membersp(); itemp;
itemp = VN_AS(itemp->nextp(), MemberDType)) {
const int width = itemp->width();
const int lsb = itemp->lsb();
const int msb = lsb + width - 1;
V3Number fieldNum(nump, width);
fieldNum.opSel(*nump, msb, lsb);
out << itemp->name() << ": ";
if (AstNodeDType* const childTypep = itemp->subDTypep()) {
out << prettyNumber(&fieldNum, childTypep);
} else {
out << fieldNum;
}
if (itemp->nextp()) out << ", ";
}
out << "}";
return out.str();
}
} else if (const AstPackArrayDType* const arrayp = VN_CAST(dtypep, PackArrayDType)) {
if (AstNodeDType* const childTypep = arrayp->subDTypep()) {
std::ostringstream out;
out << "[";
const int arrayElements = arrayp->elementsConst();
for (int element = 0; element < arrayElements; ++element) {
const int width = childTypep->width();
const int lsb = width * element;
const int msb = lsb + width - 1;
V3Number fieldNum(nump, width);
fieldNum.opSel(*nump, msb, lsb);
const int arrayElem = arrayp->lo() + element;
out << arrayElem << " = " << prettyNumber(&fieldNum, childTypep);
if (element < arrayElements - 1) out << ", ";
}
out << "]";
return out.str();
}
}
return nump->ascii();
}
// Checking METHODS
public:
/// Call other-this function on all new *non-constant* var references
virtual void varRefCb(AstVarRef* nodep) {}
void clearOptimizable(AstNode* nodep /*null ok*/, const string& why) {
// Something bad found. optimizable() will return false,
// and fetchConst should not be called or it may assert.
if (!m_whyNotNodep) {
m_whyNotNodep = nodep;
if (debug() >= 5) {
UINFO(0, "Clear optimizable: " << why);
if (nodep) cout << ": " << nodep;
cout << endl;
}
m_whyNotOptimizable = why;
std::ostringstream stack;
for (auto it = m_callStack.rbegin(); it != m_callStack.rend(); ++it) {
AstFuncRef* const funcp = (*it)->m_funcp;
stack << "\n " << funcp->fileline() << "... Called from "
<< funcp->prettyName() << "() with parameters:";
V3TaskConnects* tconnects = (*it)->m_tconnects;
for (V3TaskConnects::iterator conIt = tconnects->begin();
conIt != tconnects->end(); ++conIt) {
AstVar* const portp = conIt->first;
AstNode* const pinp = conIt->second->exprp();
AstNodeDType* const dtypep = pinp->dtypep();
if (AstConst* const valp = fetchConstNull(pinp))
stack << "\n " << portp->prettyName() << " = "
<< prettyNumber(&valp->num(), dtypep);
}
}
m_whyNotOptimizable += stack.str();
}
}
bool optimizable() const { return m_whyNotNodep == nullptr; }
string whyNotMessage() const { return m_whyNotOptimizable; }
AstNode* whyNotNodep() const { return m_whyNotNodep; }
bool isAssignDly() const { return m_anyAssignDly; }
int instrCount() const { return m_instrCount; }
int dataCount() const { return m_dataCount; }
// Simulation METHODS
private:
AstConst* allocConst(AstNode* nodep) {
// Save time - kept a list of allocated but unused values
// It would be more efficient to do this by size, but the extra accounting
// slows things down more than we gain.
AstConst* constp;
// Grab free list corresponding to this dtype
std::deque<AstConst*>& freeList = m_constps[nodep->dtypep()];
bool allocNewConst = true;
if (!freeList.empty()) {
constp = freeList.front();
if (!constp->user2()) {
// Front of free list is free, reuse it (otherwise allocate new node)
allocNewConst = false; // No need to allocate
// Mark the AstConst node as used, and move it to the back of the free list. This
// ensures that when all AstConst instances within the list are used, then the
// front of the list will be marked as used, in which case the enclosing 'if' will
// fail and we fall back to allocation.
constp->user2(1);
freeList.pop_front();
freeList.push_back(constp);
// configure const
constp->num().nodep(nodep);
}
}
if (allocNewConst) {
// Need to allocate new constant
constp = new AstConst(nodep->fileline(), AstConst::DtypedValue(), nodep->dtypep(), 0);
// Mark as in use, add to free list for later reuse
constp->user2(1);
freeList.push_back(constp);
}
constp->num().isDouble(nodep->isDouble());
constp->num().isString(nodep->isString());
return constp;
}
public:
void newValue(AstNode* nodep, const AstNode* valuep) {
if (const AstConst* const constp = VN_CAST(valuep, Const)) {
newConst(nodep)->num().opAssign(constp->num());
} else if (fetchValueNull(nodep) != valuep) {
// const_cast, as clonep() is set on valuep, but nothing should care
setValue(nodep, newTrackedClone(const_cast<AstNode*>(valuep)));
}
}
void newOutValue(AstNode* nodep, const AstNode* valuep) {
if (const AstConst* const constp = VN_CAST(valuep, Const)) {
newOutConst(nodep)->num().opAssign(constp->num());
} else if (fetchOutValueNull(nodep) != valuep) {
// const_cast, as clonep() is set on valuep, but nothing should care
setOutValue(nodep, newTrackedClone(const_cast<AstNode*>(valuep)));
}
}
private:
AstNode* newTrackedClone(AstNode* nodep) {
AstNode* const newp = nodep->cloneTree(false);
m_reclaimValuesp.push_back(newp);
return newp;
}
AstConst* newConst(AstNode* nodep) {
// Set a constant value for this node
if (!VN_IS(nodep->user3p(), Const)) {
AstConst* const constp = allocConst(nodep);
setValue(nodep, constp);
return constp;
} else {
return fetchConst(nodep);
}
}
AstConst* newOutConst(AstNode* nodep) {
// Set a var-output constant value for this node
if (!VN_IS(nodep->user2p(), Const)) {
AstConst* const constp = allocConst(nodep);
setOutValue(nodep, constp);
return constp;
} else {
return fetchOutConst(nodep);
}
}
public:
AstNode* fetchValueNull(AstNode* nodep) { return nodep->user3p(); }
private:
AstNode* fetchOutValueNull(AstNode* nodep) { return nodep->user2p(); }
AstConst* fetchConstNull(AstNode* nodep) { return VN_CAST(fetchValueNull(nodep), Const); }
AstConst* fetchOutConstNull(AstNode* nodep) {
return VN_CAST(fetchOutValueNull(nodep), Const);
}
AstNode* fetchValue(AstNode* nodep) {
AstNode* const valuep = fetchValueNull(nodep);
UASSERT_OBJ(valuep, nodep, "No value found for node.");
// UINFO(9, " fetch val " << *valuep << " on " << nodep << endl);
return valuep;
}
AstConst* fetchConst(AstNode* nodep) {
AstConst* const constp = fetchConstNull(nodep);
UASSERT_OBJ(constp, nodep, "No value found for node.");
// UINFO(9, " fetch num " << *constp << " on " << nodep << endl);
return constp;
}
AstConst* fetchOutConst(AstNode* nodep) {
AstConst* const constp = fetchOutConstNull(nodep);
UASSERT_OBJ(constp, nodep, "No value found for node.");
return constp;
}
public:
V3Number* fetchNumberNull(AstNode* nodep) {
AstConst* const constp = fetchConstNull(nodep);
if (constp) return &constp->num();
return nullptr;
}
V3Number* fetchOutNumberNull(AstNode* nodep) {
AstConst* const constp = fetchOutConstNull(nodep);
if (constp) return &constp->num();
return nullptr;
}
private:
void setValue(AstNode* nodep, const AstNode* valuep) {
UASSERT_OBJ(valuep, nodep, "Simulate setting null value");
UINFO(9, " set val " << valuep->name() << " on " << nodep << endl);
nodep->user3p((void*)valuep);
}
void setOutValue(AstNode* nodep, const AstNode* valuep) {
UASSERT_OBJ(valuep, nodep, "Simulate setting null value");
UINFO(9, " set oval " << valuep->name() << " on " << nodep << endl);
nodep->user2p((void*)valuep);
}
void checkNodeInfo(AstNode* nodep) {
if (m_checkOnly) {
m_instrCount += nodep->instrCount();
m_dataCount += nodep->width();
}
if (!nodep->isPredictOptimizable()) {
// UINFO(9, " !predictopt " << nodep << endl);
clearOptimizable(nodep, "Isn't predictable");
}
}
void badNodeType(AstNode* nodep) {
// Call for default node types, or other node types we don't know how to handle
checkNodeInfo(nodep);
if (optimizable()) {
// Hmm, what is this then?
// In production code, we'll just not optimize. It should be fixed though.
clearOptimizable(nodep,
"Unknown node type, perhaps missing visitor in SimulateVisitor");
#ifdef VL_DEBUG
UINFO(0, "Unknown node type in SimulateVisitor: " << nodep->prettyTypeName() << endl);
#endif
}
}
AstNode* varOrScope(AstVarRef* nodep) const {
AstNode* vscp;
if (m_scoped) {
vscp = nodep->varScopep();
} else {
vscp = nodep->varp();
}
UASSERT_OBJ(vscp, nodep, "Not linked");
return vscp;
}
int unrollCount() {
return m_params ? v3Global.opt.unrollCount() * 16 : v3Global.opt.unrollCount();
}
bool jumpingOver(AstNode* nodep) {
// True to jump over this node - all visitors must call this up front
return (m_jumpp && m_jumpp->labelp() != nodep);
}
void assignOutValue(AstNodeAssign* nodep, AstNode* vscp, const AstNode* valuep) {
if (VN_IS(nodep, AssignDly)) {
// Don't do setValue, as value isn't yet visible to following statements
newOutValue(vscp, valuep);
} else {
newValue(vscp, valuep);
newOutValue(vscp, valuep);
}
}
// VISITORS
virtual void visit(AstAlways* nodep) override {
if (jumpingOver(nodep)) return;
checkNodeInfo(nodep);
iterateChildren(nodep);
}
virtual void visit(AstSenTree* nodep) override {
// Sensitivities aren't inputs per se; we'll keep our tree under the same sens.
}
virtual void visit(AstVarRef* nodep) override {
if (jumpingOver(nodep)) return;
if (!optimizable()) return; // Accelerate
UASSERT_OBJ(nodep->varp(), nodep, "Unlinked");
iterateChildren(nodep->varp());
AstNode* const vscp = varOrScope(nodep);
// We can't have non-delayed assignments with same value on LHS and RHS
// as we don't figure out variable ordering.
// Delayed is OK though, as we'll decode the next state separately.
if (!VN_IS(nodep->varp()->dtypeSkipRefp(), BasicDType)
&& !VN_IS(nodep->varp()->dtypeSkipRefp(), PackArrayDType)
&& !VN_IS(nodep->varp()->dtypeSkipRefp(), UnpackArrayDType)
&& !VN_IS(nodep->varp()->dtypeSkipRefp(), StructDType))
clearOptimizable(nodep, "Array references/not basic");
if (nodep->access().isWriteOrRW()) {
if (m_inDlyAssign) {
if (!(vscp->user1() & VU_LVDLY)) {
vscp->user1(vscp->user1() | VU_LVDLY);
if (m_checkOnly) varRefCb(nodep);
}
} else { // nondly asn
if (!(vscp->user1() & VU_LV)) {
if (!m_params && (vscp->user1() & VU_RV)) {
clearOptimizable(nodep, "Var read & write");
}
vscp->user1(vscp->user1() | VU_LV);
if (m_checkOnly) varRefCb(nodep);
}
}
}
if (nodep->access().isReadOrRW()) {
if (!(vscp->user1() & VU_RV)) {
if (!m_params && (vscp->user1() & VU_LV)) {
clearOptimizable(nodep, "Var write & read");
}
vscp->user1(vscp->user1() | VU_RV);
const bool isConst = nodep->varp()->isParam() && nodep->varp()->valuep();
AstNode* const valuep
= isConst ? fetchValueNull(nodep->varp()->valuep()) : nullptr;
if (isConst
&& valuep) { // Propagate PARAM constants for constant function analysis
if (!m_checkOnly && optimizable()) newValue(vscp, valuep);
} else {
if (m_checkOnly) varRefCb(nodep);
}
}
}
if (!m_checkOnly && optimizable()) { // simulating
UASSERT_OBJ(nodep->access().isReadOnly(), nodep,
"LHS varref should be handled in AstAssign visitor.");
{
// Return simulation value - copy by reference instead of value for speed
AstNode* valuep = fetchValueNull(vscp);
if (!valuep) {
if (m_params) {
clearOptimizable(
nodep, "Language violation: reference to non-function-local variable");
} else {
nodep->v3fatalSrc(
"Variable value should have been set before any visitor called.");
}
valuep = allocConst(nodep); // Any value; just so recover from error
}
setValue(nodep, valuep);
}
}
}
virtual void visit(AstVarXRef* nodep) override {
if (jumpingOver(nodep)) return;
if (m_scoped) {
badNodeType(nodep);
return;
} else {
clearOptimizable(nodep, "Language violation: Dotted hierarchical references not "
"allowed in constant functions");
}
}
virtual void visit(AstNodeFTask* nodep) override {
if (jumpingOver(nodep)) return;
if (!m_params) {
badNodeType(nodep);
return;
}
if (nodep->dpiImport()) {
if (m_params) {
nodep->v3error("Constant function may not be DPI import (IEEE 1800-2017 13.4.3)");
}
clearOptimizable(nodep, "DPI import functions aren't simulatable");
}
if (nodep->underGenerate()) {
nodep->v3error(
"Constant function may not be declared under generate (IEEE 1800-2017 13.4.3)");
clearOptimizable(nodep, "Constant function called under generate");
}
checkNodeInfo(nodep);
iterateChildren(nodep);
}
virtual void visit(AstNodeIf* nodep) override {
if (jumpingOver(nodep)) return;
UINFO(5, " IF " << nodep << endl);
checkNodeInfo(nodep);
if (m_checkOnly) {
iterateChildren(nodep);
} else {
iterateAndNextNull(nodep->condp());
if (optimizable()) {
if (fetchConst(nodep->condp())->num().isNeqZero()) {
iterateAndNextNull(nodep->ifsp());
} else {
iterateAndNextNull(nodep->elsesp());
}
}
}
}
virtual void visit(AstConst* nodep) override {
checkNodeInfo(nodep);
if (!m_checkOnly && optimizable()) newValue(nodep, nodep);
}
virtual void visit(AstInitArray* nodep) override {
checkNodeInfo(nodep);
if (!m_checkOnly && optimizable()) newValue(nodep, nodep);
}
virtual void visit(AstEnumItemRef* nodep) override {
checkNodeInfo(nodep);
UASSERT_OBJ(nodep->itemp(), nodep, "Not linked");
if (!m_checkOnly && optimizable()) {
AstNode* const valuep = nodep->itemp()->valuep();
if (valuep) {
iterateAndNextNull(valuep);
if (optimizable()) newValue(nodep, fetchValue(valuep));
} else {
clearOptimizable(nodep, "No value found for enum item"); // LCOV_EXCL_LINE
}
}
}
virtual void visit(AstNodeUniop* nodep) override {
if (!optimizable()) return; // Accelerate
checkNodeInfo(nodep);
iterateChildren(nodep);
if (!m_checkOnly && optimizable()) {
nodep->numberOperate(newConst(nodep)->num(), fetchConst(nodep->lhsp())->num());
}
}
virtual void visit(AstNodeBiop* nodep) override {
if (!optimizable()) return; // Accelerate
checkNodeInfo(nodep);
iterateChildren(nodep);
if (!m_checkOnly && optimizable()) {
nodep->numberOperate(newConst(nodep)->num(), fetchConst(nodep->lhsp())->num(),
fetchConst(nodep->rhsp())->num());
}
}
virtual void visit(AstNodeTriop* nodep) override {
if (!optimizable()) return; // Accelerate
checkNodeInfo(nodep);
iterateChildren(nodep);
if (!m_checkOnly && optimizable()) {
nodep->numberOperate(newConst(nodep)->num(), fetchConst(nodep->lhsp())->num(),
fetchConst(nodep->rhsp())->num(),
fetchConst(nodep->thsp())->num());
}
}
virtual void visit(AstNodeQuadop* nodep) override {
if (!optimizable()) return; // Accelerate
checkNodeInfo(nodep);
iterateChildren(nodep);
if (!m_checkOnly && optimizable()) {
nodep->numberOperate(newConst(nodep)->num(), fetchConst(nodep->lhsp())->num(),
fetchConst(nodep->rhsp())->num(),
fetchConst(nodep->thsp())->num(),
fetchConst(nodep->fhsp())->num());
}
}
virtual void visit(AstLogAnd* nodep) override {
// Need to short circuit
if (!optimizable()) return; // Accelerate
checkNodeInfo(nodep);
if (m_checkOnly) {
iterateChildren(nodep);
} else {
iterate(nodep->lhsp());
if (optimizable()) {
if (fetchConst(nodep->lhsp())->num().isNeqZero()) {
iterate(nodep->rhsp());
newValue(nodep, fetchValue(nodep->rhsp()));
} else {
newValue(nodep, fetchValue(nodep->lhsp())); // a zero
}
}
}
}
virtual void visit(AstLogOr* nodep) override {
// Need to short circuit
if (!optimizable()) return; // Accelerate
checkNodeInfo(nodep);
if (m_checkOnly) {
iterateChildren(nodep);
} else {
iterate(nodep->lhsp());
if (optimizable()) {
if (fetchConst(nodep->lhsp())->num().isNeqZero()) {
newValue(nodep, fetchValue(nodep->lhsp())); // a one
} else {
iterate(nodep->rhsp());
newValue(nodep, fetchValue(nodep->rhsp()));
}
}
}
}
virtual void visit(AstLogIf* nodep) override {
// Need to short circuit, same as (!A || B)
if (!optimizable()) return; // Accelerate
checkNodeInfo(nodep);
if (m_checkOnly) {
iterateChildren(nodep);
} else {
iterate(nodep->lhsp());
if (optimizable()) {
if (fetchConst(nodep->lhsp())->num().isEqZero()) {
const AstConst cnst(nodep->fileline(), AstConst::WidthedValue(), 1,
1); // a one
newValue(nodep, &cnst); // a one
} else {
iterate(nodep->rhsp());
newValue(nodep, fetchValue(nodep->rhsp()));
}
}
}
}
virtual void visit(AstNodeCond* nodep) override {
// We could use above visit(AstNodeTriop), but need to do short circuiting.
// It's also slower even O(n^2) to evaluate both sides when we
// really only need to evaluate one side.
if (!optimizable()) return; // Accelerate
checkNodeInfo(nodep);
if (m_checkOnly) {
iterateChildren(nodep);
} else {
iterate(nodep->condp());
if (optimizable()) {
if (fetchConst(nodep->condp())->num().isNeqZero()) {
iterate(nodep->expr1p());
newValue(nodep, fetchValue(nodep->expr1p()));
} else {
iterate(nodep->expr2p());
newValue(nodep, fetchValue(nodep->expr2p()));
}
}
}
}
void handleAssignArray(AstNodeAssign* nodep, AstArraySel* selp) {
iterateAndNextNull(nodep->rhsp()); // Value to assign
// At present we only handle single dimensional assignments
// To do better, we need the concept of lvalues, or similar, to know where/how to insert
checkNodeInfo(selp);
iterateAndNextNull(selp->bitp()); // Bit index
AstVarRef* const varrefp = VN_CAST(selp->fromp(), VarRef);
if (!varrefp) {
clearOptimizable(nodep, "Array select LHS isn't simple variable");
return;
}
AstUnpackArrayDType* const arrayp
= VN_AS(varrefp->varp()->dtypeSkipRefp(), UnpackArrayDType);
UASSERT_OBJ(arrayp, nodep, "Array select of non-array dtype");
AstBasicDType* const basicp = VN_CAST(arrayp->subDTypep()->skipRefp(), BasicDType);
if (!basicp) {
clearOptimizable(nodep, "Array of non-basic dtype (e.g. array-of-array)");
return;
}
if (!m_checkOnly && optimizable()) {
AstNode* const vscp = varOrScope(varrefp);
AstInitArray* initp = nullptr;
if (AstInitArray* const vscpnump = VN_CAST(fetchOutValueNull(vscp), InitArray)) {
initp = vscpnump;
} else if (AstInitArray* const vscpnump = VN_CAST(fetchValueNull(vscp), InitArray)) {
initp = vscpnump;
} else { // Assignment to unassigned variable, all bits are X
// TODO generic initialization which builds X/arrays by recursion
AstConst* const outconstp = new AstConst(
nodep->fileline(), AstConst::WidthedValue(), basicp->widthMin(), 0);
if (basicp->isZeroInit()) {
outconstp->num().setAllBits0();
} else {
outconstp->num().setAllBitsX();
}
initp = new AstInitArray(nodep->fileline(), arrayp, outconstp);
m_reclaimValuesp.push_back(initp);
}
const uint32_t index = fetchConst(selp->bitp())->toUInt();
AstNode* const valuep = newTrackedClone(fetchValue(nodep->rhsp()));
UINFO(9, " set val[" << index << "] = " << valuep << endl);
// Values are in the "real" tree under the InitArray so can eventually extract it,
// Not in the usual setValue (pointed to by user2/3p)
initp->addIndexValuep(index, valuep);
if (debug() >= 9) initp->dumpTree(cout, "-array-");
assignOutValue(nodep, vscp, initp);
}
}
void handleAssignSel(AstNodeAssign* nodep, AstSel* selp) {
AstVarRef* varrefp = nullptr;
V3Number lsb(nodep);
iterateAndNextNull(nodep->rhsp()); // Value to assign
handleAssignSelRecurse(nodep, selp, varrefp /*ref*/, lsb /*ref*/, 0);
if (!m_checkOnly && optimizable()) {
UASSERT_OBJ(varrefp, nodep,
"Indicated optimizable, but no variable found on RHS of select");
AstNode* const vscp = varOrScope(varrefp);
AstConst* outconstp = nullptr;
if (AstConst* const vscpnump = fetchOutConstNull(vscp)) {
outconstp = vscpnump;
} else if (AstConst* const vscpnump = fetchConstNull(vscp)) {
outconstp = vscpnump;
} else { // Assignment to unassigned variable, all bits are X or 0
outconstp = new AstConst(nodep->fileline(), AstConst::WidthedValue(),
varrefp->varp()->widthMin(), 0);
if (varrefp->varp()->basicp() && varrefp->varp()->basicp()->isZeroInit()) {
outconstp->num().setAllBits0();
} else {
outconstp->num().setAllBitsX();
}
}
outconstp->num().opSelInto(fetchConst(nodep->rhsp())->num(), lsb, selp->widthConst());
assignOutValue(nodep, vscp, outconstp);
}
}
void handleAssignSelRecurse(AstNodeAssign* nodep, AstSel* selp, AstVarRef*& outVarrefpRef,
V3Number& lsbRef, int depth) {
// Recurse down to find final variable being set (outVarrefp), with
// lsb to be eventually set on lsbRef
checkNodeInfo(selp);
iterateAndNextNull(selp->lsbp()); // Bit index
if (AstVarRef* const varrefp = VN_CAST(selp->fromp(), VarRef)) {
outVarrefpRef = varrefp;
lsbRef = fetchConst(selp->lsbp())->num();
return; // And presumably still optimizable()
} else if (AstSel* const subselp = VN_CAST(selp->lhsp(), Sel)) {
V3Number sublsb(nodep);
handleAssignSelRecurse(nodep, subselp, outVarrefpRef, sublsb /*ref*/, depth + 1);
if (optimizable()) {
lsbRef = sublsb;
lsbRef.opAdd(sublsb, fetchConst(selp->lsbp())->num());
}
} else {
clearOptimizable(nodep, "Select LHS isn't simple variable");
}
}
virtual void visit(AstNodeAssign* nodep) override {
if (jumpingOver(nodep)) return;
if (!optimizable()) return; // Accelerate
if (VN_IS(nodep, AssignForce)) {
clearOptimizable(nodep, "Force");
} else if (VN_IS(nodep, AssignDly)) {
if (m_anyAssignComb) clearOptimizable(nodep, "Mix of dly/non-dly assigns");
m_anyAssignDly = true;
m_inDlyAssign = true;
} else {
if (m_anyAssignDly) clearOptimizable(nodep, "Mix of dly/non-dly assigns");
m_anyAssignComb = true;
}
if (AstSel* const selp = VN_CAST(nodep->lhsp(), Sel)) {
if (!m_params) {
clearOptimizable(nodep, "LHS has select");
return;
}
handleAssignSel(nodep, selp);
} else if (AstArraySel* const selp = VN_CAST(nodep->lhsp(), ArraySel)) {
if (!m_params) {
clearOptimizable(nodep, "LHS has select");
return;
}
handleAssignArray(nodep, selp);
} else if (!VN_IS(nodep->lhsp(), VarRef)) {
clearOptimizable(nodep, "LHS isn't simple variable");
} else if (m_checkOnly) {
iterateChildren(nodep);
} else if (optimizable()) {
iterateAndNextNull(nodep->rhsp());
if (optimizable()) {
AstNode* const vscp = varOrScope(VN_CAST(nodep->lhsp(), VarRef));
assignOutValue(nodep, vscp, fetchValue(nodep->rhsp()));
}
}
m_inDlyAssign = false;
}
virtual void visit(AstArraySel* nodep) override {
checkNodeInfo(nodep);
iterateChildren(nodep);
if (AstInitArray* const initp = VN_CAST(fetchValueNull(nodep->fromp()), InitArray)) {
AstConst* const indexp = fetchConst(nodep->bitp());
const uint32_t offset = indexp->num().toUInt();
AstNode* const itemp = initp->getIndexDefaultedValuep(offset);
if (!itemp) {
clearOptimizable(nodep, "Array initialization has too few elements, need element "
+ cvtToStr(offset));
} else {
setValue(nodep, itemp);
}
} else {
clearOptimizable(nodep, "Array select of non-array");
}
}
virtual void visit(AstBegin* nodep) override {
checkNodeInfo(nodep);
iterateChildren(nodep);
}
virtual void visit(AstNodeCase* nodep) override {
if (jumpingOver(nodep)) return;
UINFO(5, " CASE " << nodep << endl);
checkNodeInfo(nodep);
if (m_checkOnly) {
iterateChildren(nodep);
} else if (optimizable()) {
iterateAndNextNull(nodep->exprp());
bool hit = false;
for (AstCaseItem* itemp = nodep->itemsp(); itemp;
itemp = VN_AS(itemp->nextp(), CaseItem)) {
if (!itemp->isDefault()) {
for (AstNode* ep = itemp->condsp(); ep; ep = ep->nextp()) {
if (hit) break;
iterateAndNextNull(ep);
if (optimizable()) {
V3Number match(nodep, 1);
match.opEq(fetchConst(nodep->exprp())->num(), fetchConst(ep)->num());
if (match.isNeqZero()) {
iterateAndNextNull(itemp->bodysp());
hit = true;
}
}
}
}
}
// Else default match
for (AstCaseItem* itemp = nodep->itemsp(); itemp;
itemp = VN_AS(itemp->nextp(), CaseItem)) {
if (hit) break;
if (!hit && itemp->isDefault()) {
iterateAndNextNull(itemp->bodysp());
hit = true;
}
}
}
}
virtual void visit(AstCaseItem* nodep) override {
// Real handling is in AstNodeCase
if (jumpingOver(nodep)) return;
checkNodeInfo(nodep);
iterateChildren(nodep);
}
virtual void visit(AstComment*) override {}
virtual void visit(AstJumpBlock* nodep) override {
if (jumpingOver(nodep)) return;
iterateChildren(nodep);
}
virtual void visit(AstJumpGo* nodep) override {
if (jumpingOver(nodep)) return;
checkNodeInfo(nodep);
if (!m_checkOnly) {
UINFO(5, " JUMP GO " << nodep << endl);
m_jumpp = nodep;
}
}
virtual void visit(AstJumpLabel* nodep) override {
// This only supports forward jumps. That's all we make at present,
// AstJumpGo::broken uses brokeExistsBelow() to check this.
if (jumpingOver(nodep)) return;
checkNodeInfo(nodep);
iterateChildren(nodep);
if (m_jumpp && m_jumpp->labelp() == nodep) {
UINFO(5, " JUMP DONE " << nodep << endl);
m_jumpp = nullptr;
}
}
virtual void visit(AstStop* nodep) override {
if (jumpingOver(nodep)) return;
if (m_params) { // This message seems better than an obscure $stop
// The spec says $stop is just ignored, it seems evil to ignore assertions
clearOptimizable(
nodep,
"$stop executed during function constification; maybe indicates assertion firing");
}
checkNodeInfo(nodep);
}
virtual void visit(AstNodeFor* nodep) override {
// Doing lots of Whiles is slow, so only for parameters
UINFO(5, " FOR " << nodep << endl);
if (!m_params) {
badNodeType(nodep);
return;
}
checkNodeInfo(nodep);
if (m_checkOnly) {
iterateChildren(nodep);
} else if (optimizable()) {
int loops = 0;
iterateAndNextNull(nodep->initsp());
while (true) {
UINFO(5, " FOR-ITER " << nodep << endl);
iterateAndNextNull(nodep->condp());
if (!optimizable()) break;
if (!fetchConst(nodep->condp())->num().isNeqZero()) { //
break;
}
iterateAndNextNull(nodep->bodysp());
iterateAndNextNull(nodep->incsp());
if (loops++ > unrollCount() * 16) {
clearOptimizable(nodep, "Loop unrolling took too long; probably this is an"
"infinite loop, or set --unroll-count above "
+ cvtToStr(unrollCount()));
break;
}
}
}
}
virtual void visit(AstWhile* nodep) override {
// Doing lots of Whiles is slow, so only for parameters
if (jumpingOver(nodep)) return;
UINFO(5, " WHILE " << nodep << endl);
if (!m_params) {
badNodeType(nodep);
return;
}
checkNodeInfo(nodep);
if (m_checkOnly) {
iterateChildren(nodep);
} else if (optimizable()) {
int loops = 0;
while (true) {
UINFO(5, " WHILE-ITER " << nodep << endl);
iterateAndNextNull(nodep->precondsp());
if (jumpingOver(nodep)) break;
iterateAndNextNull(nodep->condp());
if (jumpingOver(nodep)) break;
if (!optimizable()) break;
if (!fetchConst(nodep->condp())->num().isNeqZero()) { //
break;
}
iterateAndNextNull(nodep->bodysp());
if (jumpingOver(nodep)) break;
iterateAndNextNull(nodep->incsp());
if (jumpingOver(nodep)) break;
// Prep for next loop
if (loops++ > unrollCount() * 16) {
clearOptimizable(nodep,
"Loop unrolling took too long; probably this is an infinite"
" loop, or set --unroll-count above "
+ cvtToStr(unrollCount()));
break;
}
}
}
}
virtual void visit(AstFuncRef* nodep) override {
if (jumpingOver(nodep)) return;
if (!optimizable()) return; // Accelerate
UINFO(5, " FUNCREF " << nodep << endl);
if (!m_params) {
badNodeType(nodep);
return;
}
AstNodeFTask* funcp = nodep->taskp();
UASSERT_OBJ(funcp, nodep, "Not linked");
if (m_params) V3Width::widthParamsEdit(funcp);
VL_DANGLING(funcp); // Make sure we've sized the function
funcp = nodep->taskp();
UASSERT_OBJ(funcp, nodep, "Not linked");
if (funcp->recursive()) {
// Because we attach values to nodes rather then making a stack, this is a mess
// When we do support this, we need a stack depth limit of 1K or something,
// and the t_func_recurse_param_bad.v test should check that limit's error message
clearOptimizable(funcp, "Unsupported: Recursive constant functions");
return;
}
// Apply function call values to function
V3TaskConnects tconnects = V3Task::taskConnects(nodep, nodep->taskp()->stmtsp());
// Must do this in two steps, eval all params, then apply them
// Otherwise chained functions may have the wrong results
for (V3TaskConnects::iterator it = tconnects.begin(); it != tconnects.end(); ++it) {
AstVar* const portp = it->first;
AstNode* const pinp = it->second->exprp();
if (pinp) { // Else too few arguments in function call - ignore it
if (portp->isWritable()) {
clearOptimizable(
portp,
"Language violation: Outputs/refs not allowed in constant functions");
return;
}