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verilator/src/V3SplitVar.cpp

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// -*- mode: C++; c-file-style: "cc-mode" -*-
//*************************************************************************
// DESCRIPTION: Verilator: Break variables into separate words to avoid UNOPTFLAT
//
// Code available from: https://verilator.org
//
//*************************************************************************
//
// Copyright 2003-2020 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.
//
// Verilator is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
//*************************************************************************
// V3SplitVar divides a variable into multiple variables to avoid UNOPTFLAT warning
// and get better perfomance.
// Variables to be split must be marked by /*verilator split_var*/ pragma.
// There are sveral kinds of data types that may cause the warning.
// 1) Unpacked arrays
// 2) Packed arrays
// 3) Unpacked structs
// 4) Packed structs
// 5) Bitfields within a signal. (Especially Verilog code predating structs/2D arrays.)
// 2-5 above are treated as bitfields in verilator.
//
// What this pass does looks as below.
//
// logic [1:0] unpcked_array_var[0:1]; /*verilator split_var*/
// always_comb begin
// unpacked_array_var[1] = unpacked_array_var[0]; // UNOPTFLAT warning
// end
// logic [3:0] packed_var; /*verilator split_var*/
// always_comb begin
// if (some_cond) begin
// packed_var = 4'b0;
// end else begin
// packed_var[3] = some_input0;
// packed_var[2:0] = some_input1;
// end
// end
//
// is converted to
//
// logic [1:0] unpcked_array_var0;
// logic [1:0] unpcked_array_var1;
// always_comb begin
// unpacked_array_var1 = unpacked_array_var0;
// end
// logic packed_var__BRA__3__KET__;
// logic [2:0] packed_var__BRA__2_0__KET__;
// always_comb begin
// if (some_cond) begin
// {packed_var__BRA__3__KET__, packed_var__BRA__2_0__KET__} = 4'b0;
// end else begin
// packed_var__BRA__3__KET__ = some_input0;
// packed_var__BRA__2_0__KET__ = some_input1;
// end
// end
// </pre>
//
//
//*************************************************************************
#include "config_build.h"
#include "verilatedos.h"
#include "V3Ast.h"
#include "V3Const.h"
#include "V3Global.h"
#include "V3SplitVar.h"
#include "V3Stats.h"
#include <algorithm> // sort
#include <vector>
#include VL_INCLUDE_UNORDERED_MAP
#include VL_INCLUDE_UNORDERED_SET
//######################################################################
// Find a variable with pragma
// the following code
// logic [7:0] var0 = 8'b0; /* verilator split_var*/
// generates AST like:
//
// 1:2: VAR var0 VAR
// 1:2: INITIAL
// 1:2:1: ASSIGN
// 1:2:1:1: CONST
// 1:2:1:2: VARREF var0 [LV]
// 1:2: PRAGMA <= PRAGMA comes after the initial VARREF
//
// To catch all VARREF, 2-pass scan is used.
// 1st scan:Just collect VAR and PRAGMA
// 2nd scan:Actual splitting
class ScanPragmaVisitor : public AstNVisitor {
AstVar* m_lastVarp; // the most recently declared variable
std::vector<std::pair<AstPragma*, AstVar*> > m_vars;
virtual void visit(AstNode* nodep) VL_OVERRIDE { iterateChildren(nodep); }
virtual void visit(AstModule* nodep) VL_OVERRIDE {
UASSERT_OBJ(nodep == NULL, nodep, "This class must be used within a module");
}
virtual void visit(AstVar* nodep) VL_OVERRIDE { m_lastVarp = nodep; }
virtual void visit(AstPragma* pragmap) VL_OVERRIDE {
if (pragmap->pragType() != AstPragmaType::SPLIT_VAR) return; // nothing to do
// when m_lastVarp == NULL, the pragma is stray pragma.
m_vars.push_back(std::make_pair(pragmap, m_lastVarp));
m_lastVarp = NULL;
}
ScanPragmaVisitor()
: m_lastVarp(NULL) {}
public:
static std::vector<std::pair<AstPragma*, AstVar*> > scan(AstNodeModule* modp) {
ScanPragmaVisitor v;
v.iterateChildren(modp);
return v.m_vars;
}
};
//######################################################################
// Split Unpacked Variables
class SplitUnpackedVarVisitor : public AstNVisitor {
AstNodeModule* m_modp; // current module
int m_numSplit; // total number of split variable
bool m_firstRun; // true for the first pass
// key:variable to be split. value:location where the variable is referenced.
vl_unordered_map<AstVar*, std::vector<AstArraySel*> > m_refs;
// This visitor is used before V3Const::constifyAllLint(),
// some parameters need to be resolved here, but don't abuse this function.
static AstConst* constifyIfNot(AstNode* nodep) {
AstConst* constp = VN_CAST(nodep, Const);
if (!constp) {
UINFO(4, nodep << " is expected to be constant, but not\n");
AstNode* constified = V3Const::constifyEdit(nodep);
UINFO(4, "After constified:" << constified << '\n');
constp = VN_CAST(constified, Const);
}
return constp;
}
static int outerMostSizeOfUnpackedArray(AstVar* nodep) {
AstUnpackArrayDType* dtypep = VN_CAST(nodep->dtypep(), UnpackArrayDType);
UASSERT_OBJ(dtypep, nodep, "Must be unapcked array");
return dtypep->msb() - dtypep->lsb() + 1;
}
virtual void visit(AstNode* nodep) VL_OVERRIDE { iterateChildren(nodep); }
virtual void visit(AstNodeModule* nodep) VL_OVERRIDE {
UASSERT_OBJ(m_modp == NULL, m_modp, "Nested module declration");
m_modp = nodep;
std::vector<std::pair<AstPragma*, AstVar*> > vars = ScanPragmaVisitor::scan(nodep);
for (size_t i = 0; i < vars.size(); ++i) {
AstPragma* pragmap = vars[i].first;
AstVar* varp = vars[i].second;
if (pragmap->pragType() != AstPragmaType::SPLIT_VAR) continue; // nothing to do
bool keepPragma = false;
if (!varp) {
pragmap->v3warn(SPLITVAR, "Unexpected location for split_var pragma.");
} else if (!canSplit(varp)) {
// maybe packed variable which will be split later.
keepPragma = true; // SplitPackedVarVisitor will read this pragma again later.
} else { // finally find a good candidate
UINFO(4, varp->name() << " is added to candidate list.\n");
m_refs.insert(std::make_pair(varp, std::vector<AstArraySel*>()));
}
if (!keepPragma) {
pragmap->unlinkFrBack()->deleteTree(); VL_DANGLING(vars[i].first);
}
}
iterateChildren(nodep);
split();
m_modp = NULL;
}
virtual void visit(AstVarRef* nodep) VL_OVERRIDE {
AstVar* varp = nodep->varp();
if (m_refs.find(varp) == m_refs.end()) return; // variable without split_var pragma
if (m_firstRun)
nodep->v3warn(
SPLITVAR,
"Variable " << varp->prettyNameQ()
<< " will not be split because the entire unpacked array is referred."
" Such access is not supported yet.\n");
m_refs.erase(varp);
}
static void splitSimpleAssign(AstNodeAssign* asnp, AstVarRef* lhsp, AstVarRef* rhsp,
int lstart, int rstart, int num) {
for (int i = 0; i < num; ++i) {
AstVarRef* lrefp = new AstVarRef(lhsp->fileline(), lhsp->varp(), true);
AstVarRef* rrefp = new AstVarRef(rhsp->fileline(), rhsp->varp(), false);
AstArraySel* lselp = new AstArraySel(lhsp->fileline(), lrefp, lstart + i);
AstArraySel* rselp = new AstArraySel(rhsp->fileline(), rrefp, rstart + i);
// the added new assignment statement will be visited later.
asnp->addNext(asnp->cloneType(lselp, rselp));
}
}
// Unroll assignments of SliceSel or entire unpacked array to multiple assignment
virtual void visit(AstNodeAssign* nodep) VL_OVERRIDE {
AstSliceSel* lsel = VN_CAST(nodep->lhsp(), SliceSel);
AstSliceSel* rsel = VN_CAST(nodep->rhsp(), SliceSel);
AstVarRef* lhsp = VN_CAST(lsel ? lsel->fromp() : nodep->lhsp(), VarRef);
AstVarRef* rhsp = VN_CAST(rsel ? rsel->fromp() : nodep->rhsp(), VarRef);
// unless simple assignment, nothing to do in this function
if (!lhsp || !rhsp) {
iterateChildren(nodep);
return;
}
// if nodep is a simple assignment of variables without split_var pragma, quick exit
if (m_refs.find(lhsp->varp()) == m_refs.end() && m_refs.find(rhsp->varp()) == m_refs.end())
return;
int lstart, lnum, rstart, rnum;
if (lsel) {
lstart = lsel->declRange().lo();
lnum = lsel->declRange().elements();
} else { // LHS is entire array
lstart = 0;
lnum = outerMostSizeOfUnpackedArray(lhsp->varp());
}
if (rsel) {
rstart = rsel->declRange().lo();
rnum = rsel->declRange().elements();
} else { // RHS is entire array
rstart = 0;
rnum = outerMostSizeOfUnpackedArray(rhsp->varp());
}
if (lnum != rnum) return; // strange. V3Slice will show proper diagnosis
splitSimpleAssign(nodep, lhsp, rhsp, lstart, rstart, lnum);
nodep->unlinkFrBack()->deleteTree(); VL_DANGLING(nodep);
}
virtual void visit(AstArraySel* nodep) VL_OVERRIDE {
AstVarRef* vrefp = VN_CAST(nodep->fromp(), VarRef);
if (!vrefp) {
iterateChildren(nodep);
return;
}
AstVar* varp = vrefp->varp();
if (m_refs.find(varp) == m_refs.end()) return; // variable without split_var pragma
AstConst* indexp = constifyIfNot(nodep->bitp());
if (indexp) { // OK
m_refs[varp].push_back(nodep);
} else {
if (m_firstRun)
nodep->bitp()->v3warn(
SPLITVAR,
"Variable "
<< vrefp->prettyNameQ()
<< " will not be split because index cannot be determined statically.");
m_refs.erase(varp);
}
}
// The actual splitting operation is done in this function.
void split() {
for (vl_unordered_map<AstVar*, std::vector<AstArraySel*> >::iterator it = m_refs.begin(),
it_end = m_refs.end();
it != it_end; ++it) {
UINFO(3, "In module " << m_modp->name() << " var " << it->first->prettyNameQ()
<< " which has " << it->second.size()
<< " refs will be split.\n");
AstVar* varp = it->first;
AstNode* insertp = varp;
AstUnpackArrayDType* dtypep = VN_CAST(varp->dtypep(), UnpackArrayDType);
std::vector<AstVar*> vars;
// Add the split variables
for (vlsint32_t i = 0; i <= dtypep->msb() - dtypep->lsb(); ++i) {
// const std::string name = varp->name() + "__BRA__" + AstNode::encodeNumber(i + dtypep->lsb()) + "__KET__";
// unpacked array is traced as var(idx).
const std::string name = varp->name() + AstNode::encodeName('(' + cvtToStr(i + dtypep->lsb()) + ')');
AstVar* newp = new AstVar(varp->fileline(), varp->varType(), name, dtypep->subDTypep());
newp->trace(varp->isTrace());
insertp->addNextHere(newp);
if (newp->width() == 1) { // no need to try splitting
insertp = newp;
} else {
newp->addNextHere(insertp = new AstPragma(varp->fileline(), AstPragmaType::SPLIT_VAR));
}
vars.push_back(newp);
}
// refer the split variable
for (size_t i = 0; i < it->second.size(); ++i) {
AstArraySel* selp = it->second[i];
AstVarRef* vrefp = VN_CAST(selp->fromp(), VarRef);
AstConst* indexp = VN_CAST(selp->bitp(), Const);
UASSERT_OBJ(vrefp && indexp, selp, "already checked");
const uint32_t idx = indexp->toUInt();
// V3Width:width() removes VAR_BASE attribute and make index 0-origin.
AstVarRef* new_vref = new AstVarRef(selp->fileline(), vars.at(idx), vrefp->lvalue());
selp->replaceWith(new_vref);
selp->deleteTree(); VL_DANGLING(selp);
}
varp->unlinkFrBack()->deleteTree(); VL_DANGLING(varp);
++m_numSplit;
}
m_refs.clear(); // done
}
public:
SplitUnpackedVarVisitor(AstNetlist* nodep, bool firstRun)
: m_modp(NULL)
, m_numSplit(0)
, m_firstRun(firstRun) {
iterate(nodep);
}
~SplitUnpackedVarVisitor() {
UASSERT(m_refs.empty(), "Don't forget to call split()");
if (m_firstRun) V3Stats::addStat("SplitVar, Split unpacked arrays", m_numSplit);
}
int numSplit() const { return m_numSplit; }
VL_DEBUG_FUNC; // Declare debug()
// Check if the passed variable can be split.
// Even if this function returns true, the variable may not be split
// because the access to the variable cannot be determined statically.
static bool canSplit(const AstVar* nodep) {
const std::pair<uint32_t, uint32_t> dim = nodep->dtypep()->dimensions(false);
// Public variable cannot be split.
// at least one unpacked dimension must exist
return dim.second >= 1 && !nodep->isSigPublic();
}
};
//######################################################################
// Split packed variables
// Split variable
class SplitNewVar {
int m_lsb; // lsb in the original bitvector
int m_bitwidth;
AstVar* m_varp; // the LSB of this variable is always 0, not m_lsb
public:
SplitNewVar(int lsb, int bitwidth, AstVar* varp = NULL)
: m_lsb(lsb)
, m_bitwidth(bitwidth)
, m_varp(varp) {}
int lsb() const { return m_lsb; }
int msb() const { return m_lsb + m_bitwidth - 1; }
int bitwidth() const { return m_bitwidth; }
void varp(AstVar* vp) {
UASSERT_OBJ(!m_varp, m_varp, "must be NULL");
m_varp = vp;
}
AstVar* varp() const { return m_varp; }
struct Match {
bool operator()(int bit, const SplitNewVar& a) const {
return bit < a.m_lsb + a.m_bitwidth;
}
};
};
// one Entry instance for an AstVarRef instance
class PackedVarRefEntry {
AstNode* m_nodep; // either AstSel or AstVarRef is expected.
int m_lsb;
int m_bitwidth;
public:
PackedVarRefEntry(AstSel* selp, int lsb, int bitwidth)
: m_nodep(selp)
, m_lsb(lsb)
, m_bitwidth(bitwidth) {}
PackedVarRefEntry(AstVarRef* refp, int lsb, int bitwidth)
: m_nodep(refp)
, m_lsb(lsb)
, m_bitwidth(bitwidth) {}
AstNode* nodep() const { return m_nodep; }
int lsb() const { return m_lsb; }
int msb() const { return m_lsb + m_bitwidth - 1; }
int bitwidth() const { return m_bitwidth; }
void replaceNodeWith(AstNode* nodep) {
m_nodep->replaceWith(nodep);
m_nodep->deleteTree(); VL_DANGLING(m_nodep);
}
};
// How a variable is used
class PackedVarRef {
struct SortByFirst {
bool operator()(const std::pair<int, bool>& a, const std::pair<int, bool>& b) const {
if (a.first == b.first) return a.second < b.second;
return a.first < b.first;
}
};
std::vector<PackedVarRefEntry> m_lhs, m_rhs;
AstBasicDType* m_basicp; // cache the ptr since varp->dtypep()->basicp() is expensive
public:
typedef std::vector<PackedVarRefEntry>::iterator iterator;
typedef std::vector<PackedVarRefEntry>::const_iterator const_iterator;
std::vector<PackedVarRefEntry>& lhs() { return m_lhs; }
std::vector<PackedVarRefEntry>& rhs() { return m_rhs; }
explicit PackedVarRef(AstVar* varp)
: m_basicp(varp->dtypep()->basicp()) {}
void append(const PackedVarRefEntry& e, bool lvalue) {
if (lvalue)
m_lhs.push_back(e);
else
m_rhs.push_back(e);
}
const AstBasicDType* basicp() const { return m_basicp; }
// make a plan for variables after split
// when skipUnused==true, split variable for unread bits will not be created.
std::vector<SplitNewVar> splitPlan(bool skipUnused) const {
std::vector<SplitNewVar> plan;
std::vector<std::pair<int, bool> > points; // <bit location, is end>
points.reserve(m_lhs.size() * 2 + 2); // 2 points will be added per one PackedVarRefEntry
for (const_iterator it = m_lhs.begin(), itend = m_lhs.end(); it != itend; ++it) {
points.push_back(std::make_pair(it->lsb(), false)); // start of a region
points.push_back(std::make_pair(it->msb() + 1, true)); // end of a region
}
if (skipUnused && !m_rhs.empty()) { // range to be read must be kept, so add points here
int lsb = m_basicp->msb() + 1, msb = m_basicp->lsb() - 1;
for (size_t i = 0; i < m_rhs.size(); ++i) {
lsb = std::min(lsb, m_rhs[i].lsb());
msb = std::max(msb, m_rhs[i].msb());
}
UASSERT_OBJ(lsb <= msb, m_basicp, "lsb:" << lsb << " msb:" << msb << " are wrong");
points.push_back(std::make_pair(lsb, false));
points.push_back(std::make_pair(msb + 1, true));
}
if (!skipUnused) { // all bits are necessary
points.push_back(std::make_pair(m_basicp->lsb(), false));
points.push_back(std::make_pair(m_basicp->msb() + 1, true));
}
std::sort(points.begin(), points.end(), SortByFirst());
// scan the sorted points and sub bitfields
int refcount = 0;
for (size_t i = 0; i + 1 < points.size(); ++i) {
const int bitwidth = points[i + 1].first - points[i].first;
if (points[i].second)
--refcount; // end of a region
else
++refcount; // start of a region
UASSERT(refcount >= 0, "refcounut must not be negative");
if (bitwidth == 0 || refcount == 0) continue; // vacant region
plan.push_back(SplitNewVar(points[i].first, bitwidth));
}
return plan;
}
};
class SplitPackedVarVisitor : public AstNVisitor {
AstNetlist* m_netp;
AstNodeModule* m_modp; // current module (just for log)
int m_numSplit; // total number of split variable
bool m_isLhs; // true when traversing LHS of assignment
// key:variable to be split. value:location where the variable is referenced.
vl_unordered_map<AstVar*, PackedVarRef> m_refs;
virtual void visit(AstNode* nodep) VL_OVERRIDE { iterateChildren(nodep); }
virtual void visit(AstNodeAssign* nodep) VL_OVERRIDE {
UASSERT_OBJ(m_isLhs == false, nodep, "unexpected nested assign");
m_isLhs = true;
iterate(nodep->lhsp());
m_isLhs = false;
iterate(nodep->rhsp());
}
virtual void visit(AstNodeModule* nodep) VL_OVERRIDE {
UASSERT_OBJ(m_modp == NULL, m_modp, "Nested module declration");
m_modp = nodep;
UINFO(3, "Start analyzing module " << nodep->prettyName() << '\n');
std::vector<std::pair<AstPragma*, AstVar*> > vars = ScanPragmaVisitor::scan(nodep);
for (size_t i = 0; i < vars.size(); ++i) {
AstPragma* pragmap = vars[i].first;
AstVar* varp = vars[i].second;
if (pragmap->pragType() != AstPragmaType::SPLIT_VAR) continue; // nothing to do
UASSERT_OBJ(varp, pragmap,
"Unexpected pragma must have been consumed in SplitUnpackedVarVisitor");
if (!canSplit(varp, true)) {
varp->v3warn(SPLITVAR,
"Pragma split_var is specified on a variable whose type is "
"unsupported or public. "
"Packed portion must be an aggregate type of bit or logic.");
} else { // finally find a good candidate
UINFO(3, varp->prettyNameQ() << " is added to candidate list.\n");
m_refs.insert(std::make_pair(varp, PackedVarRef(varp)));
}
// consume the pragma here anyway.
pragmap->unlinkFrBack()->deleteTree(); VL_DANGLING(vars[i].first);
}
iterateChildren(nodep);
split();
m_modp = NULL;
}
virtual void visit(AstVarRef* nodep) VL_OVERRIDE {
AstVar* varp = nodep->varp();
vl_unordered_map<AstVar*, PackedVarRef>::iterator refit = m_refs.find(varp);
if (refit == m_refs.end()) return; // variable without split_var pragma
UASSERT_OBJ(nodep->lvalue() == m_isLhs, nodep,
(m_isLhs ? 'l' : 'r') << "value is expected");
const AstBasicDType* basicp = refit->second.basicp();
refit->second.append(PackedVarRefEntry(nodep, basicp->lsb(), basicp->width()), m_isLhs);
}
virtual void visit(AstSel* nodep) VL_OVERRIDE {
AstVarRef* vrefp = VN_CAST(nodep->fromp(), VarRef);
if (!vrefp) return;
AstVar* varp = vrefp->varp();
vl_unordered_map<AstVar*, PackedVarRef>::iterator refit = m_refs.find(varp);
if (refit == m_refs.end()) return; // variable without split_var pragma
AstConst* consts[2] = {VN_CAST(nodep->lsbp(), Const), VN_CAST(nodep->widthp(), Const)};
if (consts[0] && consts[1]) { // OK
refit->second.append(
PackedVarRefEntry(nodep, consts[0]->toSInt() + refit->second.basicp()->lsb(),
consts[1]->toUInt()),
m_isLhs);
} else {
nodep->v3warn(SPLITVAR, "Variable "
<< vrefp->prettyNameQ()
<< " will not be split"
" because bit range cannot be determined statically.");
if(!consts[0]) UINFO(4, "LSB " << nodep->lsbp() << " is expected to be constant, but not\n");
if(!consts[1]) UINFO(4, "WIDTH " << nodep->widthp() << " is expected to be constant, but not\n");
m_refs.erase(varp);
}
}
// extract necessary bit range from a newly created variable to meet ref
static AstNode* extractBits(const PackedVarRefEntry& ref, const SplitNewVar& var, bool lvalue) {
AstVarRef* refp = new AstVarRef(ref.nodep()->fileline(), var.varp(), lvalue);
if (ref.lsb() <= var.lsb() && var.msb() <= ref.msb()) { // use the entire bits
return refp;
} else { // use slice
const int lsb = std::max(ref.lsb(), var.lsb());
const int msb = std::min(ref.msb(), var.msb());
const int bitwidth = msb + 1 - lsb;
UINFO(4, var.varp()->prettyNameQ() << "[" << msb << ":" << lsb << "] used for "
<< ref.nodep()->prettyNameQ() << '\n');
// LSB of varp is always 0. "lsb - var.lsb()" means this. see also SplitNewVar
AstSel* selp = new AstSel(ref.nodep()->fileline(), refp, lsb - var.lsb(), bitwidth);
return selp;
}
}
// The actual splitting operation is done in this function.
void split() {
for (vl_unordered_map<AstVar*, PackedVarRef>::iterator it = m_refs.begin(),
it_end = m_refs.end();
it != it_end; ++it) {
AstVar* varp = it->first;
const AstBasicDType* basicp = it->second.basicp();
UINFO(3, "In module " << m_modp->name() << " var " << varp->prettyNameQ()
<< " which has " << it->second.lhs().size() << " lhs refs and "
<< it->second.rhs().size() << " rhs refs will be split.\n");
typedef std::vector<SplitNewVar> NewVars; // sorted by its lsb
NewVars vars = it->second.splitPlan(!varp->isTrace()); // if traced, all bit must be kept
if (vars.empty()) continue;
// Add the split variables
for (size_t i = 0; i < vars.size(); ++i) {
SplitNewVar* newvarp = &vars[i];
int left = newvarp->msb(), right = newvarp->lsb();
if (basicp->littleEndian()) std::swap(left, right);
const std::string name = varp->name() + "__BRA__" + AstNode::encodeNumber(left)
+ AstNode::encodeName(":") + AstNode::encodeNumber(right)
+ "__KET__";
AstBasicDType* dtypep;
switch (basicp->keyword()) {
case AstBasicDTypeKwd::BIT:
dtypep = new AstBasicDType(varp->subDTypep()->fileline(), VFlagBitPacked(),
newvarp->bitwidth());
break;
case AstBasicDTypeKwd::LOGIC:
dtypep = new AstBasicDType(varp->subDTypep()->fileline(), VFlagLogicPacked(),
newvarp->bitwidth());
break;
default: UASSERT_OBJ(false, basicp, "Only bit and logic are allowed");
}
dtypep->rangep(new AstRange(varp->fileline(), newvarp->msb(), newvarp->lsb()));
dtypep->rangep()->littleEndian(basicp->littleEndian());
newvarp->varp(new AstVar(varp->fileline(), varp->varType(), name, dtypep));
// newvarp->varp()->trace(varp->isTrace()); // enable this line to trace split variable directly
m_netp->typeTablep()->addTypesp(dtypep);
varp->addNextHere(newvarp->varp());
UINFO(4, newvarp->varp()->prettyNameQ()
<< " is added for " << varp->prettyNameQ() << '\n');
}
for (int lvalue = 0; lvalue <= 1; ++lvalue) { // refer the new split variables
std::vector<PackedVarRefEntry>& refs = lvalue ? it->second.lhs() : it->second.rhs();
for (PackedVarRef::iterator refit = refs.begin(), refitend = refs.end();
refit != refitend; ++refit) {
NewVars::const_iterator varit = std::upper_bound(
vars.begin(), vars.end(), refit->lsb(), SplitNewVar::Match());
UASSERT_OBJ(varit != vars.end(), refit->nodep(), "Not found");
UASSERT(!(varit->msb() < refit->lsb() || refit->msb() < varit->lsb()),
"wrong search result");
AstNode* prev = extractBits(*refit, *varit, lvalue);
for (int residue = refit->msb() - varit->msb(); residue > 0;
residue -= varit->bitwidth()) {
++varit;
UASSERT_OBJ(varit != vars.end(), refit->nodep(),
"not enough split variables");
AstNode* bitsp = extractBits(*refit, *varit, lvalue);
prev = new AstConcat(refit->nodep()->fileline(), bitsp, prev);
}
refit->replaceNodeWith(prev);
UASSERT_OBJ(varit->msb() >= refit->msb(), varit->varp(), "Out of range");
}
}
if (vars.size() == 1) {
vars.front().varp()->trace(varp->isTrace());
} else if (varp->isTrace()) {
// Let's create a dedicated variable for trace which is concat of split variables
AstVar* traceVar = new AstVar(varp->fileline(), varp->varType(), varp->name(), varp->dtypep());
traceVar->trace(true);
varp->addNextHere(traceVar);
AstNode* rhs = new AstVarRef(vars.front().varp()->fileline(), vars.front().varp(), false);
for (size_t i = 1; i < vars.size(); ++i) {
rhs = new AstConcat(varp->fileline(),
new AstVarRef(varp->fileline(), vars[i].varp(), false),
rhs);
}
AstAssignW* assignp = new AstAssignW(varp->fileline(), new AstVarRef(varp->fileline(), traceVar, true), rhs);
traceVar->addNextHere(assignp);
}
varp->unlinkFrBack()->deleteTree(); VL_DANGLING(varp);
++m_numSplit;
}
m_refs.clear(); // done
}
public:
explicit SplitPackedVarVisitor(AstNetlist* nodep)
: m_netp(nodep)
, m_modp(NULL)
, m_numSplit(0)
, m_isLhs(false) {
iterate(nodep);
}
~SplitPackedVarVisitor() {
UASSERT(m_refs.empty(), "Don't forget to call split()");
V3Stats::addStat("SplitVar, Split packed variables", m_numSplit);
}
// Check if the passed variable can be split.
// Even if this function returns true, the variable may not be split
// when the access to the variable cannot be determined statically.
static bool canSplit(const AstVar* nodep, bool checkUnpacked) {
if (AstBasicDType* const basicp = nodep->dtypep()->basicp()) {
const std::pair<uint32_t, uint32_t> dim = nodep->dtypep()->dimensions(false);
// unpacked array will be split in SplitUnpackedVarVisitor() beforehand.
return (!checkUnpacked || dim.second == 0) && nodep->dtypep()->widthMin() > 1
&& basicp->isBitLogic() // floating point and string are not supported
&& !nodep->isSigPublic();
}
return false;
}
VL_DEBUG_FUNC; // Declare debug()
};
//######################################################################
// Split class functions
void V3SplitVar::splitUnpackedVariable(AstNetlist* nodep) {
UINFO(2, __FUNCTION__ << ": " << endl);
// SplitUnpackedVarVisitor collapses one-dimension per one scan. so repeat until nothing to do.
for (int trial = 0, done = 0; done == 0; ++trial) {
{
SplitUnpackedVarVisitor visitor(nodep, trial == 0);
UINFO(3, visitor.numSplit() << " variables are split in trial " << trial << '\n');
if (visitor.numSplit() == 0) done = 1; // nothing to do anymore
} // Destruct before checking
V3Global::dumpCheckGlobalTree("split_var", 0, v3Global.opt.dumpTreeLevel(__FILE__) >= 9);
}
}
void V3SplitVar::splitPackedVariable(AstNetlist* nodep) {
UINFO(2, __FUNCTION__ << ": " << endl);
{
SplitPackedVarVisitor visitor(nodep);
} // Destruct before checking
V3Global::dumpCheckGlobalTree("split_var", 0, v3Global.opt.dumpTreeLevel(__FILE__) >= 9);
}
bool V3SplitVar::canSplitVar(const AstVar* varp) {
return SplitUnpackedVarVisitor::canSplit(varp) || SplitPackedVarVisitor::canSplit(varp, false);
}
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