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Fix fork scheduling semantics (#6730)

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Signed-off-by: Artur Bieniek <[email protected]>
This commit is contained in:
Artur Bieniek
2025-11-26 15:52:53 +03:00
committed by GitHub
parent f4654a451b
commit 2c5ff3f63f
26 changed files with 401 additions and 63 deletions
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src/V3LinkParse.cpp
+61 -2
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@@ -23,6 +23,7 @@
#include "V3LinkParse.h"
#include "V3Control.h"
#include "V3MemberMap.h"
#include "V3Stats.h"
#include <set>
@@ -46,6 +47,7 @@ class LinkParseVisitor final : public VNVisitor {
// STATE - across all visitors
std::unordered_set<FileLine*> m_filelines; // Filelines that have been seen
VMemberMap m_memberMap; // for lookup of process class methods
// STATE - for current visit position (use VL_RESTORER)
// If set, move AstVar->valuep() initial values to this module
@@ -72,6 +74,9 @@ class LinkParseVisitor final : public VNVisitor {
// STATE - Statistic tracking
VDouble0 m_statModules; // Number of modules seen
bool m_unprotectedStdProcess
= false; // Set when std::process internals were unprotected, we only need to do this once
// METHODS
void cleanFileline(AstNode* nodep) {
if (nodep->user2SetOnce()) return; // Process once
@@ -105,6 +110,21 @@ class LinkParseVisitor final : public VNVisitor {
return "";
}
void unprotectStdProcessHandle() {
if (m_unprotectedStdProcess) return;
m_unprotectedStdProcess = true;
if (!v3Global.opt.protectIds()) return;
if (AstPackage* const stdp = v3Global.rootp()->stdPackagep()) {
if (AstClass* const processp
= VN_CAST(m_memberMap.findMember(stdp, "process"), Class)) {
if (AstVar* const handlep
= VN_CAST(m_memberMap.findMember(processp, "m_process"), Var)) {
handlep->protect(false);
}
}
}
}
void visitIterateNodeDType(AstNodeDType* nodep) {
if (nodep->user1SetOnce()) return; // Process only once.
cleanFileline(nodep);
@@ -180,6 +200,38 @@ class LinkParseVisitor final : public VNVisitor {
<< nodep->warnContextSecondary());
}
void addForkParentProcess(AstFork* forkp) {
FileLine* const fl = forkp->fileline();
const std::string parentName = "__VforkParent";
AstRefDType* const dtypep = new AstRefDType{fl, "process"};
AstVar* const parentVar
= new AstVar{fl, VVarType::BLOCKTEMP, parentName, VFlagChildDType{}, dtypep};
parentVar->lifetime(VLifetime::AUTOMATIC_EXPLICIT);
AstParseRef* const lhsp = new AstParseRef{fl, parentName, nullptr, nullptr};
AstClassOrPackageRef* const processRefp
= new AstClassOrPackageRef{fl, "process", nullptr, nullptr};
AstParseRef* const selfRefp = new AstParseRef{fl, "self", nullptr, nullptr};
AstDot* const processSelfp = new AstDot{fl, true, processRefp, selfRefp};
AstMethodCall* const callp = new AstMethodCall{fl, processSelfp, "self", nullptr};
AstAssign* const initp = new AstAssign{fl, lhsp, callp};
AstVarRef* const parentRefp = new AstVarRef{fl, parentVar, VAccess::READ};
forkp->parentProcessp(parentRefp);
VNRelinker relinker;
forkp->unlinkFrBack(&relinker);
parentVar->addNextHere(initp);
initp->addNextHere(forkp);
AstBegin* const beginp = new AstBegin{
fl, forkp->name() == "" ? "" : forkp->name() + "__VgetForkParent", parentVar, true};
relinker.relink(beginp);
}
// VISITORS
void visit(AstNodeFTask* nodep) override {
if (nodep->user1SetOnce()) return; // Process only once.
@@ -791,7 +843,11 @@ class LinkParseVisitor final : public VNVisitor {
}
cleanFileline(nodep);
iterateAndNextNull(nodep->stmtsp());
if (AstFork* const forkp = VN_CAST(nodep, Fork)) iterateAndNextNull(forkp->forksp());
if (AstFork* const forkp = VN_CAST(nodep, Fork)) {
iterateAndNextNull(forkp->forksp());
if (!forkp->parentProcessp() && forkp->joinType().joinNone() && forkp->forksp())
addForkParentProcess(forkp);
}
}
void visit(AstCase* nodep) override {
V3Control::applyCase(nodep);
@@ -954,7 +1010,10 @@ class LinkParseVisitor final : public VNVisitor {
public:
// CONSTRUCTORS
explicit LinkParseVisitor(AstNetlist* rootp) { iterate(rootp); }
explicit LinkParseVisitor(AstNetlist* rootp) {
unprotectStdProcessHandle();
iterate(rootp);
}
~LinkParseVisitor() override {
V3Stats::addStatSum(V3Stats::STAT_SOURCE_MODULES, m_statModules);
}