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Correctly schedule combinational logic driven from DPI exports.

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Fixes #3429.
This commit is contained in:
Geza Lore
2022-07-14 15:35:49 +01:00
parent ff1b9930fc
commit 6a7bda6910
15 changed files with 330 additions and 117 deletions
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src/V3Task.cpp
+22 -37
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@@ -1055,7 +1055,7 @@ private:
}
}
AstVarScope* makeDpiExporTrigger() {
AstVarScope* getDpiExporTrigger() {
AstNetlist* const netlistp = v3Global.rootp();
AstVarScope* dpiExportTriggerp = netlistp->dpiExportTriggerp();
if (!dpiExportTriggerp) {
@@ -1271,52 +1271,37 @@ private:
// Mark all non-local variables written by the DPI exported function as being updated
// by DPI exports. This ensures correct ordering and change detection later.
// Gather non-local variables written by the exported function
std::vector<AstVarScope*> writtenps;
{
const VNUser5InUse user5InUse; // AstVarScope::user5 -> Already added variable
cfuncp->foreach<AstVarRef>([&writtenps](AstVarRef* refp) {
if (refp->access().isReadOnly()) return; // Ignore read reference
AstVarScope* const varScopep = refp->varScopep();
if (varScopep->user5()) return; // Ignore already added variable
varScopep->user5(true); // Mark as already added
// Note: We are ignoring function locals as they should not be referenced
// anywhere outside of the enclosing AstCFunc, and therefore they are
// irrelevant for code ordering. This is an optimization to avoid adding
// useless nodes to the ordering graph in V3Order.
if (varScopep->varp()->isFuncLocal()) return;
writtenps.push_back(varScopep);
});
}
// Mark non-local variables written by the exported function
bool writesNonLocals = false;
cfuncp->foreach<AstVarRef>([&writesNonLocals](AstVarRef* refp) {
if (refp->access().isReadOnly()) return; // Ignore read reference
AstVar* const varp = refp->varScopep()->varp();
// We are ignoring function locals as they should not be referenced anywhere
// outside the enclosing AstCFunc, hence they are irrelevant for code ordering.
if (varp->isFuncLocal()) return;
// Mark it as written by DPI export
varp->setWrittenByDpi();
// Remember we had some
writesNonLocals = true;
});
if (!writtenps.empty()) {
AstVarScope* const dpiExportTriggerp = makeDpiExporTrigger();
FileLine* const fl = cfuncp->fileline();
// If this DPI export writes some non-local variables, set the DPI Export Trigger flag
// in the function.
if (writesNonLocals) {
AstVarScope* const dpiExportTriggerp = getDpiExporTrigger();
FileLine* const flp = cfuncp->fileline();
// Set DPI export trigger flag every time the DPI export is called.
AstAssign* const assignp
= new AstAssign{fl, new AstVarRef{fl, dpiExportTriggerp, VAccess::WRITE},
new AstConst{fl, AstConst::BitTrue{}}};
= new AstAssign{flp, new AstVarRef{flp, dpiExportTriggerp, VAccess::WRITE},
new AstConst{flp, AstConst::BitTrue{}}};
// Add as first statement (to avoid issues with early returns) to exported function
if (cfuncp->stmtsp()) {
cfuncp->stmtsp()->addHereThisAsNext(assignp);
} else {
cfuncp->addStmtsp(assignp);
}
// Add an always block sensitive to the DPI export trigger flag, and add an
// AstDpiExportUpdated node under it for each variable that are writen by the
// exported function.
AstAlways* const alwaysp = new AstAlways{
fl, VAlwaysKwd::ALWAYS,
new AstSenTree{
fl, new AstSenItem{fl, VEdgeType::ET_DPIEXPORT,
new AstVarRef{fl, dpiExportTriggerp, VAccess::READ}}},
nullptr};
for (AstVarScope* const varScopep : writtenps) {
alwaysp->addStmtp(new AstDpiExportUpdated{fl, varScopep});
}
m_scopep->addActivep(alwaysp);
}
}