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Fix MULTIDRIVEN with task and default driver (#4045) (#6858)

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This commit is contained in:
em2machine
2026-01-01 10:20:21 -05:00
committed by GitHub
parent 28d2dc2b70
commit c388e793e0
16 changed files with 1168 additions and 15 deletions
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src/V3Undriven.cpp
+72 -15
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@@ -28,6 +28,7 @@
#include "V3Undriven.h"
#include "V3Stats.h"
#include "V3UndrivenCapture.h"
#include <vector>
@@ -51,6 +52,8 @@ class UndrivenVarEntry final {
const FileLine* m_nodeFileLinep = nullptr; // File line of varref if driven, else nullptr
bool m_underGen = false; // Under a generate
const AstNodeFTaskRef* m_callNodep = nullptr; // Call node if driven via writeSummary
enum : uint8_t { FLAG_USED = 0, FLAG_DRIVEN = 1, FLAG_DRIVEN_ALWCOMB = 2, FLAGS_PER_BIT = 3 };
public:
@@ -278,6 +281,12 @@ public:
}
}
}
void drivenViaCall(const AstNodeFTaskRef* nodep) {
drivenWhole();
if (!m_callNodep) m_callNodep = nodep;
}
const AstNodeFTaskRef* callNodep() const { return m_callNodep; }
};
//######################################################################
@@ -304,6 +313,8 @@ class UndrivenVisitor final : public VNVisitorConst {
const AstAlways* m_alwaysp = nullptr; // Current always of either type
const AstAlways* m_alwaysCombp = nullptr; // Current always if combo, otherwise nullptr
V3UndrivenCapture* const m_capturep = nullptr; // Capture object. 'nullptr' if disabled.
// METHODS
UndrivenVarEntry* getEntryp(AstVar* nodep, int which_user) {
@@ -420,6 +431,16 @@ class UndrivenVisitor final : public VNVisitorConst {
<< " (IEEE 1800-2023 13.5): " << nodep->prettyNameQ());
}
}
// If writeSummary is enabled, task/function definitions are treated as non-executed.
// Their effects are applied at call sites via writeSummary(), so don't let definition
// traversal create phantom "other writes" for MULTIDRIVEN.
if (m_taskp && !m_alwaysp && !m_inContAssign && !m_inInitialStatic && !m_inBBox
&& !m_taskp->dpiExport()) {
AstVar* const retVarp = VN_CAST(m_taskp->fvarp(), Var);
if (!retVarp || nodep->varp() != retVarp) return;
}
for (int usr = 1; usr < (m_alwaysCombp ? 3 : 2); ++usr) {
UndrivenVarEntry* const entryp = getEntryp(nodep->varp(), usr);
const bool fdrv = nodep->access().isWriteOrRW()
@@ -432,7 +453,12 @@ class UndrivenVisitor final : public VNVisitorConst {
if (entryp->isDrivenWhole() && !m_inBBox && !VN_IS(nodep, VarXRef)
&& !VN_IS(nodep->dtypep()->skipRefp(), UnpackArrayDType)
&& nodep->fileline() != entryp->getNodeFileLinep() && !entryp->isUnderGen()
&& entryp->getNodep()) {
&& (entryp->getNodep() || entryp->callNodep())) {
const AstNode* const otherWritep
= entryp->getNodep() ? static_cast<const AstNode*>(entryp->getNodep())
: entryp->callNodep();
if (m_alwaysCombp
&& (!entryp->isDrivenAlwaysCombWhole()
|| (m_alwaysCombp != entryp->getAlwCombp()
@@ -443,20 +469,18 @@ class UndrivenVisitor final : public VNVisitorConst {
<< " (IEEE 1800-2023 9.2.2.2): " << nodep->prettyNameQ() << '\n'
<< nodep->warnOther() << '\n'
<< nodep->warnContextPrimary() << '\n'
<< entryp->getNodep()->warnOther()
<< "... Location of other write\n"
<< entryp->getNodep()->warnContextSecondary());
<< otherWritep->warnOther() << "... Location of other write\n"
<< otherWritep->warnContextSecondary());
}
if (!m_alwaysCombp && entryp->isDrivenAlwaysCombWhole()) {
nodep->v3warn(MULTIDRIVEN,
"Variable also written to in always_comb"
<< " (IEEE 1800-2023 9.2.2.2): " << nodep->prettyNameQ()
<< '\n'
<< nodep->warnOther() << '\n'
<< nodep->warnContextPrimary() << '\n'
<< entryp->getNodep()->warnOther()
<< "... Location of always_comb write\n"
<< entryp->getNodep()->warnContextSecondary());
nodep->v3warn(MULTIDRIVEN, "Variable also written to in always_comb"
<< " (IEEE 1800-2023 9.2.2.2): "
<< nodep->prettyNameQ() << '\n'
<< nodep->warnOther() << '\n'
<< nodep->warnContextPrimary() << '\n'
<< otherWritep->warnOther()
<< "... Location of always_comb write\n"
<< otherWritep->warnContextSecondary());
}
}
entryp->drivenWhole(nodep, nodep->fileline());
@@ -523,10 +547,36 @@ class UndrivenVisitor final : public VNVisitorConst {
iterateChildrenConst(nodep);
if (nodep->keyword() == VAlwaysKwd::ALWAYS_COMB) UINFO(9, " Done " << nodep);
}
void visit(AstNodeFTaskRef* nodep) override {
VL_RESTORER(m_inFTaskRef);
m_inFTaskRef = true;
iterateChildrenConst(nodep);
if (!m_capturep) return;
// If writeSummary is enabled, task/function definitions are treated as non-executed.
// Do not apply writeSummary at calls inside a task definition, or they will look like
// independent drivers (phantom MULTIDRIVEN).
const bool inExecutedContext
= !(m_taskp && !m_alwaysp && !m_inContAssign && !m_inInitialStatic && !m_inBBox
&& !m_taskp->dpiExport());
if (!inExecutedContext) return;
AstNodeFTask* const calleep = nodep->taskp();
if (!calleep) return;
const auto& vars = m_capturep->writeSummary(calleep);
for (AstVar* const varp : vars) {
for (int usr = 1; usr < (m_alwaysCombp ? 3 : 2); ++usr) {
UndrivenVarEntry* const entryp = getEntryp(varp, usr);
entryp->drivenViaCall(nodep);
if (m_alwaysCombp)
entryp->drivenAlwaysCombWhole(m_alwaysCombp, m_alwaysCombp->fileline());
}
}
}
void visit(AstNodeFTask* nodep) override {
@@ -556,7 +606,11 @@ class UndrivenVisitor final : public VNVisitorConst {
public:
// CONSTRUCTORS
explicit UndrivenVisitor(AstNetlist* nodep) { iterateConst(nodep); }
explicit UndrivenVisitor(AstNetlist* nodep, V3UndrivenCapture* capturep)
: m_capturep{capturep} {
iterateConst(nodep);
}
~UndrivenVisitor() override {
for (UndrivenVarEntry* ip : m_entryps[1]) ip->reportViolations();
for (int usr = 1; usr < 3; ++usr) {
@@ -570,6 +624,9 @@ public:
void V3Undriven::undrivenAll(AstNetlist* nodep) {
UINFO(2, __FUNCTION__ << ":");
{ UndrivenVisitor{nodep}; }
V3UndrivenCapture capture{nodep};
UndrivenVisitor{nodep, &capture};
if (v3Global.opt.stats()) V3Stats::statsStage("undriven");
}