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Internals: Add $past variable statistic

This commit is contained in:
Wilson Snyder 2025-08-23 21:10:46 -04:00
parent b226be7f98
commit 7affb3e580
3 changed files with 23 additions and 14 deletions
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8
src/V3Assert.cpp
View File

@ -23,7 +23,7 @@
VL_DEFINE_DEBUG_FUNCTIONS;
//######################################################################
// Assert class functions
// AssertVisitor
class AssertVisitor final : public VNVisitor {
// CONSTANTS
@ -48,6 +48,7 @@ class AssertVisitor final : public VNVisitor {
VDouble0 m_statAsNotImm; // Statistic tracking
VDouble0 m_statAsImm; // Statistic tracking
VDouble0 m_statAsFull; // Statistic tracking
VDouble0 m_statPastVars; // Statistic tracking
bool m_inSampled = false; // True inside a sampled expression
// METHODS
@ -466,9 +467,13 @@ class AssertVisitor final : public VNVisitor {
= new AstAlways{nodep->fileline(), VAlwaysKwd::ALWAYS, sentreep, nullptr};
m_modp->addStmtsp(alwaysp);
for (uint32_t i = 0; i < ticks; ++i) {
// TODO recognize AstVarRef is getting delayed and share variables between
// $pasts with same reference (or same expression). Saves downstream
// optimizations from identifying and removing duplication.
AstVar* const outvarp = new AstVar{
nodep->fileline(), VVarType::MODULETEMP,
"_Vpast_" + cvtToStr(m_modPastNum++) + "_" + cvtToStr(i), inp->dtypep()};
++m_statPastVars;
m_modp->addStmtsp(outvarp);
AstNode* const assp = new AstAssignDly{
nodep->fileline(), new AstVarRef{nodep->fileline(), outvarp, VAccess::WRITE}, inp};
@ -719,6 +724,7 @@ public:
V3Stats::addStat("Assertions, assert immediate statements", m_statAsImm);
V3Stats::addStat("Assertions, cover statements", m_statCover);
V3Stats::addStat("Assertions, full/parallel case", m_statAsFull);
V3Stats::addStat("Assertions, $past variables", m_statPastVars);
}
};

24
src/V3AssertPre.cpp
View File

@ -461,9 +461,9 @@ private:
if (exprp->width() > 1) exprp = new AstSel{fl, exprp, 0, 1};
AstSenTree* sentreep = nodep->sentreep();
if (sentreep) sentreep->unlinkFrBack();
AstNodeExpr* const past = new AstPast{fl, exprp};
past->dtypeFrom(exprp);
exprp = new AstAnd{fl, past, new AstNot{fl, exprp->cloneTreePure(false)}};
AstNodeExpr* const pastp = new AstPast{fl, exprp};
pastp->dtypeFrom(exprp);
exprp = new AstAnd{fl, pastp, new AstNot{fl, exprp->cloneTreePure(false)}};
exprp->dtypeSetBit();
nodep->replaceWith(exprp);
nodep->sentreep(newSenTree(nodep, sentreep));
@ -482,9 +482,9 @@ private:
if (exprp->width() > 1) exprp = new AstSel{fl, exprp, 0, 1};
AstSenTree* sentreep = nodep->sentreep();
if (sentreep) sentreep->unlinkFrBack();
AstNodeExpr* const past = new AstPast{fl, exprp};
past->dtypeFrom(exprp);
exprp = new AstAnd{fl, new AstNot{fl, past}, exprp->cloneTreePure(false)};
AstNodeExpr* const pastp = new AstPast{fl, exprp};
pastp->dtypeFrom(exprp);
exprp = new AstAnd{fl, new AstNot{fl, pastp}, exprp->cloneTreePure(false)};
exprp->dtypeSetBit();
nodep->replaceWith(exprp);
nodep->sentreep(newSenTree(nodep, sentreep));
@ -497,9 +497,9 @@ private:
AstNodeExpr* exprp = nodep->exprp()->unlinkFrBack();
AstSenTree* sentreep = nodep->sentreep();
if (sentreep) sentreep->unlinkFrBack();
AstNodeExpr* const past = new AstPast{fl, exprp};
past->dtypeFrom(exprp);
exprp = new AstEq{fl, past, exprp->cloneTreePure(false)};
AstNodeExpr* const pastp = new AstPast{fl, exprp};
pastp->dtypeFrom(exprp);
exprp = new AstEq{fl, pastp, exprp->cloneTreePure(false)};
exprp->dtypeSetBit();
nodep->replaceWith(exprp);
nodep->sentreep(newSenTree(nodep, sentreep));
@ -515,9 +515,9 @@ private:
if (m_disablep) lhsp = new AstAnd{fl, new AstNot{fl, m_disablep}, lhsp};
AstNodeExpr* const past = new AstPast{fl, lhsp};
past->dtypeFrom(lhsp);
AstNodeExpr* const exprp = new AstOr{fl, new AstNot{fl, past}, rhsp};
AstNodeExpr* const pastp = new AstPast{fl, lhsp};
pastp->dtypeFrom(lhsp);
AstNodeExpr* const exprp = new AstOr{fl, new AstNot{fl, pastp}, rhsp};
exprp->dtypeSetBit();
nodep->replaceWith(exprp);
nodep->sentreep(newSenTree(nodep));

5
test_regress/t/t_past.py
View File

@ -11,8 +11,11 @@ import vltest_bootstrap
test.scenarios('simulator')
test.compile()
test.compile(verilator_flags2=['--stats'])
test.execute()
# Check that $past shared common variables
test.file_grep(test.stats, r'Assertions, \$past variables\s+(\d+)', 11)
test.passes()