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Internals: Cleanup case condition lifting (#7768)

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V3Begin used to lift impure case expressions. With V3LiftExpr, this is
now redundant.
This commit is contained in:
Geza Lore
2026-06-12 06:38:21 +01:00
committed by GitHub
parent 0ee25038ac
commit 4555c8b23c
4 changed files with 8 additions and 66 deletions
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src/V3Begin.cpp
+2 -30
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@@ -61,7 +61,6 @@ class BeginVisitor final : public VNVisitor {
// NODE STATE
// AstCase::user1 -> bool, if already purified
V3UniqueNames m_caseTempNames; // For generating unique temporary variable names used by cases
// STATE - across all visitors
BeginState* const m_statep; // Current global state
@@ -75,7 +74,6 @@ class BeginVisitor final : public VNVisitor {
string m_unnamedScope; // Name of begin blocks, including unnamed blocks
int m_ifDepth = 0; // Current if depth
bool m_keepBegins = false; // True if begins should not be inlined
VDouble0 m_statPurifiedCaseExpr; // Count of purified case expressions
// METHODS
@@ -132,7 +130,6 @@ class BeginVisitor final : public VNVisitor {
}
void visit(AstNodeModule* nodep) override {
VL_RESTORER(m_modp);
VL_RESTORER(m_caseTempNames);
m_modp = nodep;
// Rename it (e.g. class under a generate)
if (m_unnamedScope != "") {
@@ -171,7 +168,6 @@ class BeginVisitor final : public VNVisitor {
VL_RESTORER(m_liftedp);
VL_RESTORER(m_namedScope);
VL_RESTORER(m_unnamedScope);
VL_RESTORER(m_caseTempNames);
m_displayScope = dot(m_displayScope, nodep->name());
m_namedScope = "";
m_unnamedScope = "";
@@ -415,29 +411,7 @@ class BeginVisitor final : public VNVisitor {
// any BEGINs, but V3Coverage adds them all under the module itself.
iterateChildren(nodep);
}
void visit(AstCase* nodep) override {
// Introduce temporary variable for AstCase if needed - it is done here and not in V3Case
// because this phase is before V3Scope and V3Case is not. Doing it before V3Scope ensures
// that V3Scope will take care of a scope creation
if (!nodep->exprp()->isPure() && !nodep->user1SetOnce()) {
++m_statPurifiedCaseExpr;
FileLine* const fl = nodep->exprp()->fileline();
AstVar* const varp = new AstVar{fl, VVarType::XTEMP, m_caseTempNames.get(nodep),
nodep->exprp()->dtypep()};
nodep->exprp(new AstExprStmt{fl,
new AstAssign{fl, new AstVarRef{fl, varp, VAccess::WRITE},
nodep->exprp()->unlinkFrBack()},
new AstVarRef{fl, varp, VAccess::READ}});
if (m_ftaskp) {
varp->funcLocal(true);
varp->lifetime(VLifetime::AUTOMATIC_EXPLICIT);
m_ftaskp->stmtsp()->addHereThisAsNext(varp);
} else {
m_modp->stmtsp()->addHereThisAsNext(varp);
}
}
iterateChildren(nodep);
}
void visit(AstCase* nodep) override { iterateChildren(nodep); }
// VISITORS - LINT CHECK
void visit(AstIf* nodep) override { // not AstNodeIf; other types not covered
VL_RESTORER(m_keepBegins);
@@ -464,10 +438,8 @@ class BeginVisitor final : public VNVisitor {
public:
// CONSTRUCTORS
BeginVisitor(AstNetlist* nodep, BeginState* statep)
: m_caseTempNames{"__VCase"}
, m_statep{statep} {
: m_statep{statep} {
iterate(nodep);
V3Stats::addStatSum("Impure case expressions", m_statPurifiedCaseExpr);
}
~BeginVisitor() override = default;
};