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Fix hierarchical NBAs (#6286) (#6300)

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NBAs targeting a variable in a different scope are now allocated
temporary variables for captured values in the scope of the NBA, not the
scope of the target variable.

Fixes #6286
This commit is contained in:
Geza Lore
2025-08-17 19:35:40 +01:00
committed by GitHub
parent b14539569f
commit f6edf26eb2
3 changed files with 167 additions and 10 deletions
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src/V3Delayed.cpp
+36 -10
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@@ -245,7 +245,9 @@ class DelayedVisitor final : public VNVisitor {
// AstVar::user1() -> bool. Set true if already issued MULTIDRIVEN warning
// AstVarRef::user1() -> bool. Set true if target of NBA
// AstAssignDly::user1() -> bool. Set true if already visited
// AstAssignDly::user2p() -> AstVarScope*: Scope this AstAssignDelay is under
// AstNodeModule::user1p() -> std::unorded_map<std::string, AstVar*> temp map via m_varMap
// AstScope::user1() -> int: Temporary counter for this scope
// AstVarScope::user1p() -> VarScopeInfo via m_vscpInfo
// AstVarScope::user2p() -> AstVarRef*: First write reference to the Variable
// AstVarScope::user3p() -> std::vector<WriteReference> via m_writeRefs;
@@ -263,6 +265,7 @@ class DelayedVisitor final : public VNVisitor {
AstActive* m_activep = nullptr; // Current activate
const AstCFunc* m_cfuncp = nullptr; // Current public C Function
AstNodeProcedure* m_procp = nullptr; // Current process
AstScope* m_scopep = nullptr; // Current scope
bool m_inLoop = false; // True in for loops
bool m_inSuspendableOrFork = false; // True in suspendable processes and forks
bool m_ignoreBlkAndNBlk = false; // Suppress delayed assignment BLKANDNBLK
@@ -466,6 +469,7 @@ class DelayedVisitor final : public VNVisitor {
varp = new AstVar{flp, VVarType::BLOCKTEMP, name, dtypep};
modp->addStmtsp(varp);
}
UASSERT_OBJ(varp->dtypep()->isSame(dtypep), flp, "Invalid type for temporary AstVar");
// Create the AstVarScope
AstVarScope* const varscp = new AstVarScope{flp, scopep, varp};
scopep->addVarsp(varscp);
@@ -531,6 +535,21 @@ class DelayedVisitor final : public VNVisitor {
return lhsp;
}
// Create a unique temporary variable name
std::string uniqueTmpName(AstScope* scopep, AstVarScope* vscp, VarScopeInfo& vscpInfo) {
std::stringstream ss;
ss << "__" << vscp->varp()->shortName() + "__v";
// If the assignment is in the same scope as the variable, just
// use the temporary counter of the variable.
if (scopep == vscp->scopep()) {
ss << vscpInfo.m_nTmp++;
} else {
// Otherwise use the temporary counter of the scope of the assignment.
ss << scopep->user1Inc() << "_hierarchical";
}
return ss.str();
}
// Create a temporary variable in the given 'scopep', with the given 'name', and with 'dtypep'
// type, with the bits selected by 'sLsbp'/'sWidthp' set to 'valuep', other bits set to zero.
// Insert new statements before 'insertp'.
@@ -671,11 +690,10 @@ class DelayedVisitor final : public VNVisitor {
void convertSchemeFlagShared(AstAssignDly* nodep, AstVarScope* vscp, VarScopeInfo& vscpInfo) {
UASSERT_OBJ(vscpInfo.m_scheme == Scheme::FlagShared, vscp, "Inconsistent NBA scheme");
FileLine* const flp = vscp->fileline();
AstScope* const scopep = vscp->scopep();
AstScope* const scopep = VN_AS(nodep->user2p(), Scope);
// Base name suffix for signals constructed below
const std::string baseName{"__" + vscp->varp()->shortName() + "__v"
+ std::to_string(vscpInfo.m_nTmp++)};
const std::string baseName = uniqueTmpName(scopep, vscp, vscpInfo);
// Unlink and capture the RHS value
AstNodeExpr* const capturedRhsp
@@ -697,6 +715,8 @@ class DelayedVisitor final : public VNVisitor {
consecutive
// ... that use the same scheme
&& prevVscpInfop->m_scheme == Scheme::FlagShared
// ... and are in the same scope as the target variable
&& scopep == vscp->scopep()
// ... and share the same overall update domain
&& prevVscpInfop->senTreep()->sameTree(vscpInfo.senTreep());
@@ -763,11 +783,10 @@ class DelayedVisitor final : public VNVisitor {
void convertSchemeFlagUnique(AstAssignDly* nodep, AstVarScope* vscp, VarScopeInfo& vscpInfo) {
UASSERT_OBJ(vscpInfo.m_scheme == Scheme::FlagUnique, vscp, "Inconsistent NBA scheme");
FileLine* const flp = vscp->fileline();
AstScope* const scopep = vscp->scopep();
AstScope* const scopep = VN_AS(nodep->user2p(), Scope);
// Base name suffix for signals constructed below
const std::string baseName{"__" + vscp->varp()->shortName() + "__v"
+ std::to_string(vscpInfo.m_nTmp++)};
const std::string baseName = uniqueTmpName(scopep, vscp, vscpInfo);
// Unlink and capture the RHS value
AstNodeExpr* const capturedRhsp
@@ -837,11 +856,10 @@ class DelayedVisitor final : public VNVisitor {
: vscpInfo.m_scheme == Scheme::ValueQueueWhole,
vscp, "Inconsistent NBA scheme");
FileLine* const flp = vscp->fileline();
AstScope* const scopep = vscp->scopep();
AstScope* const scopep = VN_AS(nodep->user2p(), Scope);
// Base name suffix for signals constructed below
const std::string baseName{"__" + vscp->varp()->shortName() + "__v"
+ std::to_string(vscpInfo.m_nTmp++)};
const std::string baseName = uniqueTmpName(scopep, vscp, vscpInfo);
// Unlink and capture the RHS value
AstNodeExpr* const capturedRhsp
@@ -1051,7 +1069,11 @@ class DelayedVisitor final : public VNVisitor {
}
}
}
void visit(AstScope* nodep) override { iterateChildren(nodep); }
void visit(AstScope* nodep) override {
VL_RESTORER(m_scopep);
m_scopep = nodep;
iterateChildren(nodep);
}
void visit(AstCFunc* nodep) override {
VL_RESTORER(m_cfuncp);
m_cfuncp = nodep;
@@ -1169,9 +1191,13 @@ class DelayedVisitor final : public VNVisitor {
}
UASSERT_OBJ(m_procp, nodep, "Delayed assignment not under process");
UASSERT_OBJ(m_activep, nodep, "<= not under sensitivity block");
UASSERT_OBJ(m_scopep, nodep, "<= not under scope");
UASSERT_OBJ(m_inSuspendableOrFork || m_activep->hasClocked(), nodep,
"<= assignment in non-clocked block, should have been converted in V3Active");
// Record scope of this NBA
nodep->user2p(m_scopep);
// Grab the reference to the target of the NBA, also lift ExprStmt statements on the LHS
VL_RESTORER(m_currNbaLhsRefp);
UASSERT_OBJ(!m_currNbaLhsRefp, nodep, "NBAs should not nest");