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Internals: Make AstCAwait an AstNodeStmt (#6280) (#7078)

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AstCAwait is only ever uses in statement position, so model it as a
statement. We should never ever have a coroutine that returns a value.
There is no need for it in SV, nor should we rely on it for internals.

Also reworks the fix for V3Life incorrectly constant propagating the
beforeTrig functions (#7072). The property that upsets V3Life is that
a function:
1. Is called from multiple static call sites (multiple AstCCall)
2. Reads model state directly (AstVarRef to non-locals/arguments)

Such function can only be created internally after scheduling (V3Task
throws an unsupported error on a non-inlined function that reads model
state), so added a flag to AstCFunc to mark the dangerous ones for
V3Life.
This commit is contained in:
Geza Lore
2026-02-14 20:15:32 +00:00
committed by GitHub
parent be27811a10
commit a0b89dde8e
9 changed files with 53 additions and 64 deletions
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src/V3Timing.cpp
+14 -23
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@@ -759,9 +759,7 @@ class TimingControlVisitor final : public VNVisitor {
joinp->dtypeSetVoid();
addProcessInfo(joinp);
addDebugInfo(joinp);
AstCAwait* const awaitp = new AstCAwait{flp, joinp};
awaitp->dtypeSetVoid();
forkp->addNextHere(awaitp->makeStmt());
forkp->addNextHere(new AstCAwait{flp, joinp});
}
// `procp` shall be a NodeProcedure/CFunc/Begin and within it vars from `varsp` will be placed.
@@ -907,11 +905,10 @@ class TimingControlVisitor final : public VNVisitor {
void visit(AstNodeCCall* nodep) override {
if (nodep->funcp()->needProcess()) m_hasProcess = true;
if (hasFlags(nodep->funcp(), T_SUSPENDEE) && !nodep->user1SetOnce()) { // If suspendable
VNRelinker relinker;
nodep->unlinkFrBack(&relinker);
AstCAwait* const awaitp = new AstCAwait{nodep->fileline(), nodep};
awaitp->dtypeSetVoid();
relinker.relink(awaitp);
// Calls to suspendables are always void return type, hence parent must be StmtExpr
AstStmtExpr* const stmtp = VN_AS(nodep->backp(), StmtExpr);
stmtp->replaceWith(new AstCAwait{nodep->fileline(), nodep->unlinkFrBack()});
VL_DO_DANGLING(pushDeletep(stmtp), stmtp);
}
iterateChildren(nodep);
}
@@ -948,15 +945,12 @@ class TimingControlVisitor final : public VNVisitor {
addProcessInfo(delayMethodp);
addDebugInfo(delayMethodp);
// Create the co_await
AstCAwait* const awaitp = new AstCAwait{flp, delayMethodp, getCreateDelaySenTree()};
awaitp->dtypeSetVoid();
AstStmtExpr* const awaitStmtp = awaitp->makeStmt();
AstNode* const awaitp = new AstCAwait{flp, delayMethodp, getCreateDelaySenTree()};
// Relink child statements after the co_await
if (nodep->stmtsp()) {
AstNode::addNext<AstNode, AstNode>(awaitStmtp,
nodep->stmtsp()->unlinkFrBackWithNext());
if (AstNode* const stmtsp = nodep->stmtsp()) {
awaitp->addNext(stmtsp->unlinkFrBackWithNext());
}
nodep->replaceWith(awaitStmtp);
nodep->replaceWith(awaitp);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
}
void visit(AstEventControl* nodep) override {
@@ -989,7 +983,6 @@ class TimingControlVisitor final : public VNVisitor {
// Create the co_await
AstCAwait* const awaitEvalp
= new AstCAwait{flp, evalMethodp, getCreateDynamicTriggerSenTree()};
awaitEvalp->dtypeSetVoid();
// Construct the sen expression for this sentree
UASSERT_OBJ(m_senExprBuilderp, nodep, "No SenExprBuilder for this scope");
auto* const assignp = new AstAssign{flp, new AstVarRef{flp, trigvscp, VAccess::WRITE},
@@ -1007,7 +1000,7 @@ class TimingControlVisitor final : public VNVisitor {
= new AstLogNot{flp, new AstVarRef{flp, trigvscp, VAccess::READ}};
AstLoop* const loopp = new AstLoop{flp};
loopp->addStmtsp(new AstLoopTest{flp, loopp, condp});
loopp->addStmtsp(awaitEvalp->makeStmt());
loopp->addStmtsp(awaitEvalp);
// Put pre updates before the trigger check and assignment
for (AstNodeStmt* const stmtp : senResults.m_preUpdates) loopp->addStmtsp(stmtp);
// Then the trigger check and assignment
@@ -1024,14 +1017,14 @@ class TimingControlVisitor final : public VNVisitor {
if (destructivePostUpdate(sentreep)) {
AstCAwait* const awaitPostUpdatep = awaitEvalp->cloneTree(false);
VN_AS(awaitPostUpdatep->exprp(), CMethodHard)->method(VCMethod::SCHED_POST_UPDATE);
loopp->addStmtsp(awaitPostUpdatep->makeStmt());
loopp->addStmtsp(awaitPostUpdatep);
}
// Put the post updates at the end of the loop
for (AstNodeStmt* const stmtp : senResults.m_postUpdates) loopp->addStmtsp(stmtp);
// Finally, await the resumption step in 'act'
AstCAwait* const awaitResumep = awaitEvalp->cloneTree(false);
VN_AS(awaitResumep->exprp(), CMethodHard)->method(VCMethod::SCHED_RESUMPTION);
AstNode::addNext<AstNodeStmt, AstNodeStmt>(loopp, awaitResumep->makeStmt());
AstNode::addNext<AstNodeStmt, AstNodeStmt>(loopp, awaitResumep);
// Replace the event control with the loop
nodep->replaceWith(loopp);
} else {
@@ -1050,8 +1043,7 @@ class TimingControlVisitor final : public VNVisitor {
addEventDebugInfo(triggerMethodp, sentreep);
// Create the co_await
AstCAwait* const awaitp = new AstCAwait{flp, triggerMethodp, sentreep};
awaitp->dtypeSetVoid();
nodep->replaceWith(awaitp->makeStmt());
nodep->replaceWith(awaitp);
}
VL_DO_DANGLING(nodep->deleteTree(), nodep);
}
@@ -1250,8 +1242,7 @@ class TimingControlVisitor final : public VNVisitor {
// callstack
AstCExpr* const foreverp = new AstCExpr{flp, "VlForever{}"};
AstCAwait* const awaitp = new AstCAwait{flp, foreverp};
awaitp->dtypeSetVoid();
nodep->replaceWith(awaitp->makeStmt());
nodep->replaceWith(awaitp);
if (stmtsp) VL_DO_DANGLING(stmtsp->deleteTree(), stmtsp);
VL_DO_DANGLING(condp->deleteTree(), condp);
} else {