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DFG: handle simple always blocks

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This commit is contained in:
Geza Lore 2022-10-01 12:28:16 +01:00
parent 84b9502af4
commit 2a12b052f2
6 changed files with 76 additions and 12 deletions
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2
docs/gen/ex_DIDNOTCONVERGE_msg.rst
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@ -1,5 +1,5 @@
.. comment: generated by t_lint_didnotconverge_bad
.. code-block::
-V{t#,#} 'stl' region trigger index 1 is active: @([hybrid] b)
-V{t#,#} 'stl' region trigger index 1 is active: @([hybrid] a)
%Error: t/t_lint_didnotconverge_bad.v:7: Settle region did not converge.

11
src/V3Delayed.cpp
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@ -109,6 +109,11 @@ private:
// METHODS
const AstNode* containingAssignment(const AstNode* nodep) {
while (nodep && !VN_IS(nodep, NodeAssign)) nodep = nodep->backp();
return nodep;
}
void markVarUsage(AstNodeVarRef* nodep, bool blocking) {
// Ignore if warning is disabled on this reference (used by V3Force).
if (nodep->fileline()->warnIsOff(V3ErrorCode::BLKANDNBLK)) return;
@ -122,8 +127,10 @@ private:
} else {
const bool last_was_blocking = lastrefp->user5();
if (last_was_blocking != blocking) {
const AstNode* const nonblockingp = blocking ? nodep : lastrefp;
const AstNode* const blockingp = blocking ? lastrefp : nodep;
const AstNode* nonblockingp = blocking ? nodep : lastrefp;
if (const AstNode* np = containingAssignment(nonblockingp)) nonblockingp = np;
const AstNode* blockingp = blocking ? lastrefp : nodep;
if (const AstNode* np = containingAssignment(blockingp)) blockingp = np;
vscp->v3warn(
BLKANDNBLK,
"Unsupported: Blocked and non-blocking assignments to same variable: "

63
src/V3DfgAstToDfg.cpp
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@ -212,7 +212,7 @@ class AstToDfgVisitor final : public VNVisitor {
return false;
}
bool convertEquation(AstNode* nodep, AstNode* lhsp, AstNode* rhsp) {
bool convertEquation(AstNode* nodep, FileLine* flp, AstNode* lhsp, AstNode* rhsp) {
UASSERT_OBJ(m_uncommittedVertices.empty(), nodep, "Should not nest");
// Currently cannot handle direct assignments between unpacked types. These arise e.g.
@ -243,7 +243,7 @@ class AstToDfgVisitor final : public VNVisitor {
return false;
}
if (!convertAssignment(nodep->fileline(), lhsp, getVertex(rhsp))) {
if (!convertAssignment(flp, lhsp, getVertex(rhsp))) {
revertUncommittedVertices();
markReferenced(nodep);
return false;
@ -374,7 +374,64 @@ class AstToDfgVisitor final : public VNVisitor {
return;
}
convertEquation(nodep, nodep->lhsp(), nodep->rhsp());
convertEquation(nodep, nodep->fileline(), nodep->lhsp(), nodep->rhsp());
}
void visit(AstAlways* nodep) override {
// Ignore sequential logic, or if there are multiple statements
const VAlwaysKwd kwd = nodep->keyword();
if (nodep->sensesp() || !nodep->isJustOneBodyStmt()
|| (kwd != VAlwaysKwd::ALWAYS && kwd != VAlwaysKwd::ALWAYS_COMB)) {
markReferenced(nodep);
return;
}
AstNode* const stmtp = nodep->stmtsp();
if (AstAssign* const assignp = VN_CAST(stmtp, Assign)) {
++m_ctx.m_inputEquations;
if (assignp->timingControlp()) {
markReferenced(stmtp);
++m_ctx.m_nonRepTiming;
return;
}
convertEquation(nodep, assignp->fileline(), assignp->lhsp(), assignp->rhsp());
} else if (AstIf* const ifp = VN_CAST(stmtp, If)) {
// Will only handle single assignments to the same LHS in both branches
AstAssign* const thenp = VN_CAST(ifp->thensp(), Assign);
AstAssign* const elsep = VN_CAST(ifp->elsesp(), Assign);
if (!thenp || !elsep || thenp->nextp() || elsep->nextp()
|| !thenp->lhsp()->sameTree(elsep->lhsp())) {
markReferenced(stmtp);
return;
}
++m_ctx.m_inputEquations;
if (thenp->timingControlp() || elsep->timingControlp()) {
markReferenced(stmtp);
++m_ctx.m_nonRepTiming;
return;
}
// Create a conditional for the rhs by borrowing the components from the AstIf
AstCond* const rhsp = new AstCond{ifp->fileline(), //
ifp->condp()->unlinkFrBack(), //
thenp->rhsp()->unlinkFrBack(), //
elsep->rhsp()->unlinkFrBack()};
if (!convertEquation(nodep, ifp->fileline(), thenp->lhsp(), rhsp)) {
// Failed to convert. Mark 'rhsp', as 'convertEquation' only marks 'nodep'.
markReferenced(rhsp);
// Put the AstIf back together
ifp->condp(rhsp->condp()->unlinkFrBack());
thenp->rhsp(rhsp->thenp()->unlinkFrBack());
elsep->rhsp(rhsp->elsep()->unlinkFrBack());
}
// Delete the auxiliary conditional
VL_DO_DANGLING(rhsp->deleteTree(), rhsp);
} else {
markReferenced(stmtp);
}
}
void visit(AstVarRef* nodep) override {

2
test_regress/t/t_lint_didnotconverge_bad.out
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@ -1,3 +1,3 @@
-V{t#,#} 'stl' region trigger index 1 is active: @([hybrid] b)
-V{t#,#} 'stl' region trigger index 1 is active: @([hybrid] a)
%Error: t/t_lint_didnotconverge_bad.v:7: Settle region did not converge.
Aborting...

8
test_regress/t/t_order_blkandnblk_bad.out
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@ -1,11 +1,11 @@
%Error-BLKANDNBLK: t/t_order_blkandnblk_bad.v:17:21: Unsupported: Blocked and non-blocking assignments to same variable: 't.array'
17 | logic [1:0][3:0] array;
| ^~~~~
t/t_order_blkandnblk_bad.v:19:16: ... Location of blocking assignment
t/t_order_blkandnblk_bad.v:19:25: ... Location of blocking assignment
19 | always_comb array[0] = i;
| ^~~~~
t/t_order_blkandnblk_bad.v:22:6: ... Location of nonblocking assignment
| ^
t/t_order_blkandnblk_bad.v:22:15: ... Location of nonblocking assignment
22 | array[1] <= array[0];
| ^~~~~
| ^~
... For error description see https://verilator.org/warn/BLKANDNBLK?v=latest
%Error: Exiting due to

2
test_regress/t/t_unopt_converge_unopt_bad.out
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@ -4,6 +4,6 @@
... For warning description see https://verilator.org/warn/UNOPTFLAT?v=latest
... Use "/* verilator lint_off UNOPTFLAT */" and lint_on around source to disable this message.
t/t_unopt_converge.v:19:11: Example path: x
t/t_unopt_converge.v:22:4: Example path: ALWAYS
t/t_unopt_converge.v:23:9: Example path: ASSIGNW
t/t_unopt_converge.v:19:11: Example path: x
%Error: Exiting due to