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Support side effects of form variable[index_function()]++.

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This commit is contained in:
Wilson Snyder
2025-01-08 19:37:20 -05:00
parent ff244c1d1f
commit 44f49669a3
9 changed files with 172 additions and 20 deletions
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src/V3LinkInc.cpp
+67 -3
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@@ -27,6 +27,7 @@
// Create a temporary __VIncrementX variable, assign the value of
// of the current variable (after the operation) to it. Substitute
// The original variable with the temporary one in the statement.
//
// prepost_stmt_visit
// PREADD/PRESUB/POSTADD/POSTSUB
// Increment/decrement the current variable by the given value.
@@ -34,6 +35,12 @@
// the pre/post operations are treated equally and there is no
// need for a temporary variable.
//
// prepost_stmt_sel_visit
// For e.g. 'array[something_with_side_eff]++', common in UVM etc
// PREADD/PRESUB/POSTADD/POSTSUB
// Create temporary with array index.
// Increment/decrement using index of the temporary.
//
//*************************************************************************
#include "V3PchAstNoMT.h" // VL_MT_DISABLED_CODE_UNIT
@@ -205,12 +212,69 @@ class LinkIncVisitor final : public VNVisitor {
void visit(AstPropSpec* nodep) override { unsupported_visit(nodep); }
void prepost_visit(AstNodeTriop* nodep) {
// Check if we are underneath a statement
if (!m_insStmtp) {
prepost_stmt_visit(nodep);
AstSelBit* const selbitp = VN_CAST(nodep->thsp(), SelBit);
if (!m_insStmtp && selbitp && VN_IS(selbitp->fromp(), NodeVarRef)
&& !selbitp->bitp()->isPure()) {
prepost_stmt_sel_visit(nodep);
} else {
prepost_expr_visit(nodep);
// Purity check was deferred at creation in verilog.y, check now
nodep->thsp()->purityCheck();
if (!m_insStmtp) {
prepost_stmt_visit(nodep);
} else {
prepost_expr_visit(nodep);
}
}
}
void prepost_stmt_sel_visit(AstNodeTriop* nodep) {
// Special case array[something]++, see comments at file top
// if (debug() >= 9) nodep->dumpTree("-pp-stmt-sel-in: ");
iterateChildren(nodep);
AstConst* const constp = VN_AS(nodep->lhsp(), Const);
UASSERT_OBJ(nodep, constp, "Expecting CONST");
AstConst* const newconstp = constp->cloneTree(true);
AstSelBit* const rdSelbitp = VN_CAST(nodep->rhsp(), SelBit);
AstNodeExpr* const rdFromp = rdSelbitp->fromp()->unlinkFrBack();
AstNodeExpr* const rdBitp = rdSelbitp->bitp()->unlinkFrBack();
AstSelBit* const wrSelbitp = VN_CAST(nodep->thsp(), SelBit);
AstNodeExpr* const wrFromp = wrSelbitp->fromp()->unlinkFrBack();
// Prepare a temporary variable
FileLine* const fl = nodep->fileline();
const string name = "__VincIndex"s + cvtToStr(++m_modIncrementsNum);
AstVar* const varp = new AstVar{
fl, VVarType::BLOCKTEMP, name, VFlagChildDType{},
new AstRefDType{fl, AstRefDType::FlagTypeOfExpr{}, rdBitp->cloneTree(true)}};
if (m_ftaskp) varp->funcLocal(true);
// Declare the variable
insertOnTop(varp);
// Define what operation will we be doing
AstAssign* const varAssignp
= new AstAssign{fl, new AstVarRef{fl, varp, VAccess::WRITE}, rdBitp};
AstNode* const newp = varAssignp;
AstNodeExpr* const valuep
= new AstSelBit{fl, rdFromp, new AstVarRef{fl, varp, VAccess::READ}};
AstNodeExpr* const storeTop
= new AstSelBit{fl, wrFromp, new AstVarRef{fl, varp, VAccess::READ}};
AstAssign* assignp;
if (VN_IS(nodep, PreSub) || VN_IS(nodep, PostSub)) {
assignp = new AstAssign{nodep->fileline(), storeTop,
new AstSub{nodep->fileline(), valuep, newconstp}};
} else {
assignp = new AstAssign{nodep->fileline(), storeTop,
new AstAdd{nodep->fileline(), valuep, newconstp}};
}
newp->addNext(assignp);
// if (debug() >= 9) newp->dumpTreeAndNext("-pp-stmt-sel-new: ");
nodep->replaceWith(newp);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
}
void prepost_stmt_visit(AstNodeTriop* nodep) {
iterateChildren(nodep);
AstConst* const constp = VN_AS(nodep->lhsp(), Const);