verilator/src/V3Slice.cpp
2020-05-31 20:21:07 +01:00

243 lines
12 KiB
C++

// -*- mode: C++; c-file-style: "cc-mode" -*-
//*************************************************************************
// DESCRIPTION: Verilator: Parse module/signal name references
//
// Code available from: https://verilator.org
//
//*************************************************************************
//
// Copyright 2003-2020 by Wilson Snyder. This program is free software; you
// can redistribute it and/or modify it under the terms of either the GNU
// Lesser General Public License Version 3 or the Perl Artistic License
// Version 2.0.
// SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
//
//*************************************************************************
// Slice TRANSFORMATIONS:
// Top-down traversal (SliceVisitor):
// NODEASSIGN
// ARRAYSEL
// Compare the dimensions to the Var to check for implicit slices.
// Using ->length() calculate the number of clones needed.
// VARREF
// Check the dimensions of the Var for an implicit slice.
// Replace with ArraySel nodes if needed.
// SEL, EXTEND
// We might be assigning a 1-D packed array to a 2-D packed array,
// this is unsupported.
// SliceCloneVisitor (called if this node is a slice):
// NODEASSIGN
// Clone and iterate the clone:
// ARRAYSEL
// Modify bitp() for the new value and set ->length(1)
//
// TODO: This code was written before SLICESEL was a type it might be
// simplified to look primarily for SLICESELs.
//*************************************************************************
#include "config_build.h"
#include "verilatedos.h"
#include "V3Global.h"
#include "V3Slice.h"
#include "V3Ast.h"
//*************************************************************************
class SliceVisitor : public AstNVisitor {
// NODE STATE
// Cleared on netlist
// AstNodeAssign::user1() -> bool. True if find is complete
// AstNodeUniop::user1() -> bool. True if find is complete
// AstArraySel::user1p() -> AstVarRef. The VarRef that the final ArraySel points to
AstUser1InUse m_inuser1;
// STATE
AstNode* m_assignp; // Assignment we are under
bool m_assignError; // True if the current assign already has an error
// METHODS
VL_DEBUG_FUNC; // Declare debug()
AstNode* cloneAndSel(AstNode* nodep, int elements, int offset) {
// Insert an ArraySel, except for a few special cases
AstUnpackArrayDType* arrayp = VN_CAST(nodep->dtypep()->skipRefp(), UnpackArrayDType);
if (!arrayp) { // V3Width should have complained, but...
if (!m_assignError) {
nodep->v3error(
nodep->prettyTypeName()
<< " is not an unpacked array, but is in an unpacked array context");
}
m_assignError = true;
return nodep->cloneTree(false); // Likely will cause downstream errors
}
if (arrayp->rangep()->elementsConst() != elements) {
if (!m_assignError) {
nodep->v3error(
"Slices of arrays in assignments have different unpacked dimensions, "
<< elements << " versus " << arrayp->rangep()->elementsConst());
}
m_assignError = true;
elements = 1;
offset = 0;
}
AstNode* newp;
if (AstInitArray* initp = VN_CAST(nodep, InitArray)) {
UINFO(9, " cloneInitArray(" << elements << "," << offset << ") " << nodep << endl);
int leOffset = !arrayp->rangep()->littleEndian()
? arrayp->rangep()->elementsConst() - 1 - offset
: offset;
AstNode* itemp = initp->getIndexDefaultedValuep(leOffset);
if (!itemp) {
nodep->v3error("Array initialization has too few elements, need element "
<< offset);
itemp = initp->initsp();
}
newp = itemp->cloneTree(false);
} else if (AstNodeCond* snodep = VN_CAST(nodep, NodeCond)) {
UINFO(9, " cloneCond(" << elements << "," << offset << ") " << nodep << endl);
return snodep->cloneType(snodep->condp()->cloneTree(false),
cloneAndSel(snodep->expr1p(), elements, offset),
cloneAndSel(snodep->expr2p(), elements, offset));
} else if (AstSliceSel* snodep = VN_CAST(nodep, SliceSel)) {
UINFO(9, " cloneSliceSel(" << elements << "," << offset << ") " << nodep << endl);
int leOffset = (snodep->declRange().lo()
+ (!snodep->declRange().littleEndian()
? snodep->declRange().elements() - 1 - offset
: offset));
newp = new AstArraySel(nodep->fileline(), snodep->fromp()->cloneTree(false), leOffset);
} else if (VN_IS(nodep, ArraySel) || VN_IS(nodep, NodeVarRef) || VN_IS(nodep, NodeSel)) {
UINFO(9, " cloneSel(" << elements << "," << offset << ") " << nodep << endl);
int leOffset = !arrayp->rangep()->littleEndian()
? arrayp->rangep()->elementsConst() - 1 - offset
: offset;
newp = new AstArraySel(nodep->fileline(), nodep->cloneTree(false), leOffset);
} else {
if (!m_assignError) {
nodep->v3error(nodep->prettyTypeName()
<< " unexpected in assignment to unpacked array");
}
m_assignError = true;
newp = nodep->cloneTree(false); // Likely will cause downstream errors
}
return newp;
}
virtual void visit(AstNodeAssign* nodep) VL_OVERRIDE {
// Called recursively on newly created assignments
if (!nodep->user1() && !VN_IS(nodep, AssignAlias)) {
nodep->user1(true);
m_assignError = false;
if (debug() >= 9) nodep->dumpTree(cout, " Deslice-In: ");
AstNodeDType* dtp = nodep->lhsp()->dtypep()->skipRefp();
if (AstUnpackArrayDType* arrayp = VN_CAST(dtp, UnpackArrayDType)) {
// Left and right could have different msb/lsbs/endianness, but #elements is common
// and all variables are realigned to start at zero
// Assign of a little endian'ed slice to a big endian one must reverse the elements
AstNode* newlistp = NULL;
int elements = arrayp->rangep()->elementsConst();
for (int offset = 0; offset < elements; ++offset) {
AstNode* newp = nodep->cloneType // AstNodeAssign
(cloneAndSel(nodep->lhsp(), elements, offset),
cloneAndSel(nodep->rhsp(), elements, offset));
if (debug() >= 9) { newp->dumpTree(cout, "-new "); }
newlistp = AstNode::addNextNull(newlistp, newp);
}
if (debug() >= 9) nodep->dumpTree(cout, " Deslice-Dn: ");
nodep->replaceWith(newlistp);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
// Normal edit iterator will now iterate on all of the expansion assignments
// This will potentially call this function again to resolve next level of slicing
return;
}
m_assignp = nodep;
iterateChildren(nodep);
m_assignp = NULL;
}
}
virtual void visit(AstInitArray* nodep) VL_OVERRIDE {
UASSERT_OBJ(!m_assignp, nodep, "Array initialization should have been removed earlier");
}
void expandBiOp(AstNodeBiop* nodep) {
if (!nodep->user1()) {
nodep->user1(true);
// If it's an unpacked array, blow it up into comparing each element
AstNodeDType* fromDtp = nodep->lhsp()->dtypep()->skipRefp();
UINFO(9, " Bi-Eq/Neq expansion " << nodep << endl);
if (AstUnpackArrayDType* adtypep = VN_CAST(fromDtp, UnpackArrayDType)) {
AstNodeBiop* logp = NULL;
if (!VN_IS(nodep->lhsp()->dtypep()->skipRefp(), NodeArrayDType)) {
nodep->lhsp()->v3error(
"Slice operator "
<< nodep->lhsp()->prettyTypeName()
<< " on non-slicable (e.g. non-vector) left-hand-side operand");
} else if (!VN_IS(nodep->rhsp()->dtypep()->skipRefp(), NodeArrayDType)) {
nodep->rhsp()->v3error(
"Slice operator "
<< nodep->rhsp()->prettyTypeName()
<< " on non-slicable (e.g. non-vector) right-hand-side operand");
} else {
for (int index = 0; index < adtypep->rangep()->elementsConst(); ++index) {
// EQ(a,b) -> LOGAND(EQ(ARRAYSEL(a,0), ARRAYSEL(b,0)), ...[1])
AstNodeBiop* clonep
= VN_CAST(nodep->cloneType(
new AstArraySel(nodep->fileline(),
nodep->lhsp()->cloneTree(false), index),
new AstArraySel(nodep->fileline(),
nodep->rhsp()->cloneTree(false), index)),
NodeBiop);
if (!logp)
logp = clonep;
else {
switch (nodep->type()) {
case AstType::atEq: // FALLTHRU
case AstType::atEqCase:
logp = new AstLogAnd(nodep->fileline(), logp, clonep);
break;
case AstType::atNeq: // FALLTHRU
case AstType::atNeqCase:
logp = new AstLogOr(nodep->fileline(), logp, clonep);
break;
default:
nodep->v3fatalSrc("Unknown node type processing array slice");
break;
}
}
}
UASSERT_OBJ(logp, nodep, "Unpacked array with empty indices range");
nodep->replaceWith(logp);
VL_DO_DANGLING(pushDeletep(nodep), nodep);
nodep = logp;
}
}
iterateChildren(nodep);
}
}
virtual void visit(AstEq* nodep) VL_OVERRIDE { expandBiOp(nodep); }
virtual void visit(AstNeq* nodep) VL_OVERRIDE { expandBiOp(nodep); }
virtual void visit(AstEqCase* nodep) VL_OVERRIDE { expandBiOp(nodep); }
virtual void visit(AstNeqCase* nodep) VL_OVERRIDE { expandBiOp(nodep); }
virtual void visit(AstNode* nodep) VL_OVERRIDE { iterateChildren(nodep); }
public:
// CONSTRUCTORS
explicit SliceVisitor(AstNetlist* nodep) {
m_assignp = NULL;
m_assignError = false;
iterate(nodep);
}
virtual ~SliceVisitor() {}
};
//######################################################################
// Link class functions
void V3Slice::sliceAll(AstNetlist* nodep) {
UINFO(2, __FUNCTION__ << ": " << endl);
{ SliceVisitor visitor(nodep); } // Destruct before checking
V3Global::dumpCheckGlobalTree("slice", 0, v3Global.opt.dumpTreeLevel(__FILE__) >= 3);
}