AstNode* newSubNeg(AstNode* lhsp, vlsint32_t rhs) {
// Return lhs-rhs, but if rhs is negative use an add, so we won't
// have to deal with signed math and related 32bit sign extension problems
if (rhs == 0) {
return lhsp;
} else if (lhsp->castConst()) {
// Optional vs just making add/sub below, but saves constification some work
V3Number num (lhsp->fileline(), lhsp->width());
num.opSub(lhsp->castConst()->num(), V3Number(lhsp->fileline(), 32, rhs));
num.isSigned(lhsp->isSigned());
AstNode* newp = new AstConst(lhsp->fileline(), num);
return newp;
} else if (rhs > 0) {
AstNode* newp = new AstSub(lhsp->fileline(), lhsp,
new AstConst(lhsp->fileline(), AstConst::Unsized32(), rhs));
// We must make sure sub gets sign of original value, not from the constant
newp->dtypeFrom(lhsp);
return newp;
} else { // rhs < 0;
AstNode* newp = new AstAdd(lhsp->fileline(), lhsp,
new AstConst(lhsp->fileline(), AstConst::Unsized32(), -rhs));
// We must make sure sub gets sign of original value, not from the constant
newp->dtypeFrom(lhsp);
return newp;
}
}
void visitShift (AstNodeBiop* nodep) {
// Shifts of > 32/64 bits in C++ will wrap-around and generate non-0s
if (!nodep->user2SetOnce()) {
UINFO(4," ShiftFix "<<nodep<<endl);
AstConst* shiftp = nodep->rhsp()->castConst();
if (shiftp && shiftp->num().mostSetBitP1() > 32) {
shiftp->v3error("Unsupported: Shifting of by over 32-bit number isn't supported."
<<" (This isn't a shift of 32 bits, but a shift of 2^32, or 4 billion!)\n");
}
if (nodep->widthMin()<=64 // Else we'll use large operators which work right
// C operator's width must be < maximum shift which is based on Verilog width
&& nodep->width() < (1LL<<nodep->rhsp()->widthMin())) {
AstNRelinker replaceHandle;
nodep->unlinkFrBack(&replaceHandle);
AstNode* constzerop;
int m1value = nodep->widthMin()-1; // Constant of width-1; not changing dtype width
if (nodep->signedFlavor()) {
// Then over shifting gives the sign bit, not all zeros
// Note *NOT* clean output -- just like normal shift!
// Create equivalent of VL_SIGNONES_(node_width)
constzerop = new AstNegate (nodep->fileline(),
new AstShiftR(nodep->fileline(),
nodep->lhsp()->cloneTree(false),
new AstConst(nodep->fileline(),
m1value),
nodep->width()));
} else {
V3Number zeronum (nodep->fileline(), nodep->width(), 0);
constzerop = new AstConst(nodep->fileline(), zeronum);
}
constzerop->dtypeFrom (nodep); // unsigned
V3Number widthnum (nodep->fileline(), nodep->rhsp()->widthMin(), m1value);
AstNode* constwidthp = new AstConst(nodep->fileline(), widthnum);
constwidthp->dtypeFrom (nodep->rhsp()); // unsigned
AstCond* newp =
new AstCond (nodep->fileline(),
new AstGte (nodep->fileline(),
constwidthp,
nodep->rhsp()->cloneTree(false)),
nodep,
constzerop);
replaceHandle.relink(newp);
}
}
nodep->iterateChildren(*this); checkNode(nodep);
}
AstNode* newSubNeg(vlsint32_t lhs, AstNode* rhsp) {
// Return lhs-rhs
// We must make sure sub gets sign of original value
AstNode* newp = new AstSub(rhsp->fileline(),
new AstConst(rhsp->fileline(), AstConst::Unsized32(), lhs),
rhsp);
newp->dtypeFrom(rhsp); // Important as AstSub default is lhs's sign
return newp;
}
