luke/verilator
1
0
Fork 0
mirror of https://github.com/verilator/verilator.git synced 2026-08-31 18:14:33 +02:00
Code Issues Packages Projects Releases Wiki Activity

Support System Functions in Constraint Blocks (#7028) (#7036)

Browse Source
This commit is contained in:
Yilou Wang
2026-02-11 05:19:25 -08:00
committed by GitHub
parent 5d12ae3a2f
commit 84350859e0
8 changed files with 336 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/V3Randomize.cpp
+162 -9
View File
@@ -1143,15 +1143,15 @@ class ConstraintExprVisitor final : public VNVisitor {
if (isGlobalConstrained && !nodep->backp()) VL_DO_DANGLING(pushDeletep(nodep), nodep);
}
}
void visit(AstCountOnes* nodep) override {
// Convert it to (x & 1) + ((x & 2) >> 1) + ((x & 4) >> 2) + ...
FileLine* const fl = nodep->fileline();
AstNodeExpr* const argp = nodep->lhsp()->unlinkFrBack();
V3Number numOne{nodep, argp->width(), 1};
// Build popcount expansion: (x & 1) + ((x & 2) >> 1) + ...
// argp is consumed; caller must clone if reusing.
AstNodeExpr* buildCountOnesExpansion(FileLine* fl, AstNodeExpr* argp,
AstNodeExpr* dtypeNodep) {
V3Number numOne{fl, argp->width(), 1};
AstNodeExpr* sump = new AstAnd{fl, argp, new AstConst{fl, numOne}};
sump->user1(true);
for (int i = 1; i < argp->width(); i++) {
V3Number numBitMask{nodep, argp->width(), 0};
V3Number numBitMask{fl, argp->width(), 0};
numBitMask.setBit(i, 1);
AstAnd* const andp
= new AstAnd{fl, argp->cloneTreePure(false), new AstConst{fl, numBitMask}};
@@ -1159,11 +1159,17 @@ class ConstraintExprVisitor final : public VNVisitor {
AstShiftR* const shiftp = new AstShiftR{
fl, andp, new AstConst{fl, AstConst::WidthedValue{}, argp->width(), (uint32_t)i}};
shiftp->user1(true);
shiftp->dtypeFrom(nodep);
sump = new AstAdd{nodep->fileline(), sump, shiftp};
shiftp->dtypeFrom(dtypeNodep);
sump = new AstAdd{fl, sump, shiftp};
sump->user1(true);
}
// Restore the original width
return sump;
}
void visit(AstCountOnes* nodep) override {
FileLine* const fl = nodep->fileline();
AstNodeExpr* const argp = nodep->lhsp()->unlinkFrBack();
AstNodeExpr* sump = buildCountOnesExpansion(fl, argp, nodep);
if (nodep->width() > sump->width()) {
sump = new AstExtend{fl, sump, nodep->width()};
sump->user1(true);
@@ -1187,6 +1193,153 @@ class ConstraintExprVisitor final : public VNVisitor {
VL_DO_DANGLING(nodep->deleteTree(), nodep);
iterate(neqp);
}
void visit(AstOneHot* nodep) override {
if (editFormat(nodep)) return;
// $onehot(x) = (x != 0) && ((x & (x-1)) == 0)
FileLine* const fl = nodep->fileline();
AstNodeExpr* const argp = nodep->lhsp()->unlinkFrBack();
const int w = argp->width();
V3Number numZero{fl, w, 0};
AstNeq* const neZerop
= new AstNeq{fl, argp->cloneTreePure(false), new AstConst{fl, numZero}};
neZerop->user1(true);
V3Number numOne{fl, w, 1};
AstSub* const subp = new AstSub{fl, argp->cloneTreePure(false), new AstConst{fl, numOne}};
subp->dtypeFrom(argp);
subp->user1(true);
AstAnd* const andp = new AstAnd{fl, argp, subp};
andp->dtypeFrom(argp);
andp->user1(true);
V3Number numZero2{fl, w, 0};
AstEq* const eqZerop = new AstEq{fl, andp, new AstConst{fl, numZero2}};
eqZerop->user1(true);
AstLogAnd* const resultp = new AstLogAnd{fl, neZerop, eqZerop};
resultp->user1(true);
nodep->replaceWith(resultp);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
iterate(resultp);
}
void visit(AstOneHot0* nodep) override {
if (editFormat(nodep)) return;
// $onehot0(x) = (x & (x-1)) == 0
FileLine* const fl = nodep->fileline();
AstNodeExpr* const argp = nodep->lhsp()->unlinkFrBack();
const int w = argp->width();
V3Number numOne{fl, w, 1};
AstSub* const subp = new AstSub{fl, argp->cloneTreePure(false), new AstConst{fl, numOne}};
subp->dtypeFrom(argp);
subp->user1(true);
AstAnd* const andp = new AstAnd{fl, argp, subp};
andp->dtypeFrom(argp);
andp->user1(true);
V3Number numZero{fl, w, 0};
AstEq* const eqp = new AstEq{fl, andp, new AstConst{fl, numZero}};
eqp->user1(true);
nodep->replaceWith(eqp);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
iterate(eqp);
}
void visit(AstCountBits* nodep) override {
if (editFormat(nodep)) return;
FileLine* const fl = nodep->fileline();
bool countOnes = false;
bool countZeros = false;
for (AstNodeExpr* ctrlp : {nodep->rhsp(), nodep->thsp(), nodep->fhsp()}) {
const AstConst* const cp = VN_CAST(ctrlp, Const);
if (!cp) {
nodep->v3warn(E_UNSUPPORTED,
"Unsupported: non-constant control in $countbits inside constraint");
AstConst* const zerop
= new AstConst{fl, AstConst::WidthedValue{}, nodep->width(), 0u};
nodep->replaceWith(zerop);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
return;
}
if (cp->num().bitIs1(0) && !countOnes)
countOnes = true;
else if (cp->num().bitIs0(0) && !countZeros)
countZeros = true;
}
AstNodeExpr* const argp = nodep->lhsp()->unlinkFrBack();
const int argWidth = argp->width();
AstNodeExpr* sump = nullptr;
if (countOnes && countZeros) {
// ones + zeros = width for 2-state types
sump = new AstConst{fl, AstConst::WidthedValue{}, nodep->width(), (uint32_t)argWidth};
VL_DO_DANGLING(argp->deleteTree(), argp);
} else if (countOnes) {
sump = buildCountOnesExpansion(fl, argp, nodep);
} else if (countZeros) {
// width - countones(x)
AstNodeExpr* const onesCountp = buildCountOnesExpansion(fl, argp, nodep);
V3Number widthVal{nodep, onesCountp->width(), (uint32_t)argWidth};
sump = new AstSub{fl, new AstConst{fl, widthVal}, onesCountp};
sump->dtypeFrom(onesCountp);
sump->user1(true);
} else {
sump = new AstConst{fl, AstConst::WidthedValue{}, nodep->width(), 0u};
VL_DO_DANGLING(argp->deleteTree(), argp);
}
if (nodep->width() > sump->width()) {
sump = new AstExtend{fl, sump, nodep->width()};
sump->user1(true);
} else if (nodep->width() < sump->width()) {
sump = new AstSel{fl, sump, 0, nodep->width()};
sump->user1(true);
}
nodep->replaceWith(sump);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
iterate(sump);
}
void visit(AstCLog2* nodep) override {
if (editFormat(nodep)) return;
// $clog2(x): ITE chain (x<=1)?0 : (x<=2)?1 : ... : argWidth
FileLine* const fl = nodep->fileline();
AstNodeExpr* const argp = nodep->lhsp()->unlinkFrBack();
const int argWidth = argp->width();
const int resultWidth = nodep->width();
AstNodeExpr* resultp
= new AstConst{fl, AstConst::WidthedValue{}, resultWidth, (uint32_t)argWidth};
for (int k = argWidth - 1; k >= 0; k--) {
V3Number threshold{fl, argWidth, 0};
if (k < 32)
threshold.setLong(1ULL << k);
else
threshold.setBit(k, 1);
AstLte* const ltep
= new AstLte{fl, argp->cloneTreePure(false), new AstConst{fl, threshold}};
ltep->user1(true);
AstConst* const valuep
= new AstConst{fl, AstConst::WidthedValue{}, resultWidth, (uint32_t)k};
resultp = new AstCond{fl, ltep, valuep, resultp};
resultp->dtypeChgWidthSigned(resultWidth, resultWidth, VSigning::SIGNED);
resultp->user1(true);
}
VL_DO_DANGLING(argp->deleteTree(), argp);
nodep->replaceWith(resultp);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
iterate(resultp);
}
void visit(AstNodeBiop* nodep) override {
if (editFormat(nodep)) return;
editSMT(nodep, nodep->lhsp(), nodep->rhsp());