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Internals: Prep for #2597. No functional change intended

This commit is contained in:
Wilson Snyder 2020-11-08 18:58:31 -05:00
parent 9655e287ab
commit 6e7b07c794
1 changed files with 37 additions and 33 deletions
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70
src/V3Width.cpp
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@ -1709,39 +1709,7 @@ private:
width = 1; width = 1;
} }
userIterateAndNext(nodep->lhsp(), WidthVP(SELF, PRELIM).p()); userIterateAndNext(nodep->lhsp(), WidthVP(SELF, PRELIM).p());
AstBasicDType* underDtp = VN_CAST(nodep->lhsp()->dtypep(), BasicDType); castSized(nodep, nodep->lhsp(), width); // lhsp may change
if (!underDtp) underDtp = nodep->lhsp()->dtypep()->basicp();
if (!underDtp) {
nodep->v3warn(E_UNSUPPORTED,
"Unsupported: Size-changing cast on non-basic data type");
underDtp = VN_CAST(nodep->findLogicBoolDType(), BasicDType);
}
// A cast propagates its size to the lower expression and is included in the maximum
// width, so 23'(1'b1 + 1'b1) uses 23-bit math, but 1'(2'h2 * 2'h1) uses two-bit math.
// However the output width is exactly that requested.
// So two steps, first do the calculation's width (max of the two widths)
{
int calcWidth = std::max(width, underDtp->width());
AstNodeDType* calcDtp
= (underDtp->isFourstate()
? nodep->findLogicDType(calcWidth, calcWidth, underDtp->numeric())
: nodep->findBitDType(calcWidth, calcWidth, underDtp->numeric()));
nodep->dtypep(calcDtp);
// We ignore warnings as that is sort of the point of a cast
iterateCheck(nodep, "Cast expr", nodep->lhsp(), CONTEXT, FINAL, calcDtp,
EXTEND_EXP, false);
}
// if (debug()) nodep->dumpTree(cout, " CastSizeClc: ");
// Next step, make the proper output width
{
AstNodeDType* outDtp
= (underDtp->isFourstate()
? nodep->findLogicDType(width, width, underDtp->numeric())
: nodep->findBitDType(width, width, underDtp->numeric()));
nodep->dtypep(outDtp);
// We ignore warnings as that is sort of the point of a cast
widthCheckSized(nodep, "Cast expr", nodep->lhsp(), outDtp, EXTEND_EXP, false);
}
} }
if (m_vup->final()) { if (m_vup->final()) {
// CastSize not needed once sizes determined // CastSize not needed once sizes determined
@ -1751,6 +1719,42 @@ private:
} }
// if (debug()) nodep->dumpTree(cout, " CastSizeOut: "); // if (debug()) nodep->dumpTree(cout, " CastSizeOut: ");
} }
void castSized(AstNode* nodep, AstNode* underp, int width) {
AstBasicDType* underDtp = VN_CAST(underp->dtypep(), BasicDType);
if (!underDtp) underDtp = underp->dtypep()->basicp();
if (!underDtp) {
nodep->v3warn(E_UNSUPPORTED, "Unsupported: Size-changing cast on non-basic data type");
underDtp = VN_CAST(nodep->findLogicBoolDType(), BasicDType);
}
UASSERT_OBJ(underp == nodep->op1p(), nodep, "Assuming op1 is cast value");
// A cast propagates its size to the lower expression and is included in the maximum
// width, so 23'(1'b1 + 1'b1) uses 23-bit math, but 1'(2'h2 * 2'h1) uses two-bit math.
// However the output width is exactly that requested.
// So two steps, first do the calculation's width (max of the two widths)
{
int calcWidth = std::max(width, underDtp->width());
AstNodeDType* calcDtp
= (underDtp->isFourstate()
? nodep->findLogicDType(calcWidth, calcWidth, underDtp->numeric())
: nodep->findBitDType(calcWidth, calcWidth, underDtp->numeric()));
nodep->dtypep(calcDtp);
// We ignore warnings as that is sort of the point of a cast
iterateCheck(nodep, "Cast expr", underp, CONTEXT, FINAL, calcDtp, EXTEND_EXP, false);
VL_DANGLING(underp);
underp = nodep->op1p(); // Above asserts that op1 was underp pre-relink
}
// if (debug()) nodep->dumpTree(cout, " CastSizeClc: ");
// Next step, make the proper output width
{
AstNodeDType* outDtp = (underDtp->isFourstate()
? nodep->findLogicDType(width, width, underDtp->numeric())
: nodep->findBitDType(width, width, underDtp->numeric()));
nodep->dtypep(outDtp);
// We ignore warnings as that is sort of the point of a cast
widthCheckSized(nodep, "Cast expr", underp, outDtp, EXTEND_EXP, false);
VL_DANGLING(underp);
}
}
virtual void visit(AstVar* nodep) override { virtual void visit(AstVar* nodep) override {
// if (debug()) nodep->dumpTree(cout, " InitPre: "); // if (debug()) nodep->dumpTree(cout, " InitPre: ");
// Must have deterministic constant width // Must have deterministic constant width