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Fix `$bits` on unpacked structs (#4521) (#7796) 

Fixes #4521.
This commit is contained in:
Nick Brereton 2026-06-17 17:56:48 -04:00 committed by GitHub
parent 4c5e104825
commit 26c85d4495
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GPG Key ID: B5690EEEBB952194
5 changed files with 94 additions and 2 deletions
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50
src/V3LinkDot.cpp
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@ -1993,6 +1993,17 @@ class LinkDotFindVisitor final : public VNVisitor {
// No need to insert, only the real typedef matters, but need to track for errors
nodep->user1p(m_curSymp);
}
void visit(AstNodeUOrStructDType* nodep) override { // FindVisitor::
UASSERT_OBJ(m_curSymp, nodep, "Struct/union dtype not under module/package/$unit");
VL_RESTORER(m_curSymp);
m_curSymp = m_statep->insertBlock(m_curSymp, "__Vdtype" + cvtToStr(nodep->uniqueNum()),
nodep, m_classOrPackagep);
iterateChildren(nodep);
}
void visit(AstMemberDType* nodep) override { // FindVisitor::
iterateChildren(nodep);
m_statep->insertSym(m_curSymp, nodep->name(), nodep, m_classOrPackagep);
}
void visit(AstParamTypeDType* nodep) override { // FindVisitor::
UASSERT_OBJ(m_curSymp, nodep, "Parameter type not under module/package/$unit");
@ -3511,6 +3522,20 @@ class LinkDotResolveVisitor final : public VNVisitor {
<< declp->warnContextSecondary());
}
}
void checkMemberDeclOrder(AstNode* nodep, AstMemberDType* declp) {
const uint32_t declTokenNum = declp->fileline()->tokenNum();
if (nodep->fileline()->tokenNum() < declTokenNum) {
UINFO(1, "Related node " << nodep->fileline()->tokenNum() << " " << nodep);
UINFO(1, "Related decl " << declTokenNum << " " << declp);
nodep->v3error("Reference to "
<< nodep->prettyNameQ() << " before declaration (IEEE 1800-2023 6.18)\n"
<< nodep->warnMore()
<< "... Suggest move the declaration before the reference\n"
<< nodep->warnContextPrimary() << '\n'
<< declp->warnOther() << "... Location of original declaration\n"
<< declp->warnContextSecondary());
}
}
void replaceWithCheckBreak(AstNode* oldp, AstNodeDType* newp) {
// Flag now to avoid V3Broken throwing an internal error
@ -3536,6 +3561,15 @@ class LinkDotResolveVisitor final : public VNVisitor {
if (nodep && nodep->isParam()) nodep->usedParam(true);
}
static VSymEnt* findIdFallbackSkipMemberDType(VSymEnt* lookp, const string& name) {
while (lookp) {
VSymEnt* const foundp = lookp->findIdFlat(name);
if (foundp && !VN_IS(foundp->nodep(), MemberDType)) return foundp;
lookp = lookp->fallbackp();
}
return nullptr;
}
void symIterateChildren(AstNode* nodep, VSymEnt* symp) {
// Iterate children, changing to given context, with restore to old context
VL_RESTORER(m_ds);
@ -4532,6 +4566,16 @@ class LinkDotResolveVisitor final : public VNVisitor {
} else {
(void)defp; // Prevent unused variable warning
}
} else if (AstMemberDType* const defp = VN_CAST(foundp->nodep(), MemberDType)) {
if (allowVar) {
checkMemberDeclOrder(nodep, defp);
AstRefDType* const refp = new AstRefDType{nodep->fileline(), nodep->name()};
refp->refDTypep(defp);
replaceWithCheckBreak(nodep, refp);
VL_DO_DANGLING(pushDeletep(nodep), nodep);
ok = true;
m_ds.m_dotText = "";
}
} else if (AstEnumItem* const valuep = VN_CAST(foundp->nodep(), EnumItem)) {
if (allowVar) {
AstNode* const newp
@ -4967,6 +5011,10 @@ class LinkDotResolveVisitor final : public VNVisitor {
refdtypep->v3error("Self-referential enumerated type definition");
}
}
void visit(AstNodeUOrStructDType* nodep) override {
LINKDOT_VISIT_START();
symIterateChildren(nodep, m_statep->getNodeSym(nodep));
}
void visit(AstEnumItemRef* nodep) override {
// Resolve its reference
// EnumItemRefs are created by the first pass, but V3Param may regenerate due to
@ -5984,7 +6032,7 @@ class LinkDotResolveVisitor final : public VNVisitor {
if (nodep->classOrPackagep()) {
foundp = m_statep->getNodeSym(nodep->classOrPackagep())->findIdFlat(nodep->name());
} else if (m_ds.m_dotPos == DP_FIRST || m_ds.m_dotPos == DP_NONE) {
foundp = m_curSymp->findIdFallback(nodep->name());
foundp = findIdFallbackSkipMemberDType(m_curSymp, nodep->name());
} else {
// Defensive: dotPos should be DP_FIRST/DP_NONE or classOrPackagep set.
v3fatalSrc("Unexpected dotPos="

3
src/V3Width.cpp
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@ -9661,7 +9661,8 @@ class WidthVisitor final : public VNVisitor {
continue;
} else if (const AstNodeUOrStructDType* const adtypep
= VN_CAST(dtypep, NodeUOrStructDType)) {
bits *= adtypep->width();
bits *= adtypep->isStreamableFixedAggregate() ? adtypep->widthStream()
: adtypep->width();
break;
} else if (const AstBasicDType* const adtypep = VN_CAST(dtypep, BasicDType)) {
bits *= adtypep->width();

30
test_regress/t/t_stream_unpacked_struct.v
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@ -83,6 +83,17 @@ module t;
byte tail;
} packed_union_struct_t;
localparam int WORD_WIDTH = 16;
typedef union packed {
struct packed {
logic [15:0] temp_1;
logic [15:0] temp_2;
logic [15:0] temp_3;
} regs;
logic [($bits(regs) / WORD_WIDTH)-1:0][WORD_WIDTH-1:0] words;
} issue_4521_union_t;
simple_t simple;
simple_t simple_out;
simple_t simple_cont_out;
@ -106,6 +117,7 @@ module t;
real_struct_t real_struct_out;
packed_union_struct_t packed_union_struct;
packed_union_struct_t packed_union_struct_out;
issue_4521_union_t issue_4521_union;
logic [19:0] simple_bits;
logic [31:0] wide_simple_bits;
@ -122,6 +134,7 @@ module t;
logic [15:0] packed_union_bits;
logic [11:0] narrow_bits;
logic [19:0] simple_streaml_src;
logic [$bits(simple_t)-1:0] simple_bits_from_bits;
byte byte_array_out[2];
assign {>>{simple_cont_out}} = 20'habcde;
@ -138,6 +151,13 @@ module t;
`checkh(simple_bits, 20'h54321);
simple = '{8'h12, 4'ha, '{4'hb, 4'hc}};
`checkh($bits(simple_t), 20);
`checkh($bits(array_t), 32);
`checkh($bits(nested_t), 36);
`checkh($bits(struct_array_t), 56);
`checkh($bits(simple_array), 40);
simple_bits_from_bits = {>>{simple}};
`checkh(simple_bits_from_bits, 20'h12abc);
simple_bits = {>>{simple}};
`checkh(simple_bits, 20'h12abc);
/* verilator lint_off WIDTHEXPAND */
@ -341,6 +361,16 @@ module t;
`checkh(packed_union_struct_out.u.byte_data, 8'hca);
`checkh(packed_union_struct_out.tail, 8'hfe);
`checkh($bits(issue_4521_union_t), 48);
`checkh($bits(issue_4521_union.regs), 48);
`checkh($bits(issue_4521_union.words), 48);
issue_4521_union.regs.temp_1 = 16'h1234;
issue_4521_union.regs.temp_2 = 16'h5678;
issue_4521_union.regs.temp_3 = 16'h9abc;
`checkh(issue_4521_union.words[2], 16'h1234);
`checkh(issue_4521_union.words[1], 16'h5678);
`checkh(issue_4521_union.words[0], 16'h9abc);
$write("*-* All Finished *-*\n");
$finish;
end

7
test_regress/t/t_struct_type_bad.out
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@ -2,4 +2,11 @@
13 | i badi;
| ^
... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.
%Error: t/t_struct_type_bad.v:18:19: Reference to 'later' before declaration (IEEE 1800-2023 6.18)
: ... Suggest move the declaration before the reference
18 | logic [($bits(later) / 8)-1:0][7:0] bad_forward;
| ^~~~~
t/t_struct_type_bad.v:19:18: ... Location of original declaration
19 | logic [15:0] later;
| ^~~~~
%Error: Exiting due to

6
test_regress/t/t_struct_type_bad.v
View File

@ -13,4 +13,10 @@ module t;
i badi; // Bad
} struct_t;
typedef union packed {
// Bad
logic [($bits(later) / 8)-1:0][7:0] bad_forward;
logic [15:0] later;
} forward_member_t;
endmodule