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Report UNUSED on parameters, localparam and genvars (#2627).

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This commit is contained in:
Wilson Snyder 2020-12-07 19:49:50 -05:00
parent 251812638d
commit 47eeef485d
11 changed files with 67 additions and 39 deletions
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4
Changes
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@ -5,10 +5,14 @@ The contributors that suggested a given feature are shown in []. Thanks!
* Verilator 4.107 devel
** Support randomize() class method and rand (#2607). [Krzysztof Bieganski]
*** Support $cast and new CASTCONST warning.
*** Add --top option as alias of --top-module.
**** Report UNUSED on parameters, localparam and genvars (#2627). [Charles Eric LaForest]
**** Fix passing parameter type instantiations by position number.

8
bin/verilator
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@ -4973,10 +4973,10 @@ design simulate incorrectly; see the details under --bbox-unsup.
=item UNUSED
Warns that the specified signal is never used/consumed. Verilator is
fairly liberal in the usage calculations; making a signal public, a signal
matching --unused-regexp ("*unused*") or accessing only a single array
element marks the entire signal as used.
Warns that the specified signal or parameter is never used/consumed.
Verilator is fairly liberal in the usage calculations; making a signal
public, a signal matching --unused-regexp ("*unused*") or accessing only a
single array element marks the entire signal as used.
Disabled by default as this is a code style warning; it will simulate
correctly.

6
src/V3Dead.cpp
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@ -330,12 +330,6 @@ private:
if (nodep->isSigPublic()) return false; // Can't elim publics!
if (nodep->isIO() || nodep->isClassMember()) return false;
if (nodep->isTemp() && !nodep->isTrace()) return true;
if (nodep->isParam()) {
const bool overriddenForHierBlock
= m_modp && m_modp->hierBlock() && nodep->overriddenParam();
if (!nodep->isTrace() && !overriddenForHierBlock && !v3Global.opt.xmlOnly())
return true;
}
return m_elimUserVars; // Post-Trace can kill most anything
}

2
src/V3LinkResolve.cpp
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@ -105,7 +105,7 @@ private:
virtual void visit(AstNodeVarRef* nodep) override {
// VarRef: Resolve its reference
if (nodep->varp()) { nodep->varp()->usedParam(true); }
if (nodep->varp()) nodep->varp()->usedParam(true);
iterateChildren(nodep);
}

30
src/V3Undriven.cpp
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@ -149,7 +149,7 @@ public:
void reportViolations() {
// Combine bits into overall state
AstVar* nodep = m_varp;
if (!nodep->isParam() && !nodep->isGenVar()) {
{
bool allU = true;
bool allD = true;
bool anyU = m_wholeFlags[FLAG_USED];
@ -168,8 +168,12 @@ public:
anyDnotU |= !used && driv;
anynotDU |= !used && !driv;
}
if ((nodep->isGenVar() || nodep->isParam()) && nodep->isUsedParam())
allD = allU = true;
if (allU) m_wholeFlags[FLAG_USED] = true;
if (allD) m_wholeFlags[FLAG_DRIVEN] = true;
const char* const what
= nodep->isParam() ? "parameter" : nodep->isGenVar() ? "genvar" : "signal";
// Test results
if (nodep->isIfaceRef()) {
// For interface top level we don't do any tracking
@ -181,35 +185,39 @@ public:
// UNDRIVEN is considered more serious - as is more likely a bug,
// thus undriven+unused bits get UNUSED warnings, as they're not as buggy.
if (!unusedMatch(nodep)) {
nodep->v3warn(UNUSED,
"Signal is not driven, nor used: " << nodep->prettyNameQ());
nodep->v3warn(UNUSED, ucfirst(what) << " is not driven, nor used: "
<< nodep->prettyNameQ());
nodep->fileline()->modifyWarnOff(V3ErrorCode::UNUSED, true); // Warn only once
}
} else if (allD && !anyU) {
if (!unusedMatch(nodep)) {
nodep->v3warn(UNUSED, "Signal is not used: " << nodep->prettyNameQ());
nodep->v3warn(UNUSED, ucfirst(what)
<< " is not used: " << nodep->prettyNameQ());
nodep->fileline()->modifyWarnOff(V3ErrorCode::UNUSED, true); // Warn only once
}
} else if (!anyD && allU) {
nodep->v3warn(UNDRIVEN, "Signal is not driven: " << nodep->prettyNameQ());
nodep->v3warn(UNDRIVEN, ucfirst(what)
<< " is not driven: " << nodep->prettyNameQ());
nodep->fileline()->modifyWarnOff(V3ErrorCode::UNDRIVEN, true); // Warn only once
} else {
// Bits have different dispositions
bool setU = false;
bool setD = false;
if (anynotDU && !unusedMatch(nodep)) {
nodep->v3warn(UNUSED, "Bits of signal are not driven, nor used: "
<< nodep->prettyNameQ() << bitNames(BN_BOTH));
nodep->v3warn(UNUSED, "Bits of " << what << " are not driven, nor used: "
<< nodep->prettyNameQ() << bitNames(BN_BOTH));
setU = true;
}
if (anyDnotU && !unusedMatch(nodep)) {
nodep->v3warn(UNUSED, "Bits of signal are not used: " << nodep->prettyNameQ()
<< bitNames(BN_UNUSED));
nodep->v3warn(UNUSED, "Bits of " << what
<< " are not used: " << nodep->prettyNameQ()
<< bitNames(BN_UNUSED));
setU = true;
}
if (anyUnotD) {
nodep->v3warn(UNDRIVEN, "Bits of signal are not driven: "
<< nodep->prettyNameQ() << bitNames(BN_UNDRIVEN));
nodep->v3warn(UNDRIVEN,
"Bits of " << what << " are not driven: " << nodep->prettyNameQ()
<< bitNames(BN_UNDRIVEN));
setD = true;
}
if (setU) { // Warn only once

1
test_regress/t/t_delay.v
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@ -8,7 +8,6 @@ module t (/*AUTOARG*/
// Inputs
clk
);
parameter PAR = 3;
input clk;
integer cyc=1;

28
test_regress/t/t_delay_stmtdly_bad.out
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@ -1,26 +1,26 @@
%Warning-ASSIGNDLY: t/t_delay.v:23:13: Unsupported: Ignoring delay on this assignment/primitive.
23 | assign #(1.2000000000000000) dly1 = dly0 + 32'h1;
%Warning-ASSIGNDLY: t/t_delay.v:22:13: Unsupported: Ignoring delay on this assignment/primitive.
22 | assign #(1.2000000000000000) dly1 = dly0 + 32'h1;
| ^~~~~~~~~~~~~~~~~~
... Use "/* verilator lint_off ASSIGNDLY */" and lint_on around source to disable this message.
%Warning-ASSIGNDLY: t/t_delay.v:28:19: Unsupported: Ignoring delay on this assignment/primitive.
28 | dly0 <= #0 32'h11;
%Warning-ASSIGNDLY: t/t_delay.v:27:19: Unsupported: Ignoring delay on this assignment/primitive.
27 | dly0 <= #0 32'h11;
| ^
%Warning-ASSIGNDLY: t/t_delay.v:31:19: Unsupported: Ignoring delay on this assignment/primitive.
31 | dly0 <= #0.12 dly0 + 32'h12;
%Warning-ASSIGNDLY: t/t_delay.v:30:19: Unsupported: Ignoring delay on this assignment/primitive.
30 | dly0 <= #0.12 dly0 + 32'h12;
| ^~~~
%Warning-ASSIGNDLY: t/t_delay.v:39:25: Unsupported: Ignoring delay on this assignment/primitive.
39 | dly0 <= #(dly_s.dly) 32'h55;
%Warning-ASSIGNDLY: t/t_delay.v:38:25: Unsupported: Ignoring delay on this assignment/primitive.
38 | dly0 <= #(dly_s.dly) 32'h55;
| ^
%Warning-STMTDLY: t/t_delay.v:44:11: Unsupported: Ignoring delay on this delayed statement.
%Warning-STMTDLY: t/t_delay.v:43:11: Unsupported: Ignoring delay on this delayed statement.
: ... In instance t
44 | #100 $finish;
43 | #100 $finish;
| ^~~
%Warning-UNUSED: t/t_delay.v:21:12: Signal is not used: 'dly_s'
%Warning-UNUSED: t/t_delay.v:20:12: Signal is not used: 'dly_s'
: ... In instance t
21 | dly_s_t dly_s;
20 | dly_s_t dly_s;
| ^~~~~
%Warning-BLKSEQ: t/t_delay.v:38:20: Blocking assignments (=) in sequential (flop or latch) block
%Warning-BLKSEQ: t/t_delay.v:37:20: Blocking assignments (=) in sequential (flop or latch) block
: ... Suggest delayed assignments (<=)
38 | dly_s.dly = 55;
37 | dly_s.dly = 55;
| ^
%Error: Exiting due to

1
test_regress/t/t_lint_defparam.v
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@ -13,4 +13,5 @@ endmodule
module sub;
parameter P = 6;
if (P != 0) ; // Prevent unused
endmodule

2
test_regress/t/t_lint_unused.v
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@ -44,8 +44,6 @@ module sub;
wire pub /*verilator public*/; // Ignore publics
localparam THREE = 3;
endmodule
primitive udp_mux2 (q, a, b, s);

12
test_regress/t/t_lint_unused_bad.out
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@ -23,4 +23,16 @@
: ... In instance t.sub
28 | wire [3:0] mixed;
| ^~~~~
%Warning-UNUSED: t/t_lint_unused_bad.v:37:14: Parameter is not used: 'UNUSED_P'
: ... In instance t.sub
37 | parameter UNUSED_P = 1;
| ^~~~~~~~
%Warning-UNUSED: t/t_lint_unused_bad.v:38:15: Parameter is not used: 'UNUSED_LP'
: ... In instance t.sub
38 | localparam UNUSED_LP = 2;
| ^~~~~~~~~
%Warning-UNUSED: t/t_lint_unused_bad.v:40:15: Genvar is not driven, nor used: 'unused_gv'
: ... In instance t.sub
40 | genvar unused_gv;
| ^~~~~~~~~
%Error: Exiting due to

12
test_regress/t/t_lint_unused_bad.v
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@ -34,9 +34,21 @@ module sub;
localparam THREE = 3;
parameter UNUSED_P = 1;
localparam UNUSED_LP = 2;
genvar unused_gv;
genvar ok_gv;
initial begin
if (0 && assunu1[0] != 0 && udrb2 != 0) begin end
if (0 && assunub2[THREE] && assunub2[1:0]!=0) begin end
if (0 && mixed[1:0] != 0) begin end
end
generate
if (0)
for (ok_gv = 0; ok_gv < 1; ++ok_gv) begin end
endgenerate
endmodule