CODEWITHSUNDEEP
c++linkerverilator
Jon Taylor
Jon Taylor

Reputation: 301

Why is a c++ method which is defined static in a header file not showing up in a symbol table

I am trying to compile and link the runtime support code for Verilator (veripool.org). It builds fine, but for some reason there are a couple of methods which aren't showing up in the pertinent object file, Verilated::timeunit(int) and Verilated::timeprecision(int).

Those are ostensibly defined in include/verilated.h:

    static int timeunit() VL_MT_SAFE { return Verilated::threadContextp()->timeunit(); }
    static int timeprecision() VL_MT_SAFE { return Verilated::threadContextp()->timeprecision(); }

Now, you can see that there is a parameter to both methods of type int in the calling function which shows up in the linking step:

ld: /home/jon/controlix/src/nuttx/nuttx/staging/libcontrols.a(Vhello_world__ALL.o): in function `Vhello_world::__Vconfigure(Vhello_world__Syms*, bool)':
Vhello_world__ALL.cpp:(.text+0x15): undefined reference to `Verilated::timeunit(int)'
Vhello_world__ALL.cpp:(.text+0x15): relocation truncated to fit: R_X86_64_PLT32 against undefined symbol `Verilated::timeunit(int)'
ld: Vhello_world__ALL.cpp:(.text+0x20): undefined reference to `Verilated::timeprecision(int)'
Vhello_world__ALL.cpp:(.text+0x20): relocation truncated to fit: R_X86_64_PLT32 against undefined symbol `Verilated::timeprecision(int)'
l

I have tried changing the method declarations in verilated.h to take an int as a parameter even though lack of that should cause a compile-time error, but still those two method declarations don't show up in the symbol table for verilated.cpp. Other methods in the Verilated:: class show up just fine.

What am I missing?

Upvotes: 2

Views: 338

Answers (1)

eerorika
eerorika

Reputation: 238361

Why is a c++ method which is defined static in a header file not showing up in a symbol table

Edit: Initially, I assumed that those are non-member functions such as in your quote. Looking at the source, I find that they are member functions. But what I also find is:

#ifndef VL_NO_LEGACY
    // Deprecated
    static int timeunit() VL_MT_SAFE { return Verilated::threadContextp()->timeunit(); }
    static int timeprecision() VL_MT_SAFE { return Verilated::threadContextp()->timeprecision(); }

If the macro VL_NO_LEGACY is defined, then those functions won't be defined nor declared. This would explain the lack of their symbols.

Verilated::timeunit(int) and Verilated::timeprecision(int).

Those are ostensibly defined in include/verilated.h:

static int timeunit() VL_MT_SAFE { return Verilated::threadContextp()->timeunit(); }
static int timeprecision() VL_MT_SAFE { return Verilated::threadContextp()->timeprecision(); }

No, those are definitely not definitions of the functions declared above. Note the different parameter list.

even though lack of that should cause a compile-time error

Not necessarily. The definition of static int timeunit() won't hinder the declaration of Verilated::timeunit(int).

Upvotes: 3

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