CODEWITHSUNDEEP
gcccygwingprof
netawater
netawater

Reputation: 15844

how to pass -pg to gcc in cygwin

I just want to test -pg, the source file is very simple, my environment is cygwin, 

$ uname -a 
CYGWIN_NT-10.0 SHA-LPLATOW 2.8.2(0.313/5/3) 2017-07-12 10:58 x86_64 Cygwin

$ vi pgtest.c

#include <stdio.h>
void main(void){
    printf("hello, world\n");        
}

no -pg compiling is OK.

$ gcc -c pgtest.c
$ gcc -o pgtest.exe pgtest.o

but -pg report error

$ gcc -pg -c pgtest.c
$ gcc -o pgtest.exe pgtest.o
pgtest.o:pgtest.c:(.text+0x1): undefined reference to `__fentry__'
pgtest.o:pgtest.c:(.text+0x1): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `__fentry__'
pgtest.o:pgtest.c:(.text+0xe): undefined reference to `_monstartup'
pgtest.o:pgtest.c:(.text+0xe): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `_monstartup'
collect2: error: ld returned 1 exit status

I have tried LDFLAGS, it is the same. 

export LDFLAGS="-pg" ; gcc -o pgtest.exe pgtest.o

Upvotes: 3

Views: 1129

Answers (1)

matzeri
matzeri

Reputation: 8466

from the gcc info page

'-pg'
Generate extra code to write profile information suitable for the analysis program 'gprof'. You must use this option when compiling the source files you want data about, and you must also use it when linking.

so if you want to do a separate compilation and linking you need to repeate the -pg

$ gcc -c pgtest.c -pg
$ gcc -o pgtest.exe pgtest.o -pg

Upvotes: 4

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