external/cde
1
0
Fork 0
mirror of git://git.code.sf.net/p/cdesktopenv/code synced 2025-03-09 15:50:02 +00:00
Code Issues Releases Wiki Activity

Introduce usage of __builtin_unreachable() and noreturn (#248)

Browse source 
This commit adds an UNREACHABLE() macro that expands to either the
__builtin_unreachable() compiler builtin (for release builds) or
abort(3) (for development builds). This is used to mark code paths
that are never to be reached.

It also adds the 'noreturn' attribute to functions that never
return: path_exec(), sh_done() and sh_syntax(). The UNREACHABLE()
macro is not added after calling these.

The purpose of these is:
* to slightly improve GCC/Clang compiler optimizations;
* to fix a few compiler warnings;
* to add code clarity.

Changes of note:

src/cmd/ksh93/sh/io.c: outexcept():
- Avoid using __builtin_unreachable() here since errormsg can
  return despite using ERROR_system(1), as shp->jmplist->mode is
  temporarily set to 0. See: https://github.com/att/ast/issues/1336

src/cmd/ksh93/tests/io.sh:
- Add a regression test for the ksh2020 bug referenced above.

src/lib/libast/features/common:
- Detect the existence of either the C11 stdnoreturn.h header or
  the GCC noreturn attribute, preferring the former when available.
- Test for the existence of __builtin_unreachable(). Use it for
  release builds. On development builds, use abort() instead, which
  crahses reliably for debugging when unreachable code is reached.

Co-authored-by: Martijn Dekker <martijn@inlv.org>
This commit is contained in:
Johnothan King 2021-04-04 16:28:24 -07:00 • committed by GitHub
parent 56913f8c2a
commit c4f980eb29
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
87 changed files with 1170 additions and 122 deletions
Download patch file Download diff file Expand all files Collapse all files

36
src/cmd/ksh93/sh/xec.c
View file

@ -133,7 +133,10 @@ static void get_cpu_times(Shell_t *shp, struct timeval *tv_usr, struct timeval *
double dtime;
if(times(&cpu_times) == (clock_t)-1)
{
errormsg(SH_DICT, ERROR_exit(1), "times(3) failed: %s", strerror(errno));
UNREACHABLE();
}
dtime = (double)cpu_times.tms_utime / shp->gd->lim.clk_tck;
tv1.tv_sec = dtime / 60;
@ -1307,8 +1310,11 @@ int sh_exec(register const Shnode_t *t, int flags)
if(!com[1])
type = 2;
else
{
errormsg(SH_DICT, ERROR_exit(2), "%s: %s: %s",
SYSREDIR->nvname, e_badsyntax, com[1]);
UNREACHABLE();
}
else
type = (execflg && !shp->subshell && !shp->st.trapcom[0]);
shp->redir0 = 1;
@ -1749,8 +1755,11 @@ int sh_exec(register const Shnode_t *t, int flags)
if(fn<0)
{
if((errno = save_errno) != ENOENT)
{
errormsg(SH_DICT, ERROR_SYSTEM|ERROR_PANIC,
"process substitution: FIFO open failed");
UNREACHABLE();
}
sh_done(shp,0);
}
sh_iorenumber(shp,fn,fd);
@ -2408,7 +2417,10 @@ int sh_exec(register const Shnode_t *t, int flags)
#else
bt = times(&before);
if(bt == (clock_t)-1)
{
errormsg(SH_DICT, ERROR_exit(1), "times(3) failed: %s", strerror(errno));
UNREACHABLE();
}
#endif
job.waitall = 1;
sh_onstate(SH_TIMING);
@ -2431,7 +2443,10 @@ int sh_exec(register const Shnode_t *t, int flags)
#ifndef timeofday
at = times(&after) - bt;
if(at == (clock_t)-1)
{
errormsg(SH_DICT, ERROR_exit(1), "times(3) failed: %s", strerror(errno));
UNREACHABLE();
}
tm[0] = at;
#else
get_cpu_times(shp, &after_usr, &after_sys);
@ -2479,7 +2494,10 @@ int sh_exec(register const Shnode_t *t, int flags)
int offset = stktell(stkp);
int flags=NV_NOASSIGN|NV_NOARRAY|NV_VARNAME;
if(cp)
{
errormsg(SH_DICT,ERROR_exit(1),e_ident,fname);
UNREACHABLE();
}
sfputc(stkp,'.');
sfputr(stkp,fname,0);
np = nv_open(stkptr(stkp,offset),shp->var_tree,flags);
@ -2525,7 +2543,10 @@ int sh_exec(register const Shnode_t *t, int flags)
fname = stkptr(stkp,offset);
}
else if((mp=nv_search(fname,shp->bltin_tree,0)) && nv_isattr(mp,BLT_SPC))
{
errormsg(SH_DICT,ERROR_exit(1),e_badfun,fname);
UNREACHABLE();
}
#if SHOPT_NAMESPACE
if(shp->namespace && !shp->prefix && *fname!='.')
np = sh_fsearch(shp,fname,NV_ADD|HASH_NOSCOPE);
@ -2537,7 +2558,10 @@ int sh_exec(register const Shnode_t *t, int flags)
if(!shp->mktype)
cp = nv_setdisc(npv,cp,np,(Namfun_t*)npv);
if(!cp)
{
errormsg(SH_DICT,ERROR_exit(1),e_baddisc,fname);
UNREACHABLE();
}
}
if(np->nvalue.rp)
{
@ -2871,6 +2895,7 @@ pid_t _sh_fork(Shell_t *shp,register pid_t parent,int flags,int *jobid)
{
forkcnt=1000L;
errormsg(SH_DICT,ERROR_system(ERROR_NOEXEC),e_nofork);
UNREACHABLE();
}
timeout = (void*)sh_timeradd(forkcnt, 0, timed_out, NIL(void*));
nochild = job_wait((pid_t)1);
@ -3222,7 +3247,10 @@ int sh_funscope(int argn, char *argv[],int(*fun)(void*),void *arg,int execflg)
if(shp->topscope != (Shscope_t*)shp->st.self)
sh_setscope(shp->topscope);
if(--shp->fn_depth==1 && jmpval==SH_JMPERRFN)
{
errormsg(SH_DICT,ERROR_exit(1),e_toodeep,argv[0]);
UNREACHABLE();
}
sh_popcontext(shp,buffp);
sh_unscope(shp);
shp->namespace = nspace;
@ -3420,7 +3448,10 @@ static void coproc_init(Shell_t *shp, int pipes[])
{
int outfd;
if(shp->coutpipe>=0 && shp->cpid)
{
errormsg(SH_DICT,ERROR_exit(1),e_pexists);
UNREACHABLE();
}
shp->cpid = 0;
if(shp->cpipe[0]<=0 || shp->cpipe[1]<=0)
{
@ -3536,7 +3567,10 @@ static pid_t sh_ntfork(Shell_t *shp,const Shnode_t *t,char *argv[],int *jobid,in
}
}
else if(sh_isoption(SH_RESTRICTED))
{
errormsg(SH_DICT,ERROR_exit(1),e_restricted,path);
UNREACHABLE();
}
if(!path)
{
spawnpid = -1;
@ -3598,8 +3632,10 @@ static pid_t sh_ntfork(Shell_t *shp,const Shnode_t *t,char *argv[],int *jobid,in
{
case ENOENT:
errormsg(SH_DICT,ERROR_system(ERROR_NOENT),e_found+4);
UNREACHABLE();
default:
errormsg(SH_DICT,ERROR_system(ERROR_NOEXEC),e_exec+4);
UNREACHABLE();
}
job_unlock();
}