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Give GCC more control flow information, so it can be sure that

Browse source 
variables aren't used uninitialized.
* error.h (scm_error, scm_syserror, scm_syserror_msg,
scm_sysmissing, scm_num_overflow, scm_out_of_range,
scm_wrong_num_args, scm_wrong_type_arg, scm_memory_error,
scm_misc_error): Tell GCC that these functions never return.
* struct.c (scm_struct_ref, scm_struct_set_x): If we can't figure
out the field type, call abort if SCM_ASSERT returns, to placate
the optimizer.
* stacks.c (scm_make_stack, scm_last_stack_frame): abort if
scm_wta ever returns.  We can't handle this case anyway, and this
gives the optimizer more information.
* unif.c (scm_uniform_vector_ref, scm_array_set_x): Abort if
scm_wta ever returns.

In some cases, the code is fine, but GCC isn't smart enough to
figure that out; this usually happens when one variable is only
initialized and used when a particular condition holds true, and
we know that condition will never change within a given invocation
of the function.  In this case, we simply initialize the variables
to placate the compiler, hopefully to a value which will cause a
crash if it is ever actually used.
* print.c (scm_iprin1): Initialize mw_pos.
* read.c (scm_lreadrecparen): Initialize tl2, ans2.
* throw.c (scm_ithrow): Initialize dynpair.
* unif.c (scm_uniform_vector_ref): Initialize cra.
* struct.c (init_struct): Initialize prot.
* mbstrings.c (scm_print_mb_symbol): Initialize mw_pos and inc.
This commit is contained in:
Jim Blandy 1996-12-18 21:41:44 +00:00
parent 407775cb81
commit 35de7ebe4a
2 changed files with 25 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

4
libguile/struct.c
View file

@ -142,7 +142,7 @@ init_struct (handle, tail_elts, inits)
SCM layout;
SCM * data;
unsigned char * fields_desc;
unsigned char prot;
unsigned char prot = 0;
int n_fields;
SCM * mem;
int tailp = 0;
@ -456,6 +456,7 @@ scm_struct_ref (handle, pos)
else
{
SCM_ASSERT (0, pos, "ref denied", s_struct_ref);
abort ();
}
switch (field_type)
@ -532,6 +533,7 @@ scm_struct_set_x (handle, pos, val)
else
{
SCM_ASSERT (0, pos, "set_x denied", s_struct_ref);
abort ();
}
switch (field_type)

37
libguile/unif.c
View file

@ -469,7 +469,6 @@ scm_aind (ra, args, what)
register scm_sizet k = SCM_ARRAY_NDIM (ra);
scm_array_dim *s = SCM_ARRAY_DIMS (ra);
if (SCM_INUMP (args))
{
SCM_ASSERT (1 == k, scm_makfrom0str (what), SCM_WNA, NULL);
return pos + (SCM_INUM (args) - s->lbnd) * (s->inc);
@ -1041,14 +1040,13 @@ scm_uniform_vector_ref (v, args)
SCM args;
{
long pos;
if (SCM_IMP (v))
if (SCM_IMP (v))
{
SCM_ASRTGO (SCM_NULLP (args), badarg);
return v;
}
else if (SCM_ARRAYP (v))
{
pos = scm_aind (v, args, s_uniform_vector_ref);
v = SCM_ARRAY_V (v);
@ -1075,7 +1073,9 @@ scm_uniform_vector_ref (v, args)
default:
if (SCM_NULLP (args))
return v;
badarg:scm_wta (v, (char *) SCM_ARG1, s_uniform_vector_ref);
badarg:
scm_wta (v, (char *) SCM_ARG1, s_uniform_vector_ref);
abort ();
outrng:scm_out_of_range (s_uniform_vector_ref, SCM_MAKINUM (pos));
wna: scm_wrong_num_args (scm_makfrom0str (s_uniform_vector_ref));
case scm_tc7_smob:
@ -1236,7 +1236,6 @@ scm_array_set_x (v, obj, args)
long pos;
SCM_ASRTGO (SCM_NIMP (v), badarg1);
if (SCM_ARRAYP (v))
{
pos = scm_aind (v, args, s_array_set_x);
v = SCM_ARRAY_V (v);
@ -1244,7 +1243,6 @@ scm_array_set_x (v, obj, args)
else
{
if (SCM_NIMP (args))
{
SCM_ASSERT (SCM_CONSP (args) && SCM_INUMP (SCM_CAR (args)), args, SCM_ARG2, s_array_set_x);
pos = SCM_INUM (SCM_CAR (args));
@ -1259,8 +1257,9 @@ scm_array_set_x (v, obj, args)
}
switch (SCM_TYP7 (v))
{
default:
badarg1:scm_wta (v, (char *) SCM_ARG1, s_array_set_x);
default: badarg1:
scm_wta (v, (char *) SCM_ARG1, s_array_set_x);
abort ();
outrng:scm_out_of_range (s_array_set_x, SCM_MAKINUM (pos));
wna: scm_wrong_num_args (scm_makfrom0str (s_array_set_x));
case scm_tc7_smob: /* enclosed */
@ -1439,18 +1438,20 @@ scm_uniform_array_read_x (ra, port)
SCM ra;
SCM port;
{
SCM cra, v = ra;
SCM cra = SCM_UNDEFINED, v = ra;
long sz, len, ans;
long start = 0;
if (SCM_UNBNDP (port))
port = scm_cur_inp;
port = scm_cur_inp;
else
SCM_ASSERT (SCM_NIMP (port) && SCM_OPINFPORTP (port), port, SCM_ARG2, s_uniform_array_read_x);
SCM_ASSERT (SCM_NIMP (port) && SCM_OPINFPORTP (port), port, SCM_ARG2,
s_uniform_array_read_x);
SCM_ASRTGO (SCM_NIMP (v), badarg1);
len = SCM_LENGTH (v);
loop:
switch SCM_TYP7
(v)
switch SCM_TYP7 (v)
{
default:
badarg1:scm_wta (v, (char *) SCM_ARG1, s_uniform_array_read_x);
@ -1495,19 +1496,25 @@ loop:
break;
#endif
}
/* An ungetc before an fread will not work on some systems if setbuf(0).
do #define NOSETBUF in scmfig.h to fix this. */
if (SCM_CRDYP (port))
{ /* UGGH!!! */
ungetc (SCM_CGETUN (port), (FILE *)SCM_STREAM (port));
SCM_CLRDY (port); /* Clear ungetted char */
}
SCM_SYSCALL (ans = fread (SCM_CHARS (v) + start * sz, (scm_sizet) sz, (scm_sizet) len, (FILE *)SCM_STREAM (port)));
SCM_SYSCALL (ans = fread (SCM_CHARS (v) + start * sz,
(scm_sizet) sz, (scm_sizet) len,
(FILE *)SCM_STREAM (port)));
if (SCM_TYP7 (v) == scm_tc7_bvect)
ans *= SCM_LONG_BIT;
if (v != ra && cra != ra)
scm_array_copy_x (cra, ra);
return SCM_MAKINUM (ans);
}