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Re: [patch, fortran] PR66310 Problems with intrinsic repeat for large number of copies
On 07/19/2016 02:56 AM, Dominique d'Humières wrote:
>
>> Le 18 juil. 2016 à 02:02, Jerry DeLisle <jvdelisle@charter.net> a écrit :
>>
>> Please test this revised patch. See my comments in the PR.
>>
>> I think we should commit this one.
>>
>> Jerry
>
> Jerry,
>
See latest patch attached. Fixes a few things and documents a TODO
Jerry
> As said on IRC I think the limit should be documented and a TODO comment added to gcc/fortran/gfortran.h.
>
> While trying to bootstrap with the patch I got
>
> /opt/gcc/build_w/./prev-gcc/xg++ -B/opt/gcc/build_w/./prev-gcc/ -B/opt/gcc/gcc7w/x86_64-apple-darwin15.5.0/bin/ -nostdinc++ -B/opt/gcc/build_w/prev-x86_64-apple-darwin15.5.0/libstdc++-v3/src/.libs -B/opt/gcc/build_w/prev-x86_64-apple-darwin15.5.0/libstdc++-v3/libsupc++/.libs -I/opt/gcc/build_w/prev-x86_64-apple-darwin15.5.0/libstdc++-v3/include/x86_64-apple-darwin15.5.0 -I/opt/gcc/build_w/prev-x86_64-apple-darwin15.5.0/libstdc++-v3/include -I/opt/gcc/work/libstdc++-v3/libsupc++ -L/opt/gcc/build_w/prev-x86_64-apple-darwin15.5.0/libstdc++-v3/src/.libs -L/opt/gcc/build_w/prev-x86_64-apple-darwin15.5.0/libstdc++-v3/libsupc++/.libs -fno-PIE -c -DIN_GCC_FRONTEND -g -O2 -gtoggle -DIN_GCC -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wmissing-format-attribute -Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings -Werror -fno-common -DHAVE_CONFIG_H -I. -Ifortran -I../../work/gcc -I../../work/gcc/fortran -I../../work/gcc/../include -I./../intl -I../../work/gcc/../libcpp/include -I/opt/mp-new/include -I../../work/gcc/../libdecnumber -I../../work/gcc/../libdecnumber/dpd -I../libdecnumber -I../../work/gcc/../libbacktrace -I/opt/mp-new/include -o fortran/simplify.o -MT fortran/simplify.o -MMD -MP -MF fortran/.deps/simplify.TPo ../../work/gcc/fortran/simplify.c
> ../../work/gcc/fortran/simplify.c: In function 'gfc_expr* gfc_simplify_repeat(gfc_expr*, gfc_expr*)':
> ../../work/gcc/fortran/simplify.c:5089:11: error: variable 'i' set but not used [-Werror=unused-but-set-variable]
> int i;
> ^
> cc1plus: all warnings being treated as errors
>
> i.e., the lines
>
> int i;
>
> and
>
> i = gfc_validate_kind (BT_INTEGER, gfc_charlen_int_kind, false);
>
> must be deleted. also the comment
>
> /* Compute the maximum value allowed for NCOPIES:
> huge(cl) - 1 / len. */
>
> should be updated.
>
> Last point I have found, the limit does not seem to take into account CHARACTER(KIND=4):
>
> [Book15] f90/bug% cat pr66310_par_4.f90
> program p
> character(len=2,kind=4), parameter :: z = 'yz'
> print *, repeat(z, 2**25)
> end
> [Book15] f90/bug% gfc pr66310_par_4.f90
> f951(3881,0x7fff74e38000) malloc: *** mach_vm_map(size=18446744073441116160) failed (error code=3)
> *** error: can't allocate region
> *** set a breakpoint in malloc_error_break to debug
>
> f951: out of memory allocating 18446744073441116160 bytes after a total of 0 bytes
>
> Thanks for working on this PR.
>
> Dominique
>
diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index 77831ab..c0b73c7 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -59,6 +59,11 @@ not after.
#define MAX_SUBRECORD_LENGTH 2147483639 /* 2**31-9 */
+/* TODO: Why does the compilation fail with the following set >= 2**28 when
+ the repeat source is a character constant (aka parameter)? See PR66310. */
+
+/* Practical limit on size of character constants in gfc_simplify_repeat. */
+#define MAX_CHAR_LENGTH 268435455 /* 2**28-1 */
#define gfc_is_whitespace(c) ((c==' ') || (c=='\t'))
diff --git a/gcc/fortran/simplify.c b/gcc/fortran/simplify.c
index 8096a92..348bccc 100644
--- a/gcc/fortran/simplify.c
+++ b/gcc/fortran/simplify.c
@@ -5085,24 +5085,33 @@ gfc_simplify_repeat (gfc_expr *e, gfc_expr *n)
/* Check that NCOPIES isn't too large. */
if (len)
{
- mpz_t max, mlen;
+ mpz_t max, mlen, limit;
int i;
- /* Compute the maximum value allowed for NCOPIES: huge(cl) / len. */
+ /* Compute the maximum value allowed for NCOPIES:
+ huge(cl) - 1 / len. */
mpz_init (max);
+ mpz_init (limit);
i = gfc_validate_kind (BT_INTEGER, gfc_charlen_int_kind, false);
+ /* Set the limit on size to avoid unsigned integer
+ wrapping and resource limits. */
+ if (e->expr_type != EXPR_CONSTANT)
+ mpz_sub_ui (limit, gfc_integer_kinds[i].huge, 1);
+ else
+ mpz_set_si (limit, MAX_CHAR_LENGTH);
+
if (have_length)
{
- mpz_tdiv_q (max, gfc_integer_kinds[i].huge,
- e->ts.u.cl->length->value.integer);
+ mpz_tdiv_q (max, limit, e->ts.u.cl->length->value.integer);
}
else
{
mpz_init_set_si (mlen, len);
- mpz_tdiv_q (max, gfc_integer_kinds[i].huge, mlen);
+ mpz_tdiv_q (max, limit, mlen);
mpz_clear (mlen);
}
+ mpz_clear (limit);
/* The check itself. */
if (mpz_cmp (ncopies, max) > 0)
diff --git a/gcc/testsuite/gfortran.dg/repeat_4.f90 b/gcc/testsuite/gfortran.dg/repeat_4.f90
index e5b5acc..771e7f0 100644
--- a/gcc/testsuite/gfortran.dg/repeat_4.f90
+++ b/gcc/testsuite/gfortran.dg/repeat_4.f90
@@ -22,17 +22,17 @@ program test
! Check for too large NCOPIES argument and limit cases
print *, repeat(t0, huge(0))
- print *, repeat(t1, huge(0))
+ print *, repeat(t1, huge(0)) ! { dg-error "Argument NCOPIES of REPEAT intrinsic is too large " }
print *, repeat(t2, huge(0)) ! { dg-error "Argument NCOPIES of REPEAT intrinsic is too large " }
print *, repeat(s2, huge(0)) ! { dg-error "Argument NCOPIES of REPEAT intrinsic is too large " }
- print *, repeat(t0, huge(0)/2)
- print *, repeat(t1, huge(0)/2)
+ print *, repeat(t0, huge(0)-1)
+ print *, repeat(t1, huge(0)-1)
print *, repeat(t2, huge(0)/2)
print *, repeat(t0, huge(0)/2+1)
- print *, repeat(t1, huge(0)/2+1)
- print *, repeat(t2, huge(0)/2+1) ! { dg-error "Argument NCOPIES of REPEAT intrinsic is too large " }
- print *, repeat(s2, huge(0)/2+1) ! { dg-error "Argument NCOPIES of REPEAT intrinsic is too large " }
+ print *, repeat(t1, huge(0)) ! { dg-error "Argument NCOPIES of REPEAT intrinsic is too large " }
+ print *, repeat(t2, huge(0)) ! { dg-error "Argument NCOPIES of REPEAT intrinsic is too large " }
+ print *, repeat(s2, huge(0)/16+1)! { dg-error "Argument NCOPIES of REPEAT intrinsic is too large " }
end program test