PR fortran/91300 - runtime error message with allocate and errmsg=
Commit Message
Dear Fortranners,
the PR rightfully complained that we did not differentiate errors on
ALLOCATE(...,stat=,errmsg=) for failures from allocation of already
allocated objects or insufficient virtual memory.
The attached patch introduces a new STAT value LIBERROR_NO_MEMORY
that is returned for insufficient virtual memory, and a corresponding
(simple and invariant) ERRMSG: "Insufficient virtual memory".
(In the PR Janne mentions checking for errno, but since the standard
malloc(3) only mentions ENOMEM as possible error value, and the user
may replace malloc by a special library, I believe that won't be easy
to handle in a general way.)
Most compilers I tried (Intel/NAG/Crayftn) behave similarly, except
for Nvidia/Flang, which try to return the size of the allocation in
the error message.
I am not sure that this is worth the effort. First, ERRMSG is very
compiler-dependent anyway and thus not really portable. If a user
wants to know what the size of the failed allocation is and really
wants to recover, he/she should find that out himself. Second, I
think that the more important change is the introduction of a STAT
value that allows the distinction between the different causes of
failure.
The testcase should be able to handle 32 and 64 bit systems.
At least that's what I think.
Regtested on x86_64-pc-linux-gnu. OK for mainline? Suggestions?
Thanks,
Harald
Comments
On 28.05.22 22:25, Harald Anlauf via Fortran wrote:
> the PR rightfully complained that we did not differentiate errors on
> ALLOCATE(...,stat=,errmsg=) for failures from allocation of already
> allocated objects or insufficient virtual memory.
It is even worse: The error message states the wrong reason.
> The attached patch introduces a new STAT value LIBERROR_NO_MEMORY
> that is returned for insufficient virtual memory, and a corresponding
> (simple and invariant) ERRMSG: "Insufficient virtual memory".
I think the message is fine – at least on Linux 'virtual memory' is
what's used and it is clear what's meant, even if I stumble a bit about
the wording. (But do not have a crisp short & comprehensive wording myself.)
> (In the PR Janne mentions checking for errno, but since the standard
> malloc(3) only mentions ENOMEM as possible error value, and the user
> may replace malloc by a special library, I believe that won't be easy
> to handle in a general way.)
I con concur. Especially as POSIX and the Linux manpage only list ENOMEM
as only value.
> Most compilers I tried (Intel/NAG/Crayftn) behave similarly, except
> for Nvidia/Flang, which try to return the size of the allocation in
> the error message.
>
> I am not sure that this is worth the effort.
I think it is not needed – especially as we generate the message in the
FE and not in libgfortran. The advantage for the users is that they know
what value has been requested – but they cannot really do much with the
knowledge, either.
> The testcase should be able to handle 32 and 64 bit systems.
> At least that's what I think.
I hope it is – at least on 64bit, I currently expect it too fail
somewhat reliably, with 32bit I think it won't – but that's also handled.
But you could add a -fdump-tree-original + '! { dg-final {
scan-tree-dump*' to do some checking in addition (e.g. whether both
strings appear in the dump; could be more complex, but that's probably
not needed).
> Regtested on x86_64-pc-linux-gnu. OK for mainline? Suggestions?
LGTM – with considering comments on the testcase.
> Fortran: improve runtime error message with ALLOCATE and ERRMSG=
Consider appending [PR91300] in that line – and try to make the
gcc-patches@ and fortran@ lines the same
(Searching for the PR number or case-insignificantly for the string in
the mailing list archive, will fine the message; thus, that's okay.)
> ALLOCATE: generate different STAT,ERRMSG results for failures from
> allocation of already allocated objects or insufficient virtual memory.
>
> gcc/fortran/ChangeLog:
>
> PR fortran/91300
> * libgfortran.h: Define new error code LIBERROR_NO_MEMORY.
> * trans-stmt.cc (gfc_trans_allocate): Generate code for setting
> ERRMSG depending on result of STAT result of ALLOCATE.
> * trans.cc (gfc_allocate_using_malloc): Use STAT value of
> LIBERROR_NO_MEMORY in case of failed malloc.
>
> gcc/testsuite/ChangeLog:
>
> PR fortran/91300
> * gfortran.dg/allocate_alloc_opt_15.f90: New test.
> ---
...
> + stat1 = -1
> + errmsg1 = ""
> + allocate (array(1), stat=stat1, errmsg=errmsg1)
> + if (stat1 /= 0) stop 1
> + if (errmsg1 /= "") stop 1
Consider to init the errmsg1 and then check that is has not been
touched. (For completeness, I think we already have such tests).
> + ! Obtain stat,errmsg for attempt to allocate an allocated object
> + allocate (array(1), stat=stat1, errmsg=errmsg1)
> + if (stat1 == 0) stop 2
> + if (errmsg1 == "") stop 2
Consider to check (either here or as a third test) for the
gfortran-specific error message.
> + stat2 = -1
> + errmsg2 = ""
> + ! Try to allocate very large object
> + allocate (bigarray(bignumber), stat=stat2, errmsg=errmsg2)
> + if (stat2 /= 0) then
> + print *, "stat =", stat1
> + print *, "errmsg: ", trim (errmsg1)
> + print *, "stat =", stat2
> + print *, "errmsg: ", trim (errmsg2)
> + ! Ensure different results for stat, errmsg variables
> + if (stat2 == stat1 ) stop 3
> + if (errmsg2 == "" .or. errmsg2 == errmsg1) stop 4
Likewise for errmsg2
Thanks,
Tobias
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From 19ccd22ee9359bd14b32a95bd9efcaead3593b2f Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anlauf@gmx.de>
Date: Sat, 28 May 2022 22:02:20 +0200
Subject: [PATCH] Fortran: improve runtime error message with ALLOCATE and
ERRMSG=
ALLOCATE: generate different STAT,ERRMSG results for failures from
allocation of already allocated objects or insufficient virtual memory.
gcc/fortran/ChangeLog:
PR fortran/91300
* libgfortran.h: Define new error code LIBERROR_NO_MEMORY.
* trans-stmt.cc (gfc_trans_allocate): Generate code for setting
ERRMSG depending on result of STAT result of ALLOCATE.
* trans.cc (gfc_allocate_using_malloc): Use STAT value of
LIBERROR_NO_MEMORY in case of failed malloc.
gcc/testsuite/ChangeLog:
PR fortran/91300
* gfortran.dg/allocate_alloc_opt_15.f90: New test.
---
gcc/fortran/libgfortran.h | 1 +
gcc/fortran/trans-stmt.cc | 33 +++++++++++++--
gcc/fortran/trans.cc | 4 +-
.../gfortran.dg/allocate_alloc_opt_15.f90 | 40 +++++++++++++++++++
4 files changed, 73 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/gfortran.dg/allocate_alloc_opt_15.f90
@@ -133,6 +133,7 @@ typedef enum
LIBERROR_CORRUPT_FILE,
LIBERROR_INQUIRE_INTERNAL_UNIT, /* Must be different from STAT_STOPPED_IMAGE. */
LIBERROR_BAD_WAIT_ID,
+ LIBERROR_NO_MEMORY,
LIBERROR_LAST /* Not a real error, the last error # + 1. */
}
libgfortran_error_codes;
@@ -7130,7 +7130,8 @@ gfc_trans_allocate (gfc_code * code)
if (code->expr1 && code->expr2)
{
const char *msg = "Attempt to allocate an allocated object";
- tree slen, dlen, errmsg_str;
+ const char *oommsg = "Insufficient virtual memory";
+ tree slen, dlen, errmsg_str, oom_str, oom_loc;
stmtblock_t errmsg_block;
gfc_init_block (&errmsg_block);
@@ -7151,8 +7152,34 @@ gfc_trans_allocate (gfc_code * code)
gfc_default_character_kind);
dlen = gfc_finish_block (&errmsg_block);
- tmp = fold_build2_loc (input_location, NE_EXPR, logical_type_node,
- stat, build_int_cst (TREE_TYPE (stat), 0));
+ tmp = fold_build2_loc (input_location, EQ_EXPR, logical_type_node,
+ stat, build_int_cst (TREE_TYPE (stat),
+ LIBERROR_ALLOCATION));
+
+ tmp = build3_v (COND_EXPR, tmp,
+ dlen, build_empty_stmt (input_location));
+
+ gfc_add_expr_to_block (&block, tmp);
+
+ oom_str = gfc_create_var (pchar_type_node, "OOMMSG");
+ oom_loc = gfc_build_localized_cstring_const (oommsg);
+ gfc_add_modify (&errmsg_block, oom_str,
+ gfc_build_addr_expr (pchar_type_node, oom_loc));
+
+ slen = build_int_cst (gfc_charlen_type_node, strlen (oommsg));
+ dlen = gfc_get_expr_charlen (code->expr2);
+ slen = fold_build2_loc (input_location, MIN_EXPR,
+ TREE_TYPE (slen), dlen, slen);
+
+ gfc_trans_string_copy (&errmsg_block, dlen, errmsg,
+ code->expr2->ts.kind,
+ slen, oom_str,
+ gfc_default_character_kind);
+ dlen = gfc_finish_block (&errmsg_block);
+
+ tmp = fold_build2_loc (input_location, EQ_EXPR, logical_type_node,
+ stat, build_int_cst (TREE_TYPE (stat),
+ LIBERROR_NO_MEMORY));
tmp = build3_v (COND_EXPR, tmp,
dlen, build_empty_stmt (input_location));
@@ -772,7 +772,7 @@ gfc_call_malloc (stmtblock_t * block, tree type, tree size)
if (newmem == NULL)
{
if (stat)
- *stat = LIBERROR_ALLOCATION;
+ *stat = LIBERROR_NO_MEMORY;
else
runtime_error ("Allocation would exceed memory limit");
}
@@ -807,7 +807,7 @@ gfc_allocate_using_malloc (stmtblock_t * block, tree pointer,
if (status != NULL_TREE)
{
tmp = fold_build2_loc (input_location, MODIFY_EXPR, status_type, status,
- build_int_cst (status_type, LIBERROR_ALLOCATION));
+ build_int_cst (status_type, LIBERROR_NO_MEMORY));
gfc_add_expr_to_block (&on_error, tmp);
}
else
new file mode 100644
@@ -0,0 +1,40 @@
+! { dg-do run }
+! PR fortran/91300 - runtime error message with allocate and errmsg=
+! Contributed by zed.three
+
+program bigarray_prog
+ use, intrinsic :: iso_c_binding, only: C_INTPTR_T
+ implicit none
+ real, dimension(:), allocatable :: array, bigarray
+ integer :: stat1, stat2
+ character(len=100) :: errmsg1, errmsg2
+ integer(8), parameter :: n1 = huge (1) / 3 ! request more than 2GB
+ integer(8), parameter :: n2 = huge (1_C_INTPTR_T) / 4 ! "safe" for 64bit
+ integer(8), parameter :: bignumber = max (n1, n2)
+
+ stat1 = -1
+ errmsg1 = ""
+ allocate (array(1), stat=stat1, errmsg=errmsg1)
+ if (stat1 /= 0) stop 1
+ if (errmsg1 /= "") stop 1
+
+ ! Obtain stat,errmsg for attempt to allocate an allocated object
+ allocate (array(1), stat=stat1, errmsg=errmsg1)
+ if (stat1 == 0) stop 2
+ if (errmsg1 == "") stop 2
+
+ stat2 = -1
+ errmsg2 = ""
+ ! Try to allocate very large object
+ allocate (bigarray(bignumber), stat=stat2, errmsg=errmsg2)
+ if (stat2 /= 0) then
+ print *, "stat =", stat1
+ print *, "errmsg: ", trim (errmsg1)
+ print *, "stat =", stat2
+ print *, "errmsg: ", trim (errmsg2)
+ ! Ensure different results for stat, errmsg variables
+ if (stat2 == stat1 ) stop 3
+ if (errmsg2 == "" .or. errmsg2 == errmsg1) stop 4
+ end if
+
+end program bigarray_prog
--
2.35.3