[PATCH] Fortran: runtime bounds-checking in presence of array constructors [PR31059]

[PATCH] Fortran: runtime bounds-checking in presence of array constructors [PR31059]

[Harald Anlauf]

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Dear all,

gfortran's array bounds-checking code does a mostly reasonable
job for array sections in expressions and assignments, but
forgot the case that (rank-1) expressions can involve array
constructors, which have a shape ;-)

The attached patch walks over the loops generated by the
scalarizer, checks for the presence of a constructor, and
takes the first shape found as reference.  (If several
constructors are present, discrepancies in their shape
seems to be already detected at compile time).

For more details on what will be caught now see testcase.

Regtested on x86_64-pc-linux-gnu.  OK for mainline?

Thanks,
Harald


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From 944a35909e8eeb79c92e398ae3f27e94708584e6 Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anlauf@gmx.de>
Date: Thu, 31 Aug 2023 22:19:58 +0200
Subject: [PATCH] Fortran: runtime bounds-checking in presence of array
 constructors [PR31059]

gcc/fortran/ChangeLog:

	PR fortran/31059
	* trans-array.cc (gfc_conv_ss_startstride): For array bounds checking,
	consider also array constructors in expressions, and use their shape.

gcc/testsuite/ChangeLog:

	PR fortran/31059
	* gfortran.dg/bounds_check_fail_5.f90: New test.
---
 gcc/fortran/trans-array.cc                    | 23 ++++++++++++++++
 .../gfortran.dg/bounds_check_fail_5.f90       | 26 +++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 gcc/testsuite/gfortran.dg/bounds_check_fail_5.f90

diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index 90a7d4e9aef..6ca58e98547 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -4740,6 +4740,29 @@ done:
       for (n = 0; n < loop->dimen; n++)
 	size[n] = NULL_TREE;

+      /* If there is a constructor involved, derive size[] from its shape.  */
+      for (ss = loop->ss; ss != gfc_ss_terminator; ss = ss->loop_chain)
+	{
+	  gfc_ss_info *ss_info;
+
+	  ss_info = ss->info;
+	  info = &ss_info->data.array;
+
+	  if (ss_info->type == GFC_SS_CONSTRUCTOR && info->shape)
+	    {
+	      for (n = 0; n < loop->dimen; n++)
+		{
+		  if (size[n] == NULL)
+		    {
+		      gcc_assert (info->shape[n]);
+		      size[n] = gfc_conv_mpz_to_tree (info->shape[n],
+						      gfc_index_integer_kind);
+		    }
+		}
+	      break;
+	    }
+	}
+
       for (ss = loop->ss; ss != gfc_ss_terminator; ss = ss->loop_chain)
 	{
 	  stmtblock_t inner;
diff --git a/gcc/testsuite/gfortran.dg/bounds_check_fail_5.f90 b/gcc/testsuite/gfortran.dg/bounds_check_fail_5.f90
new file mode 100644
index 00000000000..436cc96621d
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/bounds_check_fail_5.f90
@@ -0,0 +1,26 @@
+! { dg-do run }
+! { dg-additional-options "-fcheck=bounds -g -fdump-tree-original" }
+! { dg-output "At line 13 .*" }
+! { dg-shouldfail "Array bound mismatch for dimension 1 of array 'ivec' (2/3)" }
+!
+! PR fortran/31059 - runtime bounds-checking in presence of array constructors
+
+program p
+  integer              :: jvec(3) = [1,2,3]
+  integer, allocatable :: ivec(:), kvec(:), lvec(:), mvec(:), nvec(:)
+  ivec    = [1,2]   ! (re)allocation
+  kvec    = [4,5,6] ! (re)allocation
+  ivec(:) = [4,5,6] ! runtime error (->dump)
+  ! not reached ...
+  print *, jvec + [1,2,3] ! OK & no check generated
+  print *, [4,5,6] + jvec ! OK & no check generated
+  print *, lvec + [1,2,3] ! check generated (->dump)
+  print *, [4,5,6] + mvec ! check generated (->dump)
+  nvec(:) = jvec          ! check generated (->dump)
+end
+
+! { dg-final { scan-tree-dump-times "Array bound mismatch " 4 "original" } }
+! { dg-final { scan-tree-dump-times "Array bound mismatch .*ivec" 1 "original" } }
+! { dg-final { scan-tree-dump-times "Array bound mismatch .*lvec" 1 "original" } }
+! { dg-final { scan-tree-dump-times "Array bound mismatch .*mvec" 1 "original" } }
+! { dg-final { scan-tree-dump-times "Array bound mismatch .*nvec" 1 "original" } }
--
2.35.3

Re: [PATCH] Fortran: runtime bounds-checking in presence of array constructors [PR31059]

[Mikael Morin]

Le 31/08/2023 à 22:42, Harald Anlauf via Fortran a écrit :
> Dear all,
> 
> gfortran's array bounds-checking code does a mostly reasonable
> job for array sections in expressions and assignments, but
> forgot the case that (rank-1) expressions can involve array
> constructors, which have a shape ;-)
> 
> The attached patch walks over the loops generated by the
> scalarizer, checks for the presence of a constructor, and
> takes the first shape found as reference.  (If several
> constructors are present, discrepancies in their shape
> seems to be already detected at compile time).
> 
> For more details on what will be caught now see testcase.
> 
> Regtested on x86_64-pc-linux-gnu.  OK for mainline?
> 
This is OK.

May I suggest to handle functions the same way?

Thanks.

> Thanks,
> Harald
> 

Re: [PATCH] Fortran: runtime bounds-checking in presence of array constructors [PR31059]

[Harald Anlauf]

Hi Mikael,

On 9/1/23 10:41, Mikael Morin via Gcc-patches wrote:
> Le 31/08/2023 à 22:42, Harald Anlauf via Fortran a écrit :
>> Dear all,
>>
>> gfortran's array bounds-checking code does a mostly reasonable
>> job for array sections in expressions and assignments, but
>> forgot the case that (rank-1) expressions can involve array
>> constructors, which have a shape ;-)
>>
>> The attached patch walks over the loops generated by the
>> scalarizer, checks for the presence of a constructor, and
>> takes the first shape found as reference.  (If several
>> constructors are present, discrepancies in their shape
>> seems to be already detected at compile time).
>>
>> For more details on what will be caught now see testcase.
>>
>> Regtested on x86_64-pc-linux-gnu.  OK for mainline?
>>
> This is OK.

I've pushed this is the first step.

> May I suggest to handle functions the same way?

I'll have a look at them, but will need to gather a few
suitable testcases first.

Thanks for the review!

Harald

>
> Thanks.
>
>> Thanks,
>> Harald
>>
>
>

Re: [PATCH] Fortran: runtime bounds-checking in presence of array constructors [PR31059]

[Mikael Morin]

Le 01/09/2023 à 22:48, Harald Anlauf a écrit :
> Hi Mikael,
> 
> On 9/1/23 10:41, Mikael Morin via Gcc-patches wrote:
>> May I suggest to handle functions the same way?
> 
> I'll have a look at them, but will need to gather a few
> suitable testcases first.
> 
I have just opened PR111339 
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111339) to track the case 
of functions separately.