[PATCH] Preserve location in gimple_fold_builtin_memset

[PATCH] Preserve location in gimple_fold_builtin_memset

[Jakub Jelinek]

Hi!

As mentioned yesterday, gimple_fold_builtin_memset doesn't preserve
locus which means e.g. the -Wstringop-overflow warnings are emitted as:
In function 'test_max':
cc1: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=]
The function emits up to 2 new statements, but the latter (asgn) is added
through gsi_replace and therefore the locus is copied over from the call.
But store is emitted before the call and optionally the call removed
afterwards, so locus needs to be copied over manually.

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?

2021-10-29  Jakub Jelinek  <jakub@redhat.com>

	* gimple-fold.c (gimple_fold_builtin_memset): Copy over location from
	call to store.

	* gcc.dg/Wstringop-overflow-62.c: Adjust expected diagnostics.

--- gcc/gimple-fold.c.jj	2021-10-12 09:36:57.728450483 +0200
+++ gcc/gimple-fold.c	2021-10-28 12:42:07.638741783 +0200
@@ -1505,6 +1505,7 @@ gimple_fold_builtin_memset (gimple_stmt_
   var = fold_build2 (MEM_REF, etype, dest, build_int_cst (ptr_type_node, 0));
   gimple *store = gimple_build_assign (var, build_int_cst_type (etype, cval));
   gimple_move_vops (store, stmt);
+  gimple_set_location (store, gimple_location (stmt));
   gsi_insert_before (gsi, store, GSI_SAME_STMT);
   if (gimple_call_lhs (stmt))
     {
--- gcc/testsuite/gcc.dg/Wstringop-overflow-62.c.jj	2021-10-28 12:24:21.909780099 +0200
+++ gcc/testsuite/gcc.dg/Wstringop-overflow-62.c	2021-10-28 12:43:52.023273297 +0200
@@ -223,7 +223,7 @@ void test_max (void)
 
     char *q = MAX (pi, pj);
 
-    memset (q, 0, 1);         // { dg-warning "writing 1 byte into a region of size 0 " "" { target *-*-* } 0 }
+    memset (q, 0, 1);         // { dg-warning "writing 1 byte into a region of size 0 " }
     memset (q, 0, 2);         // { dg-warning "writing 2 bytes into a region of size 0 " }
   }
 
@@ -345,7 +345,7 @@ void test_max (void)
        not reflected in the determaxed offset).  */
     char *q = MAX (p1, p2);
 
-    memset (q, 0, 1);
+    memset (q, 0, 1);         // { dg-warning "writing 1 byte into a region of size 0 " }
   }
 
   {

	Jakub

Re: [PATCH] Preserve location in gimple_fold_builtin_memset

[Richard Biener]

On Fri, 29 Oct 2021, Jakub Jelinek wrote:

> Hi!
> 
> As mentioned yesterday, gimple_fold_builtin_memset doesn't preserve
> locus which means e.g. the -Wstringop-overflow warnings are emitted as:
> In function 'test_max':
> cc1: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=]
> The function emits up to 2 new statements, but the latter (asgn) is added
> through gsi_replace and therefore the locus is copied over from the call.
> But store is emitted before the call and optionally the call removed
> afterwards, so locus needs to be copied over manually.
> 
> Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
> trunk?

OK.

Thanks,
Richard.

> 2021-10-29  Jakub Jelinek  <jakub@redhat.com>
> 
> 	* gimple-fold.c (gimple_fold_builtin_memset): Copy over location from
> 	call to store.
> 
> 	* gcc.dg/Wstringop-overflow-62.c: Adjust expected diagnostics.
> 
> --- gcc/gimple-fold.c.jj	2021-10-12 09:36:57.728450483 +0200
> +++ gcc/gimple-fold.c	2021-10-28 12:42:07.638741783 +0200
> @@ -1505,6 +1505,7 @@ gimple_fold_builtin_memset (gimple_stmt_
>    var = fold_build2 (MEM_REF, etype, dest, build_int_cst (ptr_type_node, 0));
>    gimple *store = gimple_build_assign (var, build_int_cst_type (etype, cval));
>    gimple_move_vops (store, stmt);
> +  gimple_set_location (store, gimple_location (stmt));
>    gsi_insert_before (gsi, store, GSI_SAME_STMT);
>    if (gimple_call_lhs (stmt))
>      {
> --- gcc/testsuite/gcc.dg/Wstringop-overflow-62.c.jj	2021-10-28 12:24:21.909780099 +0200
> +++ gcc/testsuite/gcc.dg/Wstringop-overflow-62.c	2021-10-28 12:43:52.023273297 +0200
> @@ -223,7 +223,7 @@ void test_max (void)
>  
>      char *q = MAX (pi, pj);
>  
> -    memset (q, 0, 1);         // { dg-warning "writing 1 byte into a region of size 0 " "" { target *-*-* } 0 }
> +    memset (q, 0, 1);         // { dg-warning "writing 1 byte into a region of size 0 " }
>      memset (q, 0, 2);         // { dg-warning "writing 2 bytes into a region of size 0 " }
>    }
>  
> @@ -345,7 +345,7 @@ void test_max (void)
>         not reflected in the determaxed offset).  */
>      char *q = MAX (p1, p2);
>  
> -    memset (q, 0, 1);
> +    memset (q, 0, 1);         // { dg-warning "writing 1 byte into a region of size 0 " }
>    }
>  
>    {
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)