Thread (13 messages) flat view 13 messages, 4 authors, 2019-11-16

Re: [Cocci] git-coccinelle: adjustments for array.cocci?

From: Julia Lawall <hidden>
Date: 2019-11-16 17:57:43
Also in: cocci


On Fri, 15 Nov 2019, Markus Elfring wrote:
quoted hunk ↗ jump to hunk
quoted
Anyway, someone who can reproduce the issue using the latest release
of Coccinelle would be in a better position to file a bug report.
Hello,

I repeated the discussed source code transformation approach together
with the software combination “Coccinelle 1.0.8-00004-g842075f7” (OCaml 4.09).
https://github.com/coccinelle/coccinelle/commits/master

1. Yesterday I checked the source files out for the software “Git”
   according to the commit “The first batch post 2.24 cycle”.
   https://github.com/git/git/commit/d9f6f3b6195a0ca35642561e530798ad1469bd41

2. I restored a previous development status by the following command.

   git show 921d49be86 | patch -p1 -R

   See also:
   https://public-inbox.org/git/53346d52-e096-c651-f70a-ce6ca4d82ff9@web.de/

3. I stored a generated patch based on the currently released SmPL script.
   https://github.com/git/git/blob/177fbab747da4f58cb2a8ce010b3515c86dd67c9/contrib/coccinelle/array.cocci

4. I applied the following patch then.
diff --git a/contrib/coccinelle/array.cocci b/contrib/coccinelle/array.cocci
index 46b8d2ee11..89df184bbd 100644
--- a/contrib/coccinelle/array.cocci
+++ b/contrib/coccinelle/array.cocci
@@ -12,27 +12,21 @@ T *ptr;
 T[] arr;
 expression E, n;
 @@
-(
-  memcpy(ptr, E,
-- n * sizeof(*(ptr))
-+ n * sizeof(T)
-  )
-|
-  memcpy(arr, E,
-- n * sizeof(*(arr))
-+ n * sizeof(T)
-  )
-|
-  memcpy(E, ptr,
-- n * sizeof(*(ptr))
-+ n * sizeof(T)
-  )
-|
-  memcpy(E, arr,
-- n * sizeof(*(arr))
-+ n * sizeof(T)
-  )
+ memcpy(
+(       ptr, E, n *
+-       sizeof(*(ptr))
++       sizeof(T)
+|       arr, E, n *
+-       sizeof(*(arr))
++       sizeof(T)
+|       E, ptr, n *
+-       sizeof(*(ptr))
++       sizeof(T)
+|       E, arr, n *
+-       sizeof(*(arr))
++       sizeof(T)
 )
+       )
This seems quite unreadable, in contrast to the original code.
 @@
 type T;

   I suggested in this way to move a bit of SmPL code.

5. I stored another generated patch based on the adjusted SmPL script.
No idea what it means to store a patch.
quoted hunk ↗ jump to hunk
6. I performed a corresponding file comparison.
--- array-released.diff	2019-11-14 21:29:11.020576916 +0100
+++ array-reduced1.diff	2019-11-14 21:45:58.931956527 +0100
@@ -6,24 +6,10 @@
  	r->entry_count = t->entry_count;
  	r->delta_depth = t->delta_depth;
 -	memcpy(r->entries,t->entries,t->entry_count*sizeof(t->entries[0]));
-+	COPY_ARRAY(r->entries, t->entries, t->entry_count);
++	memcpy(r->entries,t->entries,t->entry_count*sizeof(*(t->entries)));
  	release_tree_content(t);
  	return r;
  }
I have no idea what is being compared here. The COPY_ARRAY thing looks
nice, but doesn't seem to have anything to do with your semantic patch.

julia


quoted hunk ↗ jump to hunk
-diff -u -p a/pretty.c b/pretty.c
---- a/pretty.c
-+++ b/pretty.c
-@@ -106,8 +106,8 @@ static void setup_commit_formats(void)
- 	commit_formats_len = ARRAY_SIZE(builtin_formats);
- 	builtin_formats_len = commit_formats_len;
- 	ALLOC_GROW(commit_formats, commit_formats_len, commit_formats_alloc);
--	memcpy(commit_formats, builtin_formats,
--	       sizeof(*builtin_formats)*ARRAY_SIZE(builtin_formats));
-+	COPY_ARRAY(commit_formats, builtin_formats,
-+		   ARRAY_SIZE(builtin_formats));
-
- 	git_config(git_pretty_formats_config, NULL);
- }
 diff -u -p a/packfile.c b/packfile.c
 --- a/packfile.c
 +++ b/packfile.c
@@ -36,17 +22,6 @@
  		} else {
  			ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
  		}
-@@ -1698,8 +1698,8 @@ void *unpack_entry(struct repository *r,
- 		    && delta_stack == small_delta_stack) {
- 			delta_stack_alloc = alloc_nr(delta_stack_nr);
- 			ALLOC_ARRAY(delta_stack, delta_stack_alloc);
--			memcpy(delta_stack, small_delta_stack,
--			       sizeof(*delta_stack)*delta_stack_nr);
-+			COPY_ARRAY(delta_stack, small_delta_stack,
-+				   delta_stack_nr);
- 		} else {
- 			ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
- 		}
 diff -u -p a/compat/regex/regexec.c b/compat/regex/regexec.c
 --- a/compat/regex/regexec.c
 +++ b/compat/regex/regexec.c

How do you think about the differences from this test result?

Regards,
Markus
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