[PATCH 1/3] fprintf: Differentiate embedded flexible arrays from flexible arrays

[Arnaldo Carvalho de Melo <acme@kernel.org>]

From: Arnaldo Carvalho de Melo <acme@redhat.com>

Se one case where a struct has embedded flexible arrays, that was not
being notified as comments following those members:

  acme@x1:~/git/pahole$ pahole lirc_fh
  struct lirc_fh {
  	struct list_head           list;                 /*     0    16 */
  	struct rc_dev *            rc;                   /*    16     8 */
  	int                        carrier_low;          /*    24     4 */

  	/* XXX 4 bytes hole, try to pack */

  	struct {
  		union {
  			struct __kfifo kfifo;            /*    32    24 */
  			unsigned int * type;             /*    32     8 */
  			const unsigned int  * const_type; /*    32     8 */
  			char *     rectype;              /*    32     8 */
  			unsigned int * ptr;              /*    32     8 */
  			const unsigned int  * ptr_const; /*    32     8 */
  		};                                       /*    32    24 */
  		unsigned int       buf[];                /*    56     0 */
  	} rawir;                                         /*    32    24 */

  	/* XXX last struct has a flexible array */

  	struct {
  		union {
  			struct __kfifo kfifo;            /*    56    24 */
  			struct lirc_scancode * type;     /*    56     8 */
  			const struct lirc_scancode  * const_type; /*    56     8 */
  			char *     rectype;              /*    56     8 */
  			struct lirc_scancode * ptr;      /*    56     8 */
  			const struct lirc_scancode  * ptr_const; /*    56     8 */
  		};                                       /*    56    24 */
  		/* --- cacheline 1 boundary (64 bytes) was 16 bytes ago --- */
  		struct lirc_scancode buf[];              /*    80     0 */
  	} scancodes;                                     /*    56    24 */

  	/* XXX last struct has a flexible array */

  	wait_queue_head_t          wait_poll;            /*    80    24 */
  	u8                         send_mode;            /*   104     1 */
  	u8                         rec_mode;             /*   105     1 */

  	/* size: 112, cachelines: 2, members: 8 */
  	/* sum members: 102, holes: 1, sum holes: 4 */
  	/* padding: 6 */
  	/* last cacheline: 48 bytes */
  };

Now we need to count how many embedded flexible arrays are in a struct
to print at the end stats, right before that "last cacheline:" comment
line.

Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 dwarves_fprintf.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/dwarves_fprintf.c b/dwarves_fprintf.c
index 94a152183b0725cf..0d642a318fd836ef 100644
--- a/dwarves_fprintf.c
+++ b/dwarves_fprintf.c
@@ -1513,7 +1513,7 @@ static size_t class__fprintf_member_type_holes(struct class *class, const struct
 	size_t printed = 0;
 	uint16_t padding;
 	uint8_t nr_holes, nr_bit_holes, bit_padding;
-	bool first = true, has_embedded_flexible_array;
+	bool first = true, has_embedded_flexible_array, has_flexible_array;
 	/*
 	 * We may not yet have looked for holes and paddings in this member's
 	 * struct type.
@@ -1525,9 +1525,10 @@ static size_t class__fprintf_member_type_holes(struct class *class, const struct
 	bit_padding = class->bit_padding;
 	nr_holes = class->nr_holes;
 	nr_bit_holes = class->nr_bit_holes;
+	has_flexible_array = class__has_flexible_array(class, cu);
 	has_embedded_flexible_array = class__has_embedded_flexible_array(class, cu);
 
-	if (!padding && !bit_padding && !nr_holes && !nr_bit_holes && !has_embedded_flexible_array)
+	if (!padding && !bit_padding && !nr_holes && !nr_bit_holes && !has_flexible_array && !has_embedded_flexible_array)
 		return 0;
 
 	if (!(*newline)++) {
@@ -1537,11 +1538,16 @@ static size_t class__fprintf_member_type_holes(struct class *class, const struct
 
 	printed += fprintf(fp, "\n%.*s/* XXX last struct has", conf->indent, tabs);
 
-	if (has_embedded_flexible_array) {
+	if (has_flexible_array) {
 		printed += fprintf(fp, " a flexible array");
 		first = false;
 	}
 
+	if (has_embedded_flexible_array) {
+		printed += fprintf(fp, "%s embedded flexible array(s)", first ? "" : ",");
+		first = false;
+	}
+
 	if (padding) {
 		++holes->nr_paddings;
 		holes->sum_paddings += padding;
-- 
2.46.0