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From: Cupertino Miranda <cupertino.miranda@oracle.com>
To: gcc-patches@gcc.gnu.org
Cc: jose.marchesi@oracle.com, elena.zannoni@oracle.com,
	david.faust@oracle.com,
	Cupertino Miranda <cupertino.miranda@oracle.com>
Subject: [PATCH] Fixed problem with BTF defining smaller enums.
Date: Mon, 13 Nov 2023 22:37:39 +0000	[thread overview]
Message-ID: <20231113223739.11844-1-cupertino.miranda@oracle.com> (raw)

This patch fixes a BTF, which would become invalid when having
smaller then 4 byte definitions of enums.
For example, when using the __attribute__((mode(byte))) in the enum
definition.

Two problems were identified:
 - it would incorrectly create an entry for enum64 when the size of the
   enum was different then 4.
 - it would allocate less then 4 bytes for the value entry in BTF, in
   case the type was smaller.

BTF generated was validated against clang.

gcc/ChangeLog:
	* bpfout.cc (btf_calc_num_vbytes): Fixed logic for enum64.
	(btf_asm_enum_const): Corrected logic for enum64 and smaller
	than 4 bytes values.
---
 gcc/btfout.cc | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/gcc/btfout.cc b/gcc/btfout.cc
index e07fed302c24..d2263ec6eec3 100644
--- a/gcc/btfout.cc
+++ b/gcc/btfout.cc
@@ -299,7 +299,7 @@ btf_calc_num_vbytes (ctf_dtdef_ref dtd)
       break;
 
     case BTF_KIND_ENUM:
-      vlen_bytes += (dtd->dtd_data.ctti_size == 0x8)
+      vlen_bytes += (dtd->dtd_data.ctti_size > 4)
 			? vlen * sizeof (struct btf_enum64)
 			: vlen * sizeof (struct btf_enum);
       break;
@@ -914,13 +914,13 @@ btf_asm_enum_const (unsigned int size, ctf_dmdef_t * dmd, unsigned int idx)
 {
   dw2_asm_output_data (4, dmd->dmd_name_offset, "ENUM_CONST '%s' idx=%u",
 		       dmd->dmd_name, idx);
-  if (size == 4)
-    dw2_asm_output_data (size, dmd->dmd_value, "bte_value");
-  else
+  if (size > 4)
     {
-      dw2_asm_output_data (4, dmd->dmd_value & 0xffffffff, "bte_value_lo32");
+      dw2_asm_output_data (4, dmd->dmd_value & 0xfffffffe, "bte_value_lo32");
       dw2_asm_output_data (4, (dmd->dmd_value >> 32) & 0xffffffff, "bte_value_hi32");
     }
+  else
+    dw2_asm_output_data (size < 4 ? 4 : size, dmd->dmd_value, "bte_value");
 }
 
 /* Asm'out a function parameter description following a BTF_KIND_FUNC_PROTO.  */
-- 
2.30.2


             reply	other threads:[~2023-11-13 22:38 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-13 22:37 Cupertino Miranda [this message]
2023-11-14 16:28 ` David Faust
2023-11-27 17:21   ` [PATCH v2] " Cupertino Miranda
2023-11-27 19:01     ` David Faust
2023-11-28 12:57       ` Cupertino Miranda

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