Variables with the "noinit" attribute are ignored at -O0 because they
are treated like a regular bss variable and placed in the .bss section.
With -fdata-sections they are ignored because they are not handled in
resolve_unique_section.
Successfully regtested for arm-none-eabi.
Ok for trunk?
>From d501b36fc92f1506427836ded69997cc576beda4 Mon Sep 17 00:00:00 2001
From: Jozef Lawrynowicz <joze...@mittosystems.com>
Date: Sun, 15 Nov 2020 21:43:22 +0000
Subject: [PATCH 1/3] Fix "noinit" attribute being ignored for -O0 and
-fdata-sections
Variables with the "noinit" attribute are ignored at -O0 because they
are treated like a regular bss variable and placed in the .bss section.
With -fdata-sections they are ignored because they are not handled in
resolve_unique_section.
gcc/ChangeLog:
* tree.h (DECL_NOINIT_P): Define.
* varasm.c (DECL_NOINIT_P): Check DECL_NOINIT_P before using
unnamed bss/lcomm sections for bss_initializer variables.
(default_elf_select_section): Use DECL_NOINIT_P instead of
looking up attribute for .noinit section selection.
(default_unique_section): Check DECL_NOINIT_P for .noinit
section selection.
gcc/testsuite/ChangeLog:
* gcc.c-torture/execute/noinit-attribute.c: Don't override
optimization options set by torture test harness.
* lib/target-supports.exp (check_effective_target_noinit): Adjust
comment formatting.
---
gcc/testsuite/gcc.c-torture/execute/noinit-attribute.c | 2 +-
gcc/testsuite/lib/target-supports.exp | 2 +-
gcc/tree.h | 7 +++++++
gcc/varasm.c | 10 +++++++---
4 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/gcc/testsuite/gcc.c-torture/execute/noinit-attribute.c
b/gcc/testsuite/gcc.c-torture/execute/noinit-attribute.c
index 20a2a452e79..c8fa22bf38b 100644
--- a/gcc/testsuite/gcc.c-torture/execute/noinit-attribute.c
+++ b/gcc/testsuite/gcc.c-torture/execute/noinit-attribute.c
@@ -1,6 +1,6 @@
/* { dg-do run } */
/* { dg-require-effective-target noinit } */
-/* { dg-options "-O2" } */
+/* { dg-options "-Wattributes" } */
/* { dg-skip-if "data LMA != VMA" { msp430-*-* } { "-mlarge" } } */
/* This test checks that noinit data is handled correctly.
diff --git a/gcc/testsuite/lib/target-supports.exp
b/gcc/testsuite/lib/target-supports.exp
index 60ebbb39f9d..49c65b50109 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -368,7 +368,7 @@ proc check_weak_override_available { } {
return [check_weak_available]
}
-# The noinit attribute is only supported by some targets.
+# The "noinit" attribute is only supported by some targets.
# This proc returns 1 if it's supported, 0 if it's not.
proc check_effective_target_noinit { } {
diff --git a/gcc/tree.h b/gcc/tree.h
index f8f0a606439..f342731ae59 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -2659,6 +2659,13 @@ extern tree vector_element_bits_tree (const_tree);
#define DECL_PRESERVE_P(DECL) \
DECL_COMMON_CHECK (DECL)->decl_common.preserve_flag
+/* Nonzero for a decl that is decorated with the "noinit" attribute.
+ decls with this attribute are placed into the ".noinit" section, so they are
+ not initialized by the target's startup code. */
+#define DECL_NOINIT_P(DECL) \
+ (DECL_P (DECL) \
+ && (lookup_attribute ("noinit", DECL_ATTRIBUTES (DECL)) != NULL_TREE))
+
/* For function local variables of COMPLEX and VECTOR types,
indicates that the variable is not aliased, and that all
modifications to the variable have been adjusted so that
diff --git a/gcc/varasm.c b/gcc/varasm.c
index 435c7b348a5..3c902059069 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -1208,6 +1208,7 @@ get_variable_section (tree decl, bool prefer_noswitch_p)
if (ADDR_SPACE_GENERIC_P (as)
&& !DECL_THREAD_LOCAL_P (decl)
+ && !DECL_NOINIT_P (decl)
&& !(prefer_noswitch_p && targetm.have_switchable_bss_sections)
&& bss_initializer_p (decl))
{
@@ -7009,13 +7010,11 @@ default_elf_select_section (tree decl, int reloc,
sname = ".tdata";
break;
case SECCAT_BSS:
- if (DECL_P (decl)
- && lookup_attribute ("noinit", DECL_ATTRIBUTES (decl)) != NULL_TREE)
+ if (DECL_P (decl) && DECL_NOINIT_P (decl))
{
sname = ".noinit";
break;
}
-
if (bss_section)
return bss_section;
sname = ".bss";
@@ -7078,6 +7077,11 @@ default_unique_section (tree decl, int reloc)
prefix = one_only ? ".s" : ".sdata";
break;
case SECCAT_BSS:
+ if (DECL_P (decl) && DECL_NOINIT_P (decl))
+ {
+ prefix = one_only ? ".n" : ".noinit";
+ break;
+ }
prefix = one_only ? ".b" : ".bss";
break;
case SECCAT_SBSS:
--
2.29.2
