@@ -10,7 +10,7 @@ OTHER_TEXT_SECTIONS='*(.glue_7t) *(.glue_7) *(.vfp11_veneer) *(.v4_bx)'
OTHER_BSS_SYMBOLS="${CREATE_SHLIB+PROVIDE (}__bss_start__ = .${CREATE_SHLIB+)};"
OTHER_BSS_END_SYMBOLS="${CREATE_SHLIB+PROVIDE (}_bss_end__ = .${CREATE_SHLIB+)}; ${CREATE_SHLIB+PROVIDE (}__bss_end__ = .${CREATE_SHLIB+)};"
OTHER_END_SYMBOLS="${CREATE_SHLIB+PROVIDE (}__end__ = .${CREATE_SHLIB+)};"
-OTHER_SECTIONS='
+OTHER_SECTIONS="
.note.gnu.arm.ident 0 : { KEEP (*(.note.gnu.arm.ident)) }
/* This section contains data that is not initialised during load
*or* application reset. */
@@ -18,11 +18,21 @@ OTHER_SECTIONS='
{
. = ALIGN(2);
PROVIDE (__noinit_start = .);
- *(.noinit)
+ *(.noinit${RELOCATING+ .noinit.* .gnu.linkonce.n.*})
. = ALIGN(2);
PROVIDE (__noinit_end = .);
}
-'
+/* This section contains data that *is* initialized during load,
+ but *not* during application reset. */
+ .persistent :
+ {
+ . = ALIGN(2);
+ PROVIDE (__persistent_start = .);
+ *(.persistent${RELOCATING+ .persistent.* .gnu.linkonce.p.*})
+ . = ALIGN(2);
+ PROVIDE (__persistent_end = .);
+ }
+"
ATTRS_SECTIONS='.ARM.attributes 0 : { KEEP (*(.ARM.attributes)) KEEP (*(.gnu.attributes)) }'
OTHER_READONLY_SECTIONS="
.ARM.extab ${RELOCATING-0} : { *(.ARM.extab${RELOCATING+* .gnu.linkonce.armextab.*}) }
new file mode 100644
@@ -0,0 +1,11 @@
+#name: .noinit and .persistent sections
+#ld: --orphan-handling=warn -e _start
+#source: noinit-sections.s
+#target: arm-*-* msp430-*-elf
+#readelf: -SW
+
+#...
+ +\[ *[0-9]+\] \.noinit +NOBITS +[0-9a-f]+ +[0-9a-f]+ [0-9a-f]+ +00 +WA .*
+#...
+ +\[ *[0-9]+\] \.persistent +PROGBITS +[0-9a-f]+ +[0-9a-f]+ [0-9a-f]+ +00 +WA .*
+#pass
new file mode 100644
@@ -0,0 +1,12 @@
+#name: .noinit and .persistent sections (ld -r)
+#ld: --orphan-handling=warn -e _start -r
+#source: noinit-sections.s
+#target: arm-*-* msp430-*-elf
+#readelf: -SW
+#warning_output: noinit-sections-2.l
+
+#...
+ +\[ *[0-9]+\] \.noinit +NOBITS +[0-9a-f]+ +[0-9a-f]+ [0-9a-f]+ +00 +WA .*
+#...
+ +\[ *[0-9]+\] \.persistent +PROGBITS +[0-9a-f]+ +[0-9a-f]+ [0-9a-f]+ +00 +WA .*
+#pass
new file mode 100644
@@ -0,0 +1,5 @@
+#...
+[^:]*: warning: orphan section `.noinit.var_noinit' from \S+ being placed in section `.noinit.var_noinit'
+#...
+[^:]*: warning: orphan section `.persistent.var_persistent' from \S+ being placed in section `.persistent.var_persistent'
+#pass
new file mode 100644
@@ -0,0 +1,16 @@
+.section .noinit,"aw",%nobits
+.word 0
+
+.section .noinit.var_noinit,"aw",%nobits
+.word 0
+
+.section .persistent,"aw"
+.word 1
+
+.section .persistent.var_persistent,"aw"
+.word 2
+
+.text
+.global _start
+_start:
+.word 0
This patch series is version 2 of https://gcc.gnu.org/pipermail/gcc-patches/2020-October/557184.html The implementation is now simplified so as to not use a symtab flag for "noinit" variables, instead we just check whether the decl has the attribute set. This patch series fixes behavior related to the "noinit" attribute, and makes the MSP430 "persistent" attribute generic, so it can be used for ARM. These attributes are related because they are both used to mark variables that should not be initialized by the target's runtime startup code. The "noinit" attribute is used for variables that are not initialized to any value by the program loader, or the runtime startup code. This attribute was made generic for GCC 10, whilst previously it was only supported for MSP430. There are a couple of issues when using it for arm-eabi: - It does not work at -O0. The test for it is in the torture directory but only runs at -O2, which is why this bug was undetected. - It does not work with -fdata-sections. Patch 1 fixes these issues. The "persistent" attribute is used for variables that *are* initialized by the program loader, but are not initialized by the runtime startup code. "persistent" variables are placed in a non-volatile area of memory, which allows their value to "persist" between processor resets. The "persistent" attribute is already implemented for msp430-elf, but patch 3 makes it generic so it can be leveraged by ARM targets. The ".persistent" section is pervasive in linker scripts distributed for ARM devices by manufacturers such as ST and TI. Patch 2 enables validation of the "persistent" attribute for when compiling C++ programs. I've attached a Binutils patch that adds the ".persistent" section to the default ARM linker script. I'll apply it alongside this GCC patch. Side note: There is handling of a ".persistent.bss" section, however this is Ada-specific and unrelated to the "noinit" and "persistent" attributes. The handling of the "noinit" and "persistent" attributes does not interfere with it. msp430-elf "persistent" attribute behaviour needs changing if this patch is approved, I have a patch ready to do that. Successfully regtested for arm-none-eabi. Ok for trunk? Jozef Lawrynowicz (3): Fix "noinit" attribute being ignored for -O0 and -fdata-sections cp/decl.c: Set DECL_INITIAL before attribute processing Implement the "persistent" attribute gcc/c-family/c-attribs.c | 141 ++++++++++++------ gcc/cp/decl.c | 13 ++ gcc/doc/extend.texi | 20 ++- .../c-c++-common/torture/attr-noinit-1.c | 7 + .../c-c++-common/torture/attr-noinit-2.c | 8 + .../c-c++-common/torture/attr-noinit-3.c | 11 ++ .../torture/attr-noinit-invalid.c | 12 ++ .../torture/attr-noinit-main.inc} | 37 ++--- .../c-c++-common/torture/attr-persistent-1.c | 8 + .../c-c++-common/torture/attr-persistent-2.c | 8 + .../c-c++-common/torture/attr-persistent-3.c | 10 ++ .../torture/attr-persistent-invalid.c | 11 ++ .../torture/attr-persistent-main.inc | 58 +++++++ .../g++.target/msp430/data-attributes.C | 52 +++++++ gcc/testsuite/g++.target/msp430/msp430.exp | 44 ++++++ .../gcc.target/msp430/data-attributes-2.c | 1 + gcc/testsuite/lib/target-supports.exp | 15 +- gcc/tree.h | 14 ++ gcc/varasm.c | 29 +++- 19 files changed, 426 insertions(+), 73 deletions(-) create mode 100644 gcc/testsuite/c-c++-common/torture/attr-noinit-1.c create mode 100644 gcc/testsuite/c-c++-common/torture/attr-noinit-2.c create mode 100644 gcc/testsuite/c-c++-common/torture/attr-noinit-3.c create mode 100644 gcc/testsuite/c-c++-common/torture/attr-noinit-invalid.c rename gcc/testsuite/{gcc.c-torture/execute/noinit-attribute.c => c-c++-common/torture/attr-noinit-main.inc} (56%) create mode 100644 gcc/testsuite/c-c++-common/torture/attr-persistent-1.c create mode 100644 gcc/testsuite/c-c++-common/torture/attr-persistent-2.c create mode 100644 gcc/testsuite/c-c++-common/torture/attr-persistent-3.c create mode 100644 gcc/testsuite/c-c++-common/torture/attr-persistent-invalid.c create mode 100644 gcc/testsuite/c-c++-common/torture/attr-persistent-main.inc create mode 100644 gcc/testsuite/g++.target/msp430/data-attributes.C create mode 100644 gcc/testsuite/g++.target/msp430/msp430.exp