On Wed, 14 Aug 2019 at 19:07, Christophe Lyon <christophe.l...@linaro.org> wrote: > > On Wed, 14 Aug 2019 at 17:59, Tamar Christina <tamar.christ...@arm.com> wrote: > > > > Hi Christoph, > > > > The noinit testcase is currently failing on x86_64. > > > > Is the test supposed to be running there? > > > No, there's an effective-target to skip it. > But I notice a typo: > +/* { dg-require-effective-target noinit */ > (missing closing brace) > Could it explain why it's failing on x86_64 ?
I fixed the typo as obvious in r274489. > > > Thanks, > > Tamar > > > > -----Original Message----- > > From: gcc-patches-ow...@gcc.gnu.org <gcc-patches-ow...@gcc.gnu.org> On > > Behalf Of Christophe Lyon > > Sent: Wednesday, August 14, 2019 2:18 PM > > To: Christophe Lyon <christophe.l...@linaro.org>; Martin Sebor > > <mse...@gmail.com>; gcc Patches <gcc-patches@gcc.gnu.org>; Richard Earnshaw > > <richard.earns...@arm.com>; ni...@redhat.com; Jozef Lawrynowicz > > <joze...@mittosystems.com>; Richard Sandiford <richard.sandif...@arm.com> > > Subject: Re: [PATCH] Add generic support for "noinit" attribute > > > > On Wed, 14 Aug 2019 at 14:14, Richard Sandiford <richard.sandif...@arm.com> > > wrote: > > > > > > Sorry for the slow response, I'd missed that there was an updated patch... > > > > > > Christophe Lyon <christophe.l...@linaro.org> writes: > > > > 2019-07-04 Christophe Lyon <christophe.l...@linaro.org> > > > > > > > > * lib/target-supports.exp (check_effective_target_noinit): New > > > > proc. > > > > * gcc.c-torture/execute/noinit-attribute.c: New test. > > > > > > Second line should be indented by tabs rather than spaces. > > > > > > > @@ -2224,6 +2234,54 @@ handle_weak_attribute (tree *node, tree name, > > > > return NULL_TREE; > > > > } > > > > > > > > +/* Handle a "noinit" attribute; arguments as in struct > > > > + attribute_spec.handler. Check whether the attribute is allowed > > > > + here and add the attribute to the variable decl tree or otherwise > > > > + issue a diagnostic. This function checks NODE is of the expected > > > > + type and issues diagnostics otherwise using NAME. If it is not of > > > > + the expected type *NO_ADD_ATTRS will be set to true. */ > > > > + > > > > +static tree > > > > +handle_noinit_attribute (tree * node, > > > > + tree name, > > > > + tree args, > > > > + int flags ATTRIBUTE_UNUSED, > > > > + bool *no_add_attrs) > > > > +{ > > > > + const char *message = NULL; > > > > + > > > > + gcc_assert (DECL_P (*node)); > > > > + gcc_assert (args == NULL); > > > > + > > > > + if (TREE_CODE (*node) != VAR_DECL) > > > > + message = G_("%qE attribute only applies to variables"); > > > > + > > > > + /* Check that it's possible for the variable to have a section. > > > > + */ else if ((TREE_STATIC (*node) || DECL_EXTERNAL (*node) || > > > > in_lto_p) > > > > + && DECL_SECTION_NAME (*node)) > > > > + message = G_("%qE attribute cannot be applied to variables " > > > > + "with specific sections"); > > > > + > > > > + if (!targetm.have_switchable_bss_sections) > > > > + message = G_("%qE attribute is specific to ELF targets"); > > > > > > Maybe make this an else if too? Or make the VAR_DECL an else if if > > > you think the ELF one should win. Either way, it seems odd to have > > > the mixture between else if and not. > > > > > Right, I changed this into an else if. > > > > > > + if (message) > > > > + { > > > > + warning (OPT_Wattributes, message, name); > > > > + *no_add_attrs = true; > > > > + } > > > > + else > > > > + /* If this var is thought to be common, then change this. Common > > > > + variables are assigned to sections before the backend has a > > > > + chance to process them. Do this only if the attribute is > > > > + valid. */ > > > > > > Comment should be indented two spaces more. > > > > > > > + if (DECL_COMMON (*node)) > > > > + DECL_COMMON (*node) = 0; > > > > + > > > > + return NULL_TREE; > > > > +} > > > > + > > > > + > > > > /* Handle a "noplt" attribute; arguments as in > > > > struct attribute_spec.handler. */ > > > > > > > > diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index > > > > f2619e1..f1af1dc 100644 > > > > --- a/gcc/doc/extend.texi > > > > +++ b/gcc/doc/extend.texi > > > > @@ -7129,6 +7129,14 @@ The @code{visibility} attribute is described > > > > in The @code{weak} attribute is described in @ref{Common Function > > > > Attributes}. > > > > > > > > +@item noinit > > > > +@cindex @code{noinit} variable attribute Any data with the > > > > +@code{noinit} attribute will not be initialized by the C runtime > > > > +startup code, or the program loader. Not initializing data in this > > > > +way can reduce program startup times. Specific to ELF targets, > > > > +this attribute relies on the linker to place such data in the right > > > > +location. > > > > > > Maybe: > > > > > > This attribute is specific to ELF targets and relies on the linker to > > > place such data in the right location. > > > > > Thanks, I thought I had chosen a nice turn of phrase :-) > > > > > > > > diff --git a/gcc/testsuite/gcc.c-torture/execute/noinit-attribute.c > > > > b/gcc/testsuite/gcc.c-torture/execute/noinit-attribute.c > > > > new file mode 100644 > > > > index 0000000..ffcf8c6 > > > > --- /dev/null > > > > +++ b/gcc/testsuite/gcc.c-torture/execute/noinit-attribute.c > > > > @@ -0,0 +1,59 @@ > > > > +/* { dg-do run } */ > > > > +/* { dg-require-effective-target noinit */ > > > > +/* { dg-options "-O2" } */ > > > > + > > > > +/* This test checks that noinit data is handled correctly. */ > > > > + > > > > +extern void _start (void) __attribute__ ((noreturn)); extern void > > > > +abort (void) __attribute__ ((noreturn)); extern void exit (int) > > > > +__attribute__ ((noreturn)); > > > > + > > > > +int var_common; > > > > +int var_zero = 0; > > > > +int var_one = 1; > > > > +int __attribute__((noinit)) var_noinit; int var_init = 2; > > > > + > > > > +int __attribute__((noinit)) func(); /* { dg-warning "attribute only > > > > +applies to variables" } */ int __attribute__((section > > > > +("mysection"), noinit)) var_section1; /* { dg-warning "because it > > > > +conflicts with attribute" } */ int __attribute__((noinit, section > > > > +("mysection"))) var_section2; /* { dg-warning "because it conflicts > > > > +with attribute" } */ > > > > + > > > > + > > > > +int > > > > +main (void) > > > > +{ > > > > + /* Make sure that the C startup code has correctly initialized > > > > +the ordinary variables. */ > > > > + if (var_common != 0) > > > > + abort (); > > > > + > > > > + /* Initialized variables are not re-initialized during startup, so > > > > + check their original values only during the first run of this > > > > + test. */ > > > > + if (var_init == 2) > > > > + if (var_zero != 0 || var_one != 1) > > > > + abort (); > > > > + > > > > + switch (var_init) > > > > + { > > > > + case 2: > > > > + /* First time through - change all the values. */ > > > > + var_common = var_zero = var_one = var_noinit = var_init = 3; > > > > + break; > > > > + > > > > + case 3: > > > > + /* Second time through - make sure that d has not been reset. */ > > > > + if (var_noinit != 3) > > > > + abort (); > > > > + exit (0); > > > > + > > > > + default: > > > > + /* Any other value for var_init is an error. */ > > > > + abort (); > > > > + } > > > > + > > > > + /* Simulate a processor reset by calling the C startup code. */ > > > > + _start (); > > > > + > > > > + /* Should never reach here. */ > > > > + abort (); > > > > +} > > > > diff --git a/gcc/testsuite/lib/target-supports.exp > > > > b/gcc/testsuite/lib/target-supports.exp > > > > index 815e837..ae05c0a 100644 > > > > --- a/gcc/testsuite/lib/target-supports.exp > > > > +++ b/gcc/testsuite/lib/target-supports.exp > > > > @@ -364,6 +364,18 @@ proc check_weak_override_available { } { > > > > return [check_weak_available] > > > > } > > > > > > > > +# 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 { } { > > > > + if { [istarget arm*-*-eabi] > > > > + || [istarget msp430-*-*] } { > > > > + return 1 > > > > + } > > > > + > > > > + return 0 > > > > +} > > > > + > > > > ############################### > > > > # proc check_visibility_available { what_kind } > > > > ############################### diff --git a/gcc/varasm.c > > > > b/gcc/varasm.c index 626a4c9..6ddab0ce 100644 > > > > --- a/gcc/varasm.c > > > > +++ b/gcc/varasm.c > > > > @@ -6428,6 +6428,9 @@ default_section_type_flags (tree decl, const char > > > > *name, int reloc) > > > > || strncmp (name, ".gnu.linkonce.tb.", 17) == 0) > > > > flags |= SECTION_TLS | SECTION_BSS; > > > > > > > > + if (strcmp (name, ".noinit") == 0) > > > > + flags |= SECTION_WRITE | SECTION_BSS | SECTION_NOTYPE; > > > > + > > > > /* Various sections have special ELF types that the assembler will > > > > assign by default based on the name. They are neither > > > > SHT_PROGBITS > > > > nor SHT_NOBITS, so when changing sections we don't want to > > > > print a @@ -6748,11 +6751,14 @@ decl_readonly_section (const_tree > > > > decl, int reloc) > > > > > > > > /* Select a section based on the above categorization. */ > > > > > > > > +static section *noinit_section = NULL; > > > > + > > > > > > No longer needed. > > Indeed. > > > > > > > > OK with those changes, thanks. > > Thanks, committed as r274482. > > > > Christophe > > > > > Richard > > > > > > > section * > > > > default_elf_select_section (tree decl, int reloc, > > > > unsigned HOST_WIDE_INT align) { > > > > const char *sname; > > > > + > > > > switch (categorize_decl_for_section (decl, reloc)) > > > > { > > > > case SECCAT_TEXT: > > > > @@ -6790,6 +6796,13 @@ 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) > > > > + { > > > > + sname = ".noinit"; > > > > + break; > > > > + } > > > > + > > > > if (bss_section) > > > > return bss_section; > > > > sname = ".bss";