On Sat, Jan 18, 2020 at 1:30 PM Jakub Jelinek <ja...@redhat.com> wrote:
>
> Hi!
>
> In AT&T syntax leading $ is special, so if we have identifiers that start
> with dollar, we usually fail to assemble it (or assemble incorrectly).
> As mentioned in the PR, what works is wrapping the identifiers inside of
> parens, like:
> movl $($a), %eax
> leaq ($a)(,%rdi,4), %rax
> movl ($a)(%rip), %eax
> movl ($a)+16(%rip), %eax
> .globl $a
> .type $a, @object
> .size $a, 72
> $a:
> .string "$a"
> .quad ($a)
> (this is x86_64 -fno-pic -O2). In some places ($a) is not accepted,
> like as .globl operand, in .type, .size, so the patch overrides
> ASM_OUTPUT_SYMBOL_REF rather than e.g. ASM_OUTPUT_LABELREF.
> I didn't want to duplicate what assemble_name is doing (following
> transparent aliases), so split assemble_name into two parts; just
> mere looking at the first character of a name before calling assemble_name
> wouldn't be good enough, a transparent alias could lead from a name
> not starting with $ to one starting with it and vice versa.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2020-01-18 Jakub Jelinek <ja...@redhat.com>
>
> PR target/91298
> * output.h (assemble_name_resolve): Declare.
> * varasm.c (assemble_name_resolve): New function.
> (assemble_name): Use it.
> * config/i386/i386.h (ASM_OUTPUT_SYMBOL_REF): Define.
>
> * gcc.target/i386/pr91298-1.c: New test.
> * gcc.target/i386/pr91298-2.c: New test.
x86 part is OK, with a nit below.
Thanks,
Uros.
> --- gcc/output.h.jj 2020-01-12 11:54:36.692409199 +0100
> +++ gcc/output.h 2020-01-17 09:51:27.606873017 +0100
> @@ -237,6 +237,12 @@ extern void assemble_label (FILE *, cons
> addition of an underscore). */
> extern void assemble_name_raw (FILE *, const char *);
>
> +/* Return NAME that should actually be emitted, looking through
> + transparent aliases. If NAME refers to an entity that is also
> + represented as a tree (like a function or variable), mark the entity
> + as referenced. */
> +extern const char *assemble_name_resolve (const char *);
> +
> /* Like assemble_name_raw, but should be used when NAME might refer to
> an entity that is also represented as a tree (like a function or
> variable). If NAME does refer to such an entity, that entity will
> --- gcc/varasm.c.jj 2020-01-12 11:54:38.533381424 +0100
> +++ gcc/varasm.c 2020-01-17 09:53:14.430239885 +0100
> @@ -2589,20 +2589,16 @@ assemble_name_raw (FILE *file, const cha
> ASM_OUTPUT_LABELREF (file, name);
> }
>
> -/* Like assemble_name_raw, but should be used when NAME might refer to
> - an entity that is also represented as a tree (like a function or
> - variable). If NAME does refer to such an entity, that entity will
> - be marked as referenced. */
> -
> -void
> -assemble_name (FILE *file, const char *name)
> +/* Return NAME that should actually be emitted, looking through
> + transparent aliases. If NAME refers to an entity that is also
> + represented as a tree (like a function or variable), mark the entity
> + as referenced. */
> +const char *
> +assemble_name_resolve (const char *name)
> {
> - const char *real_name;
> - tree id;
> + const char *real_name = targetm.strip_name_encoding (name);
> + tree id = maybe_get_identifier (real_name);
>
> - real_name = targetm.strip_name_encoding (name);
> -
> - id = maybe_get_identifier (real_name);
> if (id)
> {
> tree id_orig = id;
> @@ -2614,7 +2610,18 @@ assemble_name (FILE *file, const char *n
> gcc_assert (! TREE_CHAIN (id));
> }
>
> - assemble_name_raw (file, name);
> + return name;
> +}
> +
> +/* Like assemble_name_raw, but should be used when NAME might refer to
> + an entity that is also represented as a tree (like a function or
> + variable). If NAME does refer to such an entity, that entity will
> + be marked as referenced. */
> +
> +void
> +assemble_name (FILE *file, const char *name)
> +{
> + assemble_name_raw (file, assemble_name_resolve (name));
> }
>
> /* Allocate SIZE bytes writable static space with a gensym name
> --- gcc/config/i386/i386.h.jj 2020-01-17 09:22:47.524148012 +0100
> +++ gcc/config/i386/i386.h 2020-01-17 10:21:10.822480641 +0100
> @@ -2258,6 +2258,31 @@ extern int const svr4_dbx_register_map[F
> #define ASM_OUTPUT_FUNCTION_LABEL(FILE, NAME, DECL) \
> ix86_asm_output_function_label ((FILE), (NAME), (DECL))
>
> +/* A C statement (sans semicolon) to output a reference to SYMBOL_REF SYM.
> + If not defined, assemble_name will be used to output the name of the
> + symbol. This macro may be used to modify the way a symbol is referenced
> + depending on information encoded by TARGET_ENCODE_SECTION_INFO. */
> +
> +#ifndef ASM_OUTPUT_SYMBOL_REF
> +#define ASM_OUTPUT_SYMBOL_REF(FILE, SYM) \
> + do { \
> + const char *name \
> + = assemble_name_resolve (XSTR (x, 0)); \
> + /* In -masm=att wrap identifiers that start with $ \
> + into parens. */ \
> + if (name[0] == '$' \
> + && user_label_prefix[0] == '\0' \
> + && ASSEMBLER_DIALECT == ASM_ATT) \
I'd putthe check for assembler dialect first, it looks more descriptive.
> + { \
> + fputc ('(', (FILE)); \
> + assemble_name_raw ((FILE), name); \
> + fputc (')', (FILE)); \
> + } \
> + else \
> + assemble_name_raw ((FILE), name); \
> + } while (0)
> +#endif
> +
> /* Under some conditions we need jump tables in the text section,
> because the assembler cannot handle label differences between
> sections. This is the case for x86_64 on Mach-O for example. */
> --- gcc/testsuite/gcc.target/i386/pr91298-1.c.jj 2020-01-17
> 10:45:24.172222204 +0100
> +++ gcc/testsuite/gcc.target/i386/pr91298-1.c 2020-01-17 10:44:46.388800409
> +0100
> @@ -0,0 +1,14 @@
> +/* PR target/91298 */
> +/* { dg-do assemble } */
> +/* { dg-options "-O2 -g -fdollars-in-identifiers" } */
> +
> +int $a[18];
> +int *foo (void) { return &$a[0]; }
> +int *bar (int x) { return &$a[x]; }
> +int baz (void) { return $a[0]; }
> +int qux (void) { return $a[4]; }
> +int $quux (void) { return 1; }
> +int corge (void) { return $quux (); }
> +int grault (void) { return $quux () + 1; }
> +typedef int (*fn) (void);
> +fn foobar (void) { return $quux; }
> --- gcc/testsuite/gcc.target/i386/pr91298-2.c.jj 2020-01-17
> 10:45:30.834120262 +0100
> +++ gcc/testsuite/gcc.target/i386/pr91298-2.c 2020-01-17 10:45:57.460712790
> +0100
> @@ -0,0 +1,5 @@
> +/* PR target/91298 */
> +/* { dg-do assemble { target fpic } } */
> +/* { dg-options "-O2 -g -fdollars-in-identifiers -fpic" } */
> +
> +#include "pr91298-1.c"
>
> Jakub
>
