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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: no code generation for c strings
Date: Fri, 03 Jun 2016 17:30:12 +0100
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Date: 2016-06-03T17:30:12+01:00
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> On 03/06/2016 10:14, Luke A. Guest wrote:
>
>> What I would like to have is have the compiler recognise that I've declared
>> a static char_array and just not generate a call to the secondary stack to
>> allocate a new string. Is this actually possible? -O2/3 still generate the
>> call.
>>
>> S : constant char_array := to_c ("hello" & nul);
>
> S : constant char_array := "hello" & char'val (0);

GCC 6.1.0:

   with Interfaces.C;
   package Char_Arrays is
      use type Interfaces.C.char;
      use type Interfaces.C.char_array;
      S : constant Interfaces.C.char_array :=
        "hello" & Interfaces.C.char'Val (0);
   end Char_Arrays;

generates (x86_64-apple-darwin15)

	.globl _char_arrays__s
	.const
	.align 3
_char_arrays__s:
	.ascii "hello\0"
	.space 2
	.globl _char_arrays_E
	.data
	.align 1
_char_arrays_E:
	.space 2
	.subsections_via_symbols

& similar for arm-eabi.