Create perlstatic.h

This is used for functions that we don't suggest should be inlined, but
we think the compiler will generate better code if it has full knowledge
about them.

At the moment, it only contains a single function which can be tail-call
optimized.

The Lord of the Rings quote for this file was suggested by Leon
Timmermans.

The proximal cause of this commit can be gleaned from this email:

From - Mon Nov 16 09:20:50 2020
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Subject: Re: about commit "Revert "croak_memory_wrap is an inline function.""
 (khw)
To: bulk88 <bulk88@hotmail.com>, perl5-porters@perl.org
References: <20200429011948.14287.qmail@lists-nntp.develooper.com>
From: Karl Williamson <public@khwilliamson.com>
Message-ID: <6f38382c-8fb5-ba1a-51c6-409fa5b56d2b@khwilliamson.com>
Date: Mon, 16 Nov 2020 09:20:41 -0700
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On 4/28/20 7:19 PM, bulk88 wrote:
> https://perl5.git.perl.org/perl5.git/commitdiff/d68c938a1e6c6b4bfe907decbb4929780ee06eae
>
>
> Why was this done? Perl_croak_memory_wrap is supposed to be a static
> linkage, not globally visible C function, in every perl .o file that the
> CC/linker should toss the static func if its not used. I wanted to avoid
> the PLT/GOT runtime C symbol substitution/LDPRELOAD mechanism and let
> the CC turn Perl_croak_memory_wrap into a single conditional jump
> (offset from current instruction pointer), with no return and no C stack
> entry, jump instruction instead of
>
> call get_EIP //x86 32 only
> mov eax, *(eax_aka_eip+offset into PLT)
> call eax

I reverted this because, first of all, gcc with the appropriate -W
options raised warnings that it was disregarding the request and was not
inlining this function, and 2nd of all, there was no indication in the
comments as to why this function had been inlined.

6 files changed, 37 insertions, 11 deletions

diff --git a/MANIFEST b/MANIFEST
index 3c26c4a2b9..acf636d68c 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -5230,6 +5230,7 @@ perlio.h			PerlIO abstraction
 perlio.sym			Symbols for PerlIO abstraction
 perliol.h			PerlIO Layer definition
 perlsdio.h			Fake stdio using perlio
+perlstatic.h			Like inline.h, but functions not declared inline
 perlvars.h			Global variables
 perly.act			parser actions; derived from perly.y
 perly.c				parser code (NOT derived from perly.y)
diff --git a/embed.fnc b/embed.fnc
index 16993ae3ae..735715099f 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -2696,7 +2696,7 @@ ATdpa	|Malloc_t|safesysmalloc	|MEM_SIZE nbytes
 ATdpa	|Malloc_t|safesyscalloc	|MEM_SIZE elements|MEM_SIZE size
 ATdpR	|Malloc_t|safesysrealloc|Malloc_t where|MEM_SIZE nbytes
 AdTp	|Free_t	|safesysfree	|Malloc_t where
-CrTp	|void	|croak_memory_wrap
+CsrT	|void	|croak_memory_wrap
 Cpdh	|int	|runops_standard
 Cpdh	|int	|runops_debug
 Afpd	|void	|sv_catpvf_mg	|NN SV *const sv|NN const char *const pat|...
diff --git a/perl.h b/perl.h
index 5edc61a384..077d296065 100644
--- a/perl.h
+++ b/perl.h
@@ -7329,6 +7329,7 @@ cannot have changed since the precalculation.
 
 START_EXTERN_C
 
+#  include "perlstatic.h"
 #  include "inline.h"
 #  include "sv_inline.h"
 
diff --git a/perlstatic.h b/perlstatic.h
new file mode 100644
index 0000000000..a698de68bf
--- /dev/null
+++ b/perlstatic.h
@@ -0,0 +1,33 @@
+/*    perlstatic.h
+ *
+ *    'I don't know half of you half as well as I should like; and I like less
+ *    than half of you half as well as you deserve.'
+ *
+ *    Copyright (C) 2020 by Larry Wall and others
+ *
+ *    You may distribute under the terms of either the GNU General Public
+ *    License or the Artistic License, as specified in the README file.
+ *
+ * This file is a home for static functions that we don't consider suitable for
+ * inlining, but for which giving the compiler full knowledge of may be
+ * advantageous.  Functions that have potential tail call optimizations are a
+ * likely component.
+
+ */
+
+/* saves machine code for a common noreturn idiom typically used in Newx*() */
+GCC_DIAG_IGNORE_DECL(-Wunused-function);
+
+STATIC void
+Perl_croak_memory_wrap(void)
+{
+    Perl_croak_nocontext("%s",PL_memory_wrap);
+}
+
+GCC_DIAG_RESTORE_DECL;
+
+
+/*
+ * ex: set ts=8 sts=4 sw=4 et:
+ */
+
diff --git a/proto.h b/proto.h
index 12f9c0202c..5758c9a26c 100644
--- a/proto.h
+++ b/proto.h
@@ -776,7 +776,7 @@ PERL_CALLCONV_NO_RET void	Perl_croak_caller(const char* pat, ...)
 			__attribute__format__null_ok__(__printf__,1,2);
 #define PERL_ARGS_ASSERT_CROAK_CALLER
 
-PERL_CALLCONV_NO_RET void	Perl_croak_memory_wrap(void)
+PERL_STATIC_NO_RET void	Perl_croak_memory_wrap(void)
 			__attribute__noreturn__;
 #define PERL_ARGS_ASSERT_CROAK_MEMORY_WRAP
 
diff --git a/util.c b/util.c
index 1212a8368a..59becd4f68 100644
--- a/util.c
+++ b/util.c
@@ -2054,15 +2054,6 @@ Perl_croak_nocontext(const char *pat, ...)
 }
 #endif /* MULTIPLICITY */
 
-/* saves machine code for a common noreturn idiom typically used in Newx*() */
-GCC_DIAG_IGNORE_DECL(-Wunused-function);
-void
-Perl_croak_memory_wrap(void)
-{
-    Perl_croak_nocontext("%s",PL_memory_wrap);
-}
-GCC_DIAG_RESTORE_DECL;
-
 void
 Perl_croak(pTHX_ const char *pat, ...)
 {