components/developer/gcc-10/patches/0006-allow-the-global-disabling-of-function-cloning.patch

   1 From 737d79516ecaa1ccb1ad43e25006e2129c44ff8d Mon Sep 17 00:00:00 2001
   2 From: Richard Lowe <richlowe@richlowe.net>
   3 Date: Sun, 30 Sep 2012 16:44:14 -0400
   4 Subject: [PATCH 06/34] allow the global disabling of function cloning
   5
   6 Optimizations which clone functions to create call-specific implementations
   7 which may be better optimized also dissociate these functions from their
   8 symbol names in ways harmful to tracing and debugging (since there are now
   9 several implementations of a single source symbol, quite possibly none of them
  10 having the actual source symbol name).
  11
  12 This allows any function cloning to be disabled, and makes any such
  13 optimization ineffective, and our source safe for debuggers everywhere.
  14 ---
  15  gcc/attribs.c       |  9 +++++++++
  16  gcc/common.opt      |  5 +++++
  17  gcc/doc/invoke.texi | 10 ++++++++++
  18  3 files changed, 24 insertions(+)
  19
  20 diff --git a/gcc/attribs.c b/gcc/attribs.c
  21 index 7d0f4b5b7b4..2d8f34d371a 100644
  22 --- a/gcc/attribs.c
  23 +++ b/gcc/attribs.c
  24 @@ -543,6 +543,15 @@ decl_attributes (tree *node, tree attributes, int flags,
  25         attributes = tree_cons (get_identifier ("no_icf"),  NULL, attributes);
  26      }
  27
  28 +  /* If the user passed -fno-clone-functions, all functions should be treated
  29 +     as "noclone" */
  30 +  if (TREE_CODE (*node) == FUNCTION_DECL
  31 +      && !flag_clone_functions)
  32 +    {
  33 +      if (lookup_attribute ("noclone", attributes) == NULL)
  34 +       attributes = tree_cons (get_identifier ("noclone"),  NULL, attributes);
  35 +    }
  36 +
  37    targetm.insert_attributes (*node, &attributes);
  38
  39    /* Note that attributes on the same declaration are not necessarily
  40 diff --git a/gcc/common.opt b/gcc/common.opt
  41 index 561e7af9783..a2e214337f0 100644
  42 --- a/gcc/common.opt
  43 +++ b/gcc/common.opt
  44 @@ -1145,6 +1145,11 @@ fcode-hoisting
  45  Common Report Var(flag_code_hoisting) Optimization
  46  Enable code hoisting.
  47
  48 +fclone-functions
  49 +Common Report Var(flag_clone_functions) Init(1)
  50 +Allow the compiler to clone functions to facilitate certain optimizations.
  51 +Enabled by default.
  52 +
  53  fcombine-stack-adjustments
  54  Common Report Var(flag_combine_stack_adjustments) Optimization
  55  Looks for opportunities to reduce stack adjustments and stack references.
  56 diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
  57 index 7d863e6a083..e8ec1ae4ea4 100644
  58 --- a/gcc/doc/invoke.texi
  59 +++ b/gcc/doc/invoke.texi
  60 @@ -461,6 +461,7 @@ Objective-C and Objective-C++ Dialects}.
  61  -fassociative-math  -fauto-profile  -fauto-profile[=@var{path}] @gol
  62  -fauto-inc-dec  -fbranch-probabilities @gol
  63  -fcaller-saves @gol
  64 +-fclone-functions
  65  -fcombine-stack-adjustments  -fconserve-stack @gol
  66  -fcompare-elim  -fcprop-registers  -fcrossjumping @gol
  67  -fcse-follow-jumps  -fcse-skip-blocks  -fcx-fortran-rules @gol
  68 @@ -10134,6 +10135,15 @@ and then tries to find ways to combine them.
  69
  70  Enabled by default at @option{-O1} and higher.
  71
  72 +@item -fno-clone-functions
  73 +@opindex fno-clone-functions
  74 +Forbid the implicit cloning of functions implicit in certain
  75 +optimizations.  This also effectively will disable any optimization
  76 +which wishes to clone functions, equivalent to each function having
  77 +the ``noclone'' attribute.  This allows the prevention of the
  78 +dissociation of a piece of text from an intelligible and expected
  79 +symbol name, which may hamper debugging and tracing.
  80 +
  81  @item -fipa-ra
  82  @opindex fipa-ra
  83  Use caller save registers for allocation if those registers are not used by
  84 --
  85 2.31.1
  86