From 737d79516ecaa1ccb1ad43e25006e2129c44ff8d Mon Sep 17 00:00:00 2001
From: Richard Lowe <richlowe@richlowe.net>
Date: Sun, 30 Sep 2012 16:44:14 -0400
Subject: [PATCH 06/34] allow the global disabling of function cloning
Optimizations which clone functions to create call-specific implementations
which may be better optimized also dissociate these functions from their
symbol names in ways harmful to tracing and debugging (since there are now
several implementations of a single source symbol, quite possibly none of them
having the actual source symbol name).
This allows any function cloning to be disabled, and makes any such
optimization ineffective, and our source safe for debuggers everywhere.
---
gcc/attribs.c | 9 +++++++++
gcc/common.opt | 5 +++++
gcc/doc/invoke.texi | 10 ++++++++++
3 files changed, 24 insertions(+)
diff --git a/gcc/attribs.c b/gcc/attribs.c
index 7d0f4b5b7b4..2d8f34d371a 100644
--- a/gcc/attribs.c
+++ b/gcc/attribs.c
@@ -543,6 +543,15 @@ decl_attributes (tree *node, tree attributes, int flags,
attributes = tree_cons (get_identifier ("no_icf"), NULL, attributes);
}
+ /* If the user passed -fno-clone-functions, all functions should be treated
+ as "noclone" */
+ if (TREE_CODE (*node) == FUNCTION_DECL
+ && !flag_clone_functions)
+ {
+ if (lookup_attribute ("noclone", attributes) == NULL)
+ attributes = tree_cons (get_identifier ("noclone"), NULL, attributes);
+ }
+
targetm.insert_attributes (*node, &attributes);
/* Note that attributes on the same declaration are not necessarily
diff --git a/gcc/common.opt b/gcc/common.opt
index 561e7af9783..a2e214337f0 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1145,6 +1145,11 @@ fcode-hoisting
Common Report Var(flag_code_hoisting) Optimization
Enable code hoisting.
+fclone-functions
+Common Report Var(flag_clone_functions) Init(1)
+Allow the compiler to clone functions to facilitate certain optimizations.
+Enabled by default.
+
fcombine-stack-adjustments
Common Report Var(flag_combine_stack_adjustments) Optimization
Looks for opportunities to reduce stack adjustments and stack references.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 7d863e6a083..e8ec1ae4ea4 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -461,6 +461,7 @@ Objective-C and Objective-C++ Dialects}.
-fassociative-math -fauto-profile -fauto-profile[=@var{path}] @gol
-fauto-inc-dec -fbranch-probabilities @gol
-fcaller-saves @gol
+-fclone-functions
-fcombine-stack-adjustments -fconserve-stack @gol
-fcompare-elim -fcprop-registers -fcrossjumping @gol
-fcse-follow-jumps -fcse-skip-blocks -fcx-fortran-rules @gol
@@ -10134,6 +10135,15 @@ and then tries to find ways to combine them.
Enabled by default at @option{-O1} and higher.
+@item -fno-clone-functions
+@opindex fno-clone-functions
+Forbid the implicit cloning of functions implicit in certain
+optimizations. This also effectively will disable any optimization
+which wishes to clone functions, equivalent to each function having
+the ``noclone'' attribute. This allows the prevention of the
+dissociation of a piece of text from an intelligible and expected
+symbol name, which may hamper debugging and tracing.
+
@item -fipa-ra
@opindex fipa-ra
Use caller save registers for allocation if those registers are not used by
--
2.31.1