On Wed, Dec 3, 2014 at 7:01 AM, H.J. Lu <hjl.to...@gmail.com> wrote:
> On Wed, Dec 3, 2014 at 5:47 AM, H.J. Lu <hjl.to...@gmail.com> wrote:
>> On Tue, Dec 2, 2014 at 12:01 PM, Uros Bizjak <ubiz...@gmail.com> wrote:
>>> On Tue, Dec 2, 2014 at 8:40 PM, H.J. Lu <hjl.to...@gmail.com> wrote:
>>>> On Tue, Dec 2, 2014 at 11:19 AM, Uros Bizjak <ubiz...@gmail.com> wrote:
>>>>> Hello!
>>>>>
>>>>>> Ping.
>>>>>>> Ping.
>>>>>>>> Ping.
>>>>>>>>> Ping.
>>>>>
>>>>> It would probably help reviewers if you pointed to actual path
>>>>> submission [1], which unfortunately contains the explanation in the
>>>>> patch itself [2], which further explains that this functionality is
>>>>> currently only supported with gold, patched with [3].
>>>>>
>>>>> [1] https://gcc.gnu.org/ml/gcc-patches/2014-09/msg00645.html
>>>>> [2] https://gcc.gnu.org/ml/gcc-patches/2014-09/txt2CHtu81P1O.txt
>>>>> [3] https://sourceware.org/ml/binutils/2014-05/msg00092.html
>>>>>
>>>>> After a bit of the above detective work, I think that new gcc option
>>>>> is not necessary. The configure should detect if new functionality is
>>>>> supported in the linker, and auto-configure gcc to use it when
>>>>> appropriate.
>>>>
>>>> I think GCC option is needed since one can use -fuse-ld= to
>>>> change linker.
>>>
>>> IMO, nobody will use this highly special x86_64-only option. It would
>>> be best for gnu-ld to reach feature parity with gold as far as this
>>> functionality is concerned. In this case, the optimization would be
>>> auto-configured, and would fire automatically, without any user
>>> intervention.
>>>
>>
>> Let's do it. I implemented the same feature in bfd linker on both
>> master and 2.25 branch.
>>
>
> +bool
> +i386_binds_local_p (const_tree exp)
> +{
> + /* Globals marked extern are treated as local when linker copy relocations
> + support is available with -f{pie|PIE}. */
> + if (TARGET_64BIT && ix86_copyrelocs && flag_pie
> + && TREE_CODE (exp) == VAR_DECL
> + && DECL_EXTERNAL (exp) && !DECL_WEAK (exp))
> + return true;
> + return default_binds_local_p (exp);
> +}
> +
>
> It returns true with -fPIE and false without -fPIE. It is lying to compiler.
> Maybe legitimate_pic_address_disp_p is a better place.
>
Something like this?
--
H.J.
diff --git a/gcc/config.in b/gcc/config.in
index 65d5e42..f34adb5 100644
--- a/gcc/config.in
+++ b/gcc/config.in
@@ -1411,6 +1411,12 @@
#endif
+/* Define 0/1 if your linker supports -pie option with copy reloc. */
+#ifndef USED_FOR_TARGET
+#undef HAVE_LD_PIE_COPYRELOC
+#endif
+
+
/* Define if your linker links a mix of read-only and read-write sections into
a read-write section. */
#ifndef USED_FOR_TARGET
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 211c9e6..eb43bc6 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -13113,7 +13113,10 @@ legitimate_pic_address_disp_p (rtx disp)
return true;
}
else if (!SYMBOL_REF_FAR_ADDR_P (op0)
- && SYMBOL_REF_LOCAL_P (op0)
+ && (SYMBOL_REF_LOCAL_P (op0)
+ || (HAVE_LD_PIE_COPYRELOC
+ && flag_pie
+ && !SYMBOL_REF_FUNCTION_P (op0)))
&& ix86_cmodel != CM_LARGE_PIC)
return true;
break;
diff --git a/gcc/configure b/gcc/configure
index 6b46bbb..811f05d 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -27025,6 +27025,53 @@ fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_ld_pie" >&5
$as_echo "$gcc_cv_ld_pie" >&6; }
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking linker PIE support with copy reloc" >&5
+$as_echo_n "checking linker PIE support with copy reloc... " >&6; }
+gcc_cv_ld_pie_copyreloc=no
+if test $gcc_cv_ld_pie = yes ; then
+ if test $in_tree_ld = yes ; then
+ if test "$gcc_cv_gld_major_version" -eq 2 -a "$gcc_cv_gld_minor_version" -ge 25 -o "$gcc_cv_gld_major_version" -gt 2; then
+ gcc_cv_ld_pie_copyreloc=yes
+ fi
+ elif test x$gcc_cv_as != x -a x$gcc_cv_ld != x ; then
+ # Check if linker supports -pie option with copy reloc
+ case "$target" in
+ i?86-*-linux* | x86_64-*-linux*)
+ cat > conftest1.s <<EOF
+ .globl a_glob
+ .data
+ .type a_glob, @object
+ .size a_glob, 4
+a_glob:
+ .long 2
+EOF
+ cat > conftest2.s <<EOF
+ .text
+ .globl main
+ .type main, @function
+main:
+ movl %eax, a_glob(%rip)
+ .size main, .-main
+EOF
+ if $gcc_cv_as --64 -o conftest1.o conftest1.s > /dev/null 2>&1 \
+ && $gcc_cv_ld -shared -melf_x86_64 -o conftest1.so conftest1.o > /dev/null 2>&1 \
+ && $gcc_cv_as --64 -o conftest2.o conftest2.s > /dev/null 2>&1 \
+ && $gcc_cv_ld -pie -melf_x86_64 -o conftest conftest2.o conftest1.so > /dev/null 2>&1; then
+ gcc_cv_ld_pie_copyreloc=yes
+ fi
+ rm -f conftest conftest1.so conftest1.o conftest2.o conftest1.s conftest2.s
+ ;;
+ esac
+ fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_LD_PIE_COPYRELOC `if test x"$gcc_cv_ld_pie_copyreloc" = xyes; then echo 1; else echo 0; fi`
+_ACEOF
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_ld_pie_copyreloc" >&5
+$as_echo "$gcc_cv_ld_pie_copyreloc" >&6; }
+
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking linker EH-compatible garbage collection of sections" >&5
$as_echo_n "checking linker EH-compatible garbage collection of sections... " >&6; }
gcc_cv_ld_eh_gc_sections=no
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 48c8000..a33f3a5 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -4693,6 +4693,49 @@ if test x"$gcc_cv_ld_pie" = xyes; then
fi
AC_MSG_RESULT($gcc_cv_ld_pie)
+AC_MSG_CHECKING(linker PIE support with copy reloc)
+gcc_cv_ld_pie_copyreloc=no
+if test $gcc_cv_ld_pie = yes ; then
+ if test $in_tree_ld = yes ; then
+ if test "$gcc_cv_gld_major_version" -eq 2 -a "$gcc_cv_gld_minor_version" -ge 25 -o "$gcc_cv_gld_major_version" -gt 2; then
+ gcc_cv_ld_pie_copyreloc=yes
+ fi
+ elif test x$gcc_cv_as != x -a x$gcc_cv_ld != x ; then
+ # Check if linker supports -pie option with copy reloc
+ case "$target" in
+ i?86-*-linux* | x86_64-*-linux*)
+ cat > conftest1.s <<EOF
+ .globl a_glob
+ .data
+ .type a_glob, @object
+ .size a_glob, 4
+a_glob:
+ .long 2
+EOF
+ cat > conftest2.s <<EOF
+ .text
+ .globl main
+ .type main, @function
+main:
+ movl %eax, a_glob(%rip)
+ .size main, .-main
+EOF
+ if $gcc_cv_as --64 -o conftest1.o conftest1.s > /dev/null 2>&1 \
+ && $gcc_cv_ld -shared -melf_x86_64 -o conftest1.so conftest1.o > /dev/null 2>&1 \
+ && $gcc_cv_as --64 -o conftest2.o conftest2.s > /dev/null 2>&1 \
+ && $gcc_cv_ld -pie -melf_x86_64 -o conftest conftest2.o conftest1.so > /dev/null 2>&1; then
+ gcc_cv_ld_pie_copyreloc=yes
+ fi
+ rm -f conftest conftest1.so conftest1.o conftest2.o conftest1.s conftest2.s
+ ;;
+ esac
+ fi
+ AC_DEFINE_UNQUOTED(HAVE_LD_PIE_COPYRELOC,
+ [`if test x"$gcc_cv_ld_pie_copyreloc" = xyes; then echo 1; else echo 0; fi`],
+ [Define 0/1 if your linker supports -pie option with copy reloc.])
+fi
+AC_MSG_RESULT($gcc_cv_ld_pie_copyreloc)
+
AC_MSG_CHECKING(linker EH-compatible garbage collection of sections)
gcc_cv_ld_eh_gc_sections=no
if test $in_tree_ld = yes ; then
