Re: [PATCH] Extend -fno-plt to normal non-PIC branches on x86
On Fri, May 29, 2015 at 1:02 AM, H.J. Lu wrote: > On Thu, May 28, 2015 at 10:37:53AM -0700, H.J. Lu wrote: >> This patch extends -fno-plt to normal non-PIC calls on x86. -fno-plt >> works in 64-bit mode with the existing binutils. For 32-bit, we need >> the updated assembler and linker to support "call/jmp *foo@GOT" with >> a new relocation different from R_386_GOT32 to indicate that this >> relocation applies to indirect branches. A configure time check is >> added to verify that 32-bit assembler generates a known relocation >> which is different from R_386_GOT32. A new 32-bit relocaton is needed >> since "call/jmp *foo@GOT" requires a different relocation from R_386_GOT32 >> which is used together with a GOT register in "call/jmp *foo@GOT(%reg)". >> >> OK for master? >> >> Thanks. >> >> H.J. >> --- >> * configure.ac (HAVE_AS_INDIRECT_BRANCH_VIA_GOT): New. Defined >> if 32-bit assembler generates a known relocation which is >> different from R_386_GOT32. >> * config.in: Regenerated. >> * configure: Likewise. >> * config/i386/i386.c (ix86_output_call_insn): Extend -fno-plt >> to normal non-PIC branches. > > > Here is the updated patch to properly handle local functions with > testcases. Please get someone to review the functional aspect of the patch. I'm not that familiar with all linker details to do any meaningful review here. Uros.
Re: [PATCH] Extend -fno-plt to normal non-PIC branches on x86
On Thu, May 28, 2015 at 10:37:53AM -0700, H.J. Lu wrote:
> This patch extends -fno-plt to normal non-PIC calls on x86. -fno-plt
> works in 64-bit mode with the existing binutils. For 32-bit, we need
> the updated assembler and linker to support "call/jmp *foo@GOT" with
> a new relocation different from R_386_GOT32 to indicate that this
> relocation applies to indirect branches. A configure time check is
> added to verify that 32-bit assembler generates a known relocation
> which is different from R_386_GOT32. A new 32-bit relocaton is needed
> since "call/jmp *foo@GOT" requires a different relocation from R_386_GOT32
> which is used together with a GOT register in "call/jmp *foo@GOT(%reg)".
>
> OK for master?
>
> Thanks.
>
> H.J.
> ---
> * configure.ac (HAVE_AS_INDIRECT_BRANCH_VIA_GOT): New. Defined
> if 32-bit assembler generates a known relocation which is
> different from R_386_GOT32.
> * config.in: Regenerated.
> * configure: Likewise.
> * config/i386/i386.c (ix86_output_call_insn): Extend -fno-plt
> to normal non-PIC branches.
Here is the updated patch to properly handle local functions with
testcases.
H.J.
---
gcc/
* configure.ac (HAVE_AS_INDIRECT_BRANCH_VIA_GOT): New. Defined
if 32-bit assembler generates a known relocation which is
different from R_386_GOT32.
* config.in: Regenerated.
* configure: Likewise.
* config/i386/i386.c (ix86_output_call_insn): Extend -fno-plt
to normal non-PIC branches.
* config/i386/i386.h (TARGET_ELF): New.
gcc/testsuite/
* gcc.target/i386/pr66232-6.c: New tests.
* gcc.target/i386/pr66232-7.c: Likewise.
* gcc.target/i386/pr66232-8.c: Likewise.
* gcc.target/i386/pr66232-9.c: Likewise.
* gcc.target/i386/pr66232-10.c: Likewise.
* gcc.target/i386/pr66232-11.c: Likewise.
* gcc.target/i386/pr66232-12.c: Likewise.
* gcc.target/i386/pr66232-13.c: Likewise.
* lib/target-supports.exp (check_effective_target_branch_via_got):
New.
---
gcc/config.in | 14 +---
gcc/config/i386/i386.c | 40 +--
gcc/config/i386/i386.h | 2 ++
gcc/configure | 47 ++-
gcc/configure.ac | 18 ++-
gcc/testsuite/gcc.target/i386/pr66232-10.c | 13
gcc/testsuite/gcc.target/i386/pr66232-11.c | 14
gcc/testsuite/gcc.target/i386/pr66232-12.c | 13
gcc/testsuite/gcc.target/i386/pr66232-13.c | 13
gcc/testsuite/gcc.target/i386/pr66232-6.c | 13
gcc/testsuite/gcc.target/i386/pr66232-7.c | 14
gcc/testsuite/gcc.target/i386/pr66232-8.c | 13
gcc/testsuite/gcc.target/i386/pr66232-9.c | 13
gcc/testsuite/lib/target-supports.exp | 52 ++
14 files changed, 271 insertions(+), 8 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/i386/pr66232-10.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr66232-11.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr66232-12.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr66232-13.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr66232-6.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr66232-7.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr66232-8.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr66232-9.c
diff --git a/gcc/config.in b/gcc/config.in
index daaf906..0ee5c38 100644
--- a/gcc/config.in
+++ b/gcc/config.in
@@ -363,6 +363,12 @@
#endif
+/* Define true if the assembler supports 'call *foo@GOT'. */
+#ifndef USED_FOR_TARGET
+#undef HAVE_AS_INDIRECT_BRANCH_VIA_GOT
+#endif
+
+
/* Define if your assembler supports the Sun syntax for cmov. */
#ifndef USED_FOR_TARGET
#undef HAVE_AS_IX86_CMOV_SUN_SYNTAX
@@ -686,8 +692,8 @@
#endif
-/* Define to 1 if we found a declaration for 'basename', otherwise define to
- 0. */
+/* Define to 1 if you have the declaration of `basename(const char*)', and to
+ 0 if you don't. */
#ifndef USED_FOR_TARGET
#undef HAVE_DECL_BASENAME
#endif
@@ -963,8 +969,8 @@
#endif
-/* Define to 1 if we found a declaration for 'strstr', otherwise define to 0.
- */
+/* Define to 1 if you have the declaration of `strstr(const char*,const
+ char*)', and to 0 if you don't. */
#ifndef USED_FOR_TARGET
#undef HAVE_DECL_STRSTR
#endif
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index e77cd04..63ebc7f 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -25611,7 +25611,25 @@ ix86_output_call_insn (rtx_insn *insn, rtx call_op)
if (SIBLING_CALL_P (insn))
{
if (direct_p)
- xasm = "%!jmp\t%P0";
+ {
+ if (!SYMBOL_REF_LOCAL_P (call_op)
+ && !flag_plt
+ && !flag_pic
+ && TARGET_ELF)
+ {
+ /* Avoid PLT. */
+
[PATCH] Extend -fno-plt to normal non-PIC branches on x86
This patch extends -fno-plt to normal non-PIC calls on x86. -fno-plt
works in 64-bit mode with the existing binutils. For 32-bit, we need
the updated assembler and linker to support "call/jmp *foo@GOT" with
a new relocation different from R_386_GOT32 to indicate that this
relocation applies to indirect branches. A configure time check is
added to verify that 32-bit assembler generates a known relocation
which is different from R_386_GOT32. A new 32-bit relocaton is needed
since "call/jmp *foo@GOT" requires a different relocation from R_386_GOT32
which is used together with a GOT register in "call/jmp *foo@GOT(%reg)".
OK for master?
Thanks.
H.J.
---
* configure.ac (HAVE_AS_INDIRECT_BRANCH_VIA_GOT): New. Defined
if 32-bit assembler generates a known relocation which is
different from R_386_GOT32.
* config.in: Regenerated.
* configure: Likewise.
* config/i386/i386.c (ix86_output_call_insn): Extend -fno-plt
to normal non-PIC branches.
---
gcc/config.in | 14 ++
gcc/config/i386/i386.c | 42 --
gcc/configure | 47 ++-
gcc/configure.ac | 18 +-
4 files changed, 113 insertions(+), 8 deletions(-)
diff --git a/gcc/config.in b/gcc/config.in
index daaf906..0ee5c38 100644
--- a/gcc/config.in
+++ b/gcc/config.in
@@ -363,6 +363,12 @@
#endif
+/* Define true if the assembler supports 'call *foo@GOT'. */
+#ifndef USED_FOR_TARGET
+#undef HAVE_AS_INDIRECT_BRANCH_VIA_GOT
+#endif
+
+
/* Define if your assembler supports the Sun syntax for cmov. */
#ifndef USED_FOR_TARGET
#undef HAVE_AS_IX86_CMOV_SUN_SYNTAX
@@ -686,8 +692,8 @@
#endif
-/* Define to 1 if we found a declaration for 'basename', otherwise define to
- 0. */
+/* Define to 1 if you have the declaration of `basename(const char*)', and to
+ 0 if you don't. */
#ifndef USED_FOR_TARGET
#undef HAVE_DECL_BASENAME
#endif
@@ -963,8 +969,8 @@
#endif
-/* Define to 1 if we found a declaration for 'strstr', otherwise define to 0.
- */
+/* Define to 1 if you have the declaration of `strstr(const char*,const
+ char*)', and to 0 if you don't. */
#ifndef USED_FOR_TARGET
#undef HAVE_DECL_STRSTR
#endif
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index e77cd04..5ca19f2 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -25611,7 +25611,26 @@ ix86_output_call_insn (rtx_insn *insn, rtx call_op)
if (SIBLING_CALL_P (insn))
{
if (direct_p)
- xasm = "%!jmp\t%P0";
+ {
+ if (!flag_plt
+ && !flag_pic
+ && !TARGET_MACHO
+ && !TARGET_SEH
+ && !TARGET_PECOFF)
+ {
+ /* Avoid PLT. */
+ if (TARGET_64BIT)
+ xasm = "%!jmp\t*%p0@GOTPCREL(%%rip)";
+ else
+#ifdef HAVE_AS_INDIRECT_BRANCH_VIA_GOT
+ xasm = "%!jmp\t*%p0@GOT";
+#else
+ xasm = "%!jmp\t%P0";
+#endif
+ }
+ else
+ xasm = "%!jmp\t%P0";
+ }
/* SEH epilogue detection requires the indirect branch case
to include REX.W. */
else if (TARGET_SEH)
@@ -25654,7 +25673,26 @@ ix86_output_call_insn (rtx_insn *insn, rtx call_op)
}
if (direct_p)
-xasm = "%!call\t%P0";
+{
+ if (!flag_plt
+ && !flag_pic
+ && !TARGET_MACHO
+ && !TARGET_SEH
+ && !TARGET_PECOFF)
+ {
+ /* Avoid PLT. */
+ if (TARGET_64BIT)
+ xasm = "%!call\t*%p0@GOTPCREL(%%rip)";
+ else
+#ifdef HAVE_AS_INDIRECT_BRANCH_VIA_GOT
+ xasm = "%!call\t*%p0@GOT";
+#else
+ xasm = "%!call\t%P0";
+#endif
+ }
+ else
+ xasm = "%!call\t%P0";
+}
else
xasm = "%!call\t%A0";
diff --git a/gcc/configure b/gcc/configure
index a9a76d6..4419035 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -25361,7 +25361,7 @@ $as_echo "#define HAVE_AS_IX86_DIFF_SECT_DELTA 1"
>>confdefs.h
fi
-# These two are used unconditionally by i386.[ch]; it is to be defined
+# These three are used unconditionally by i386.[ch]; it is to be defined
# to 1 if the feature is present, 0 otherwise.
as_ix86_gotoff_in_data_opt=
if test x$gas = xyes; then
@@ -25407,6 +25407,51 @@ cat >>confdefs.h <<_ACEOF
_ACEOF
+as_ix86_indirect_branch_via_got_opt=
+if test x$gas = xyes; then
+ as_ix86_indirect_branch_via_got_opt="--32"
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for call
*foo@GOT" >&5
+$as_echo_n "checking assembler for call *foo@GOT... " >&6; }
+if test "${gcc_cv_as_ix86_indirect_branch_via_got+set}" = set; then :
+ $as_echo_n "(cached) " >&6
+else
+ gcc_cv_as_ix86_indirect_branch_via_got=no
+if test $in_tree_gas = yes; then
+if test $gcc_cv_gas_vers -ge `expr \( \( 2 \* 1000 \) + 26 \) \* 1000 + 0`
+ then gcc_cv_as_ix86_indirect_branch_via_g
