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[committed] Add support for dynamic non-PIC MIPS executables
- From: Richard Sandiford <rdsandiford at googlemail dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Sun, 17 Aug 2008 11:51:10 +0100
- Subject: [committed] Add support for dynamic non-PIC MIPS executables
This patch adds support for dynamic non-PIC MIPS executables.
Thanks to Dan for all the merging work.
Tested on mips64-linux-gnu and applied.
I've also attached a draft changes.html patch. Comments welcome!
Richard
gcc/
2008-08-17 Daniel Jacobowitz <dan@codesourcery.com>
Richard Sandiford <rdsandiford@googlemail.com>
* doc/install.texi (--with-mips-plt): Document.
* doc/invoke.texi (-mplt, -mno-plt): Document.
* config.gcc (mips*-*-*): Add mips-plt to supported_defaults
and handle ${with_mips_plt}.
* config/mips/mips.opt (mplt): New option.
* config/mips/mips.h (TARGET_ABICALLS_PIC0): New macro.
(TARGET_ABICALLS_PIC2): Likewise.
(TARGET_GPWORD): Return false for TARGET_ABSOLUTE_ABICALLS.
(OPTION_DEFAULT_SPECS): Add a mips-plt entry.
(ASM_SPEC): Use !mabi=* instead of !mabi*.
(MIPS_CALL): Use TARGET_ABICALLS_PIC2 instead of TARGET_ABICALLS
to decide whether to output ".option picX" directives.
* config/mips/linux.h (SUBTARGET_ASM_SPEC): Remove -mabi=64 handling.
Pass -call_nonpic rather than -KPIC for -mplt.
(BASE_DRIVER_SELF_SPECS): Remove -mplt if -mno-shared is not present
on the command line. Also remove it when -mabi=64 is used without
-msym32.
* config/mips/linux64.h (SUBTARGET_ASM_SPEC): Delete.
* config/mips/mips.c (mips_use_pic_fn_addr_reg_p): Handle
TARGET_ABICALLS_PIC0.
(mips_classify_symbol): Use TARGET_ABICALLS_PIC2 instead of
TARGET_ABICALLS.
(mips16_build_function_stub): Only output ".option pic" directives
and PIC stubs if TARGET_ABICALLS_PIC2. Call through $25 instead of $1.
(mips16_build_call_stub): Fix comment and remove redundant
".set at"/"set .noat" directives.
(mips_function_rodata_section): Use the default behaviour for
TARGET_ABSOLUTE_ABICALLS.
(mips_file_start): Emit ".option pic0" for TARGET_ABICALLS_PIC0.
(mips_global_pointer): Handle TARGET_ABICALLS_PIC0.
(mips_restore_gp): Do nothing if the current function doesn't use
a global pointer.
(mips_expand_prologue): Only save $gp if the current function uses it.
Use a normal move for TARGET_ABICALLS_PIC0.
(mips_override_options): Only set flag_pic if TARGET_ABICALLS_PIC2.
Index: gcc/doc/install.texi
===================================================================
--- gcc/doc/install.texi 2008-08-17 08:53:58.000000000 +0100
+++ gcc/doc/install.texi 2008-08-17 08:54:03.000000000 +0100
@@ -1076,6 +1076,12 @@ not provide them.
On MIPS targets, make @option{-mno-llsc} the default when no
@option{-mllsc} option is passed.
+@item --with-mips-plt
+On MIPS targets, make use of copy relocations and PLTs.
+These features are extensions to the traditional
+SVR4-based MIPS ABIs and require support from GNU binutils
+and the runtime C library.
+
@item --enable-__cxa_atexit
Define if you want to use __cxa_atexit, rather than atexit, to
register C++ destructors for local statics and global objects.
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi 2008-08-17 08:53:57.000000000 +0100
+++ gcc/doc/invoke.texi 2008-08-17 08:54:03.000000000 +0100
@@ -634,8 +634,8 @@ Objective-C and Objective-C++ Dialects}.
-mips16 -mno-mips16 -mflip-mips16 @gol
-minterlink-mips16 -mno-interlink-mips16 @gol
-mabi=@var{abi} -mabicalls -mno-abicalls @gol
--mshared -mno-shared -mxgot -mno-xgot -mgp32 -mgp64 @gol
--mfp32 -mfp64 -mhard-float -msoft-float @gol
+-mshared -mno-shared -mplt -mno-plt -mxgot -mno-xgot @gol
+-mgp32 -mgp64 -mfp32 -mfp64 -mhard-float -msoft-float @gol
-msingle-float -mdouble-float -mdsp -mno-dsp -mdspr2 -mno-dspr2 @gol
-msmartmips -mno-smartmips @gol
-mpaired-single -mno-paired-single -mdmx -mno-mdmx @gol
@@ -12160,6 +12160,19 @@ executables both smaller and quicker.
@option{-mshared} is the default.
+@item -mplt
+@itemx -mno-plt
+@opindex mplt
+@opindex mno-plt
+Assume (do not assume) that the static and dynamic linkers
+support PLTs and copy relocations. This option only affects
+@samp{-mno-shared -mabicalls}. For the n64 ABI, this option
+has no effect without @samp{-msym32}.
+
+You can make @option{-mplt} the default by configuring
+GCC with @option{--with-mips-plt}. The default is
+@option{-mno-plt} otherwise.
+
@item -mxgot
@itemx -mno-xgot
@opindex mxgot
Index: gcc/config.gcc
===================================================================
--- gcc/config.gcc 2008-08-17 08:53:58.000000000 +0100
+++ gcc/config.gcc 2008-08-17 08:54:03.000000000 +0100
@@ -2779,7 +2779,7 @@ case "${target}" in
;;
mips*-*-*)
- supported_defaults="abi arch float tune divide llsc"
+ supported_defaults="abi arch float tune divide llsc mips-plt"
case ${with_float} in
"" | soft | hard)
@@ -2826,6 +2826,21 @@ case "${target}" in
exit 1
;;
esac
+
+ case ${with_mips_plt} in
+ yes)
+ with_mips_plt=plt
+ ;;
+ no)
+ with_mips_plt=no-plt
+ ;;
+ "")
+ ;;
+ *)
+ echo "Unknown --with-mips-plt argument: $with_mips_plt" 1>&2
+ exit 1
+ ;;
+ esac
;;
powerpc*-*-* | rs6000-*-*)
@@ -3078,10 +3093,10 @@ case ${target} in
esac
t=
-all_defaults="abi cpu cpu_32 cpu_64 arch arch_32 arch_64 tune tune_32 tune_64 schedule float mode fpu divide llsc"
+all_defaults="abi cpu cpu_32 cpu_64 arch arch_32 arch_64 tune tune_32 tune_64 schedule float mode fpu divide llsc mips-plt"
for option in $all_defaults
do
- eval "val=\$with_$option"
+ eval "val=\$with_"`echo $option | sed s/-/_/g`
if test -n "$val"; then
case " $supported_defaults " in
*" $option "*)
Index: gcc/config/mips/mips.opt
===================================================================
--- gcc/config/mips/mips.opt 2008-08-17 08:53:58.000000000 +0100
+++ gcc/config/mips/mips.opt 2008-08-17 08:54:03.000000000 +0100
@@ -160,6 +160,10 @@ mgpopt
Target Report Var(TARGET_GPOPT) Init(1)
Use GP-relative addressing to access small data
+mplt
+Target Report Var(TARGET_PLT)
+When generating -mabicalls code, allow executables to use PLTs and copy relocations
+
mhard-float
Target Report RejectNegative InverseMask(SOFT_FLOAT_ABI, HARD_FLOAT_ABI)
Allow the use of hardware floating-point ABI and instructions
Index: gcc/config/mips/mips.h
===================================================================
--- gcc/config/mips/mips.h 2008-08-17 08:53:58.000000000 +0100
+++ gcc/config/mips/mips.h 2008-08-17 08:54:03.000000000 +0100
@@ -148,6 +148,15 @@ #define BITMASK_LOWER16 ((unsigned long)
/* True if we are generating position-independent VxWorks RTP code. */
#define TARGET_RTP_PIC (TARGET_VXWORKS_RTP && flag_pic)
+/* True if the output file is marked as ".abicalls; .option pic0"
+ (-call_nonpic). */
+#define TARGET_ABICALLS_PIC0 \
+ (TARGET_ABSOLUTE_ABICALLS && TARGET_PLT)
+
+/* True if the output file is marked as ".abicalls; .option pic2" (-KPIC). */
+#define TARGET_ABICALLS_PIC2 \
+ (TARGET_ABICALLS && !TARGET_ABICALLS_PIC0)
+
/* True if the call patterns should be split into a jalr followed by
an instruction to restore $gp. It is only safe to split the load
from the call when every use of $gp is explicit. */
@@ -200,7 +209,10 @@ #define TARGET_USE_PIC_FN_ADDR_REG (TARG
Although GAS does understand .gpdword, the SGI linker mishandles
the relocations GAS generates (R_MIPS_GPREL32 followed by R_MIPS_64).
We therefore disable GP-relative switch tables for n64 on IRIX targets. */
-#define TARGET_GPWORD (TARGET_ABICALLS && !(mips_abi == ABI_64 && TARGET_IRIX))
+#define TARGET_GPWORD \
+ (TARGET_ABICALLS \
+ && !TARGET_ABSOLUTE_ABICALLS \
+ && !(mips_abi == ABI_64 && TARGET_IRIX))
/* Generate mips16 code */
#define TARGET_MIPS16 ((target_flags & MASK_MIPS16) != 0)
@@ -715,7 +727,8 @@ #define OPTION_DEFAULT_SPECS \
{"abi", "%{!mabi=*:-mabi=%(VALUE)}" }, \
{"float", "%{!msoft-float:%{!mhard-float:-m%(VALUE)-float}}" }, \
{"divide", "%{!mdivide-traps:%{!mdivide-breaks:-mdivide-%(VALUE)}}" }, \
- {"llsc", "%{!mllsc:%{!mno-llsc:-m%(VALUE)}}" }
+ {"llsc", "%{!mllsc:%{!mno-llsc:-m%(VALUE)}}" }, \
+ {"mips-plt", "%{!mplt:%{!mno-plt:-m%(VALUE)}}" }
#define GENERATE_DIVIDE_TRAPS (TARGET_DIVIDE_TRAPS \
@@ -1074,7 +1087,7 @@ #define ASM_SPEC "\
%{mfix-vr4120} %{mfix-vr4130} \
%(subtarget_asm_optimizing_spec) \
%(subtarget_asm_debugging_spec) \
-%{mabi=*} %{!mabi*: %(asm_abi_default_spec)} \
+%{mabi=*} %{!mabi=*: %(asm_abi_default_spec)} \
%{mgp32} %{mgp64} %{march=*} %{mxgot:-xgot} \
%{mfp32} %{mfp64} \
%{mshared} %{mno-shared} \
@@ -2559,7 +2572,7 @@ #define MIPS_CALL(INSN, OPERANDS, OPNO)
? "%*" INSN "\t%" #OPNO "%/" \
: REG_P (OPERANDS[OPNO]) \
? "%*" INSN "r\t%" #OPNO "%/" \
- : TARGET_ABICALLS \
+ : TARGET_ABICALLS_PIC2 \
? (".option\tpic0\n\t" \
"%*" INSN "\t%" #OPNO "%/\n\t" \
".option\tpic2") \
Index: gcc/config/mips/linux.h
===================================================================
--- gcc/config/mips/linux.h 2008-08-17 08:53:58.000000000 +0100
+++ gcc/config/mips/linux.h 2008-08-17 08:54:03.000000000 +0100
@@ -79,7 +79,8 @@ #define LINK_SPEC \
%{static:-static}}}"
#undef SUBTARGET_ASM_SPEC
-#define SUBTARGET_ASM_SPEC "%{mabi=64: -64} %{!mno-abicalls:-KPIC}"
+#define SUBTARGET_ASM_SPEC \
+ "%{!mno-abicalls:%{mplt:-call_nonpic;:-KPIC}}"
/* The MIPS assembler has different syntax for .set. We set it to
.dummy to trap any errors. */
@@ -134,6 +135,11 @@ extern const char *host_detect_local_cpu
#endif
#define BASE_DRIVER_SELF_SPECS \
- NO_SHARED_SPECS \
- MARCH_MTUNE_NATIVE_SPECS
+ NO_SHARED_SPECS \
+ MARCH_MTUNE_NATIVE_SPECS, \
+ /* -mplt has no effect without -mno-shared. Simplify later \
+ specs handling by removing a redundant option. */ \
+ "%{!mno-shared:%<mplt}", \
+ /* -mplt likewise has no effect for -mabi=64 without -msym32. */ \
+ "%{mabi=64:%{!msym32:%<mplt}}"
#define DRIVER_SELF_SPECS BASE_DRIVER_SELF_SPECS
Index: gcc/config/mips/linux64.h
===================================================================
--- gcc/config/mips/linux64.h 2008-08-17 08:53:58.000000000 +0100
+++ gcc/config/mips/linux64.h 2008-08-17 08:54:03.000000000 +0100
@@ -26,11 +26,6 @@ #define DRIVER_SELF_SPECS \
" %{!EB:%{!EL:%(endian_spec)}}" \
" %{!mabi=*: -mabi=n32}"
-#undef SUBTARGET_ASM_SPEC
-#define SUBTARGET_ASM_SPEC "\
-%{!fno-PIC:%{!fno-pic:-KPIC}} \
-%{fno-PIC:-non_shared} %{fno-pic:-non_shared}"
-
#undef LIB_SPEC
#define LIB_SPEC "\
%{pthread:-lpthread} \
Index: gcc/config/mips/mips.c
===================================================================
--- gcc/config/mips/mips.c 2008-08-17 08:54:01.000000000 +0100
+++ gcc/config/mips/mips.c 2008-08-17 08:54:03.000000000 +0100
@@ -1454,13 +1454,20 @@ mips_use_pic_fn_addr_reg_p (const_rtx x)
if (mips16_stub_function_p (x))
return false;
- /* When TARGET_ABSOLUTE_ABICALLS is true, locally-defined functions
- use absolute accesses to set up the global pointer. */
- if (TARGET_ABSOLUTE_ABICALLS
- && GET_CODE (x) == SYMBOL_REF
- && mips_symbol_binds_local_p (x)
- && !SYMBOL_REF_EXTERNAL_P (x))
- return false;
+ if (GET_CODE (x) == SYMBOL_REF)
+ {
+ /* If PLTs and copy relocations are available, the static linker
+ will make sure that $25 is valid on entry to the target function. */
+ if (TARGET_ABICALLS_PIC0)
+ return false;
+
+ /* Locally-defined functions use absolute accesses to set up
+ the global pointer. */
+ if (TARGET_ABSOLUTE_ABICALLS
+ && mips_symbol_binds_local_p (x)
+ && !SYMBOL_REF_EXTERNAL_P (x))
+ return false;
+ }
return true;
}
@@ -1512,7 +1519,7 @@ mips_classify_symbol (const_rtx x, enum
/* Don't use GOT accesses for locally-binding symbols when -mno-shared
is in effect. */
- if (TARGET_ABICALLS
+ if (TARGET_ABICALLS_PIC2
&& !(TARGET_ABSOLUTE_ABICALLS && mips_symbol_binds_local_p (x)))
{
/* There are three cases to consider:
@@ -5657,35 +5664,36 @@ mips16_build_function_stub (void)
assemble_start_function (stubdecl, stubname);
mips_start_function_definition (stubname, false);
- /* If generating abicalls code, either set up the global pointer or
- switch to absolute mode. */
- if (TARGET_ABSOLUTE_ABICALLS)
- fprintf (asm_out_file, "\t.option\tpic0\n");
- else if (TARGET_ABICALLS)
+ /* If generating pic2 code, either set up the global pointer or
+ switch to pic0. */
+ if (TARGET_ABICALLS_PIC2)
{
- output_asm_insn ("%(.cpload\t%^%)", NULL);
- /* Emit an R_MIPS_NONE relocation to tell the linker what the
- target function is. Use a local GOT access when loading the
- symbol, to cut down on the number of unnecessary GOT entries
- for stubs that aren't needed. */
- output_asm_insn (".reloc\t0,R_MIPS_NONE,%0", &symbol);
- symbol = alias;
+ if (TARGET_ABSOLUTE_ABICALLS)
+ fprintf (asm_out_file, "\t.option\tpic0\n");
+ else
+ {
+ output_asm_insn ("%(.cpload\t%^%)", NULL);
+ /* Emit an R_MIPS_NONE relocation to tell the linker what the
+ target function is. Use a local GOT access when loading the
+ symbol, to cut down on the number of unnecessary GOT entries
+ for stubs that aren't needed. */
+ output_asm_insn (".reloc\t0,R_MIPS_NONE,%0", &symbol);
+ symbol = alias;
+ }
}
- /* Load the address of the MIPS16 function into $at. Do this first so
+ /* Load the address of the MIPS16 function into $25. Do this first so
that targets with coprocessor interlocks can use an MFC1 to fill the
delay slot. */
- fprintf (asm_out_file, "\t.set\tnoat\n");
- output_asm_insn ("la\t%@,%0", &symbol);
+ output_asm_insn ("la\t%^,%0", &symbol);
/* Move the arguments from floating-point registers to general registers. */
mips_output_args_xfer (crtl->args.info.fp_code, 'f');
/* Jump to the MIPS16 function. */
- output_asm_insn ("jr\t%@", NULL);
- fprintf (asm_out_file, "\t.set\tat\n");
+ output_asm_insn ("jr\t%^", NULL);
- if (TARGET_ABSOLUTE_ABICALLS)
+ if (TARGET_ABICALLS_PIC2 && TARGET_ABSOLUTE_ABICALLS)
fprintf (asm_out_file, "\t.option\tpic2\n");
mips_end_function_definition (stubname);
@@ -5906,10 +5914,9 @@ mips16_build_call_stub (rtx retval, rtx
if (!fp_ret_p)
{
- /* Load the address of the MIPS16 function into $at. Do this
+ /* Load the address of the MIPS16 function into $25. Do this
first so that targets with coprocessor interlocks can use
an MFC1 to fill the delay slot. */
- fprintf (asm_out_file, "\t.set\tnoat\n");
if (TARGET_EXPLICIT_RELOCS)
{
output_asm_insn ("lui\t%^,%%hi(%0)", &fn);
@@ -5927,7 +5934,6 @@ mips16_build_call_stub (rtx retval, rtx
{
/* Jump to the previously-loaded address. */
output_asm_insn ("jr\t%^", NULL);
- fprintf (asm_out_file, "\t.set\tat\n");
}
else
{
@@ -7222,15 +7228,16 @@ mips_select_rtx_section (enum machine_mo
/* Implement TARGET_ASM_FUNCTION_RODATA_SECTION.
The complication here is that, with the combination TARGET_ABICALLS
- && !TARGET_GPWORD, jump tables will use absolute addresses, and should
- therefore not be included in the read-only part of a DSO. Handle such
- cases by selecting a normal data section instead of a read-only one.
- The logic apes that in default_function_rodata_section. */
+ && !TARGET_ABSOLUTE_ABICALLS && !TARGET_GPWORD, jump tables will use
+ absolute addresses, and should therefore not be included in the
+ read-only part of a DSO. Handle such cases by selecting a normal
+ data section instead of a read-only one. The logic apes that in
+ default_function_rodata_section. */
static section *
mips_function_rodata_section (tree decl)
{
- if (!TARGET_ABICALLS || TARGET_GPWORD)
+ if (!TARGET_ABICALLS || TARGET_ABSOLUTE_ABICALLS || TARGET_GPWORD)
return default_function_rodata_section (decl);
if (decl && DECL_SECTION_NAME (decl))
@@ -7729,7 +7736,11 @@ mips_file_start (void)
/* If TARGET_ABICALLS, tell GAS to generate -KPIC code. */
if (TARGET_ABICALLS)
- fprintf (asm_out_file, "\t.abicalls\n");
+ {
+ fprintf (asm_out_file, "\t.abicalls\n");
+ if (TARGET_ABICALLS_PIC0)
+ fprintf (asm_out_file, "\t.option\tpic0\n");
+ }
if (flag_verbose_asm)
fprintf (asm_out_file, "\n%s -G value = %d, Arch = %s, ISA = %d\n",
@@ -8285,24 +8296,40 @@ mips_global_pointer (void)
if (crtl->has_nonlocal_goto)
return GLOBAL_POINTER_REGNUM;
- /* If the gp is never referenced, there's no need to initialize it.
- Note that reload can sometimes introduce constant pool references
- into a function that otherwise didn't need them. For example,
- suppose we have an instruction like:
-
- (set (reg:DF R1) (float:DF (reg:SI R2)))
-
- If R2 turns out to be constant such as 1, the instruction may have a
- REG_EQUAL note saying that R1 == 1.0. Reload then has the option of
- using this constant if R2 doesn't get allocated to a register.
-
- In cases like these, reload will have added the constant to the pool
- but no instruction will yet refer to it. */
+ /* There's no need to initialize $gp if it isn't referenced now,
+ and if we can be sure that no new references will be added during
+ or after reload. */
if (!df_regs_ever_live_p (GLOBAL_POINTER_REGNUM)
- && !crtl->uses_const_pool
- && !mips16_cfun_returns_in_fpr_p ()
&& !mips_function_has_gp_insn ())
- return 0;
+ {
+ /* The function doesn't use $gp at the moment. If we're generating
+ -call_nonpic code, no new uses will be introduced during or after
+ reload. */
+ if (TARGET_ABICALLS_PIC0)
+ return 0;
+
+ /* We need to handle the following implicit gp references:
+
+ - Reload can sometimes introduce constant pool references
+ into a function that otherwise didn't need them. For example,
+ suppose we have an instruction like:
+
+ (set (reg:DF R1) (float:DF (reg:SI R2)))
+
+ If R2 turns out to be constant such as 1, the instruction may
+ have a REG_EQUAL note saying that R1 == 1.0. Reload then has
+ the option of using this constant if R2 doesn't get allocated
+ to a register.
+
+ In cases like these, reload will have added the constant to the
+ pool but no instruction will yet refer to it.
+
+ - MIPS16 functions that return in FPRs need to call an
+ external libgcc routine. */
+ if (!crtl->uses_const_pool
+ && !mips16_cfun_returns_in_fpr_p ())
+ return 0;
+ }
/* We need a global pointer, but perhaps we can use a call-clobbered
register instead of $gp. */
@@ -8694,6 +8721,9 @@ mips_restore_gp (rtx temp)
{
gcc_assert (TARGET_ABICALLS && TARGET_OLDABI);
+ if (cfun->machine->global_pointer == 0)
+ return;
+
if (TARGET_MIPS16)
{
mips_emit_move (temp, mips_cprestore_slot (temp));
@@ -9121,13 +9151,17 @@ mips_expand_prologue (void)
mips_emit_loadgp ();
/* Initialize the $gp save slot. */
- if (frame->cprestore_size > 0)
+ if (frame->cprestore_size > 0
+ && cfun->machine->global_pointer != 0)
{
if (TARGET_MIPS16)
mips_emit_move (mips_cprestore_slot (MIPS_PROLOGUE_TEMP (Pmode)),
MIPS16_PIC_TEMP);
- else
+ else if (TARGET_ABICALLS_PIC2)
emit_insn (gen_cprestore (GEN_INT (frame->args_size)));
+ else
+ emit_move_insn (mips_cprestore_slot (MIPS_PROLOGUE_TEMP (Pmode)),
+ pic_offset_table_rtx);
}
/* If we are profiling, make sure no instructions are scheduled before
@@ -13196,14 +13230,16 @@ mips_override_options (void)
target_flags &= ~MASK_ABICALLS;
}
- if (TARGET_ABICALLS)
+ if (TARGET_ABICALLS_PIC2)
/* We need to set flag_pic for executables as well as DSOs
because we may reference symbols that are not defined in
the final executable. (MIPS does not use things like
copy relocs, for example.)
- Also, there is a body of code that uses __PIC__ to distinguish
- between -mabicalls and -mno-abicalls code. */
+ There is a body of code that uses __PIC__ to distinguish
+ between -mabicalls and -mno-abicalls code. The non-__PIC__
+ variant is usually appropriate for TARGET_ABICALLS_PIC0, as
+ long as any indirect jumps use $25. */
flag_pic = 1;
/* -mvr4130-align is a "speed over size" optimization: it usually produces
Index: htdocs/gcc-4.4/changes.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-4.4/changes.html,v
retrieving revision 1.20
diff -u -p -r1.20 changes.html
--- htdocs/gcc-4.4/changes.html 25 Jul 2008 08:39:11 -0000 1.20
+++ htdocs/gcc-4.4/changes.html 17 Aug 2008 10:49:25 -0000
@@ -172,6 +172,23 @@
<h3>MIPS</h3>
<ul>
+ <li><p>MIPS Technologies have extended the original MIPS SVR4 ABI
+ to include support for procedure linkage tables (PLTs)
+ and copy relocations. These extensions allow GNU/Linux
+ executables to use a significantly more efficient code
+ model than the one defined by the original ABI.</p>
+
+ <p>GCC support for this code model is available via a
+ new command-line option, <code>-mplt</code>. There is also
+ a new configure-time option, <code>--with-mips-plt</code>,
+ to make <code>-mplt</code> the default.</p>
+
+ <p>The new code model requires support from the assembler,
+ the linker, and the runtime C library. This support is available
+ in binutils 2.19 and GLIBC 2.9.</p></li>
+ <li>GCC can now generate MIPS16 code for 32-bit GNU/Linux executables
+ and 32-bit GNU/Linux shared libraries. This feature requires
+ GNU binutils 2.19 or above.</li>
<li>Support for RMI's XLR processor is now available through the
<code>-march=xlr</code> and <code>-mtune=xlr</code> options.</li>
<li>64-bit targets can now perform 128-bit multiplications inline,