Add support for position independent executables. This adds compile flags

-fpie & -fPIE which are similar to -fpic & -fPIC except that the resulting
objects can not be used in shared libraries due to an additional
optimization for pie. This also adds the -pie link flag which produces a
pie executable given pic or pie objects.  Combining -pie with -static is
currently disabled. The only gcc3 arch that doesn't support pie at moment
is arm due to binutils relocation bugs.

ok kettenis@

gnu/usr.bin/gcc/gcc/config/arm/openbsd.h

@@ -93,7 +93,7 @@ Boston, MA 02111-1307, USA.  */
 
 #undef SUBTARGET_EXTRA_ASM_SPEC
 #define SUBTARGET_EXTRA_ASM_SPEC	\
-  "-matpcs %{fpic:-k} %{fPIC:-k}"
+  "-matpcs %{fpic|fPIC|fpie|fPIE:-k}"
 
 /* Default floating point model is soft-VFP.
    FIXME: -mhard-float currently implies FPA.  */

gnu/usr.bin/gcc/gcc/config/mips/openbsd.h

@@ -21,7 +21,7 @@ Boston, MA 02111-1307, USA.  */
 /* Definitions needed for OpenBSD, to avoid picking mips 'defaults'.  */
 
 /* GAS must know this.  */
-#define SUBTARGET_ASM_SPEC "%{fPIC:-KPIC} %|"
+#define SUBTARGET_ASM_SPEC "%{fPIC|fPIE:-KPIC} %|"
 
 /* CPP specific OpenBSD specs.  */
 #define SUBTARGET_CPP_SPEC OBSD_CPP_SPEC

gnu/usr.bin/gcc/gcc/config/sparc/openbsd64.h

@@ -52,7 +52,7 @@ Boston, MA 02111-1307, USA.  */
 
 #undef ASM_SPEC
 #define ASM_SPEC "\
-%{v:-V} -s %{fpic:-K PIC} %{fPIC:-K PIC} \
+%{v:-V} -s %{fpic|fPIC|fpie|fPIE:-K PIC} \
 %{mlittle-endian:-EL} \
 %(asm_cpu) %(asm_arch) \
 "

gnu/usr.bin/gcc/gcc/doc/invoke.texi

@@ -304,7 +304,7 @@ in the following sections.
 @item Linker Options
 @xref{Link Options,,Options for Linking}.
 @gccoptlist{@var{object-file-name}  -l@var{library} @gol
--nostartfiles  -nodefaultlibs  -nostdlib @gol
+-nostartfiles  -nodefaultlibs  -nostdlib -pie @gol
 -s  -static  -static-libgcc  -shared  -shared-libgcc  -symbolic @gol
 -Wl,@var{option}  -Xlinker @var{option} @gol
 -u @var{symbol}}
@@ -657,7 +657,7 @@ in the following sections.
 -fasynchronous-unwind-tables @gol
 -finhibit-size-directive  -finstrument-functions @gol
 -fno-common  -fno-ident  -fno-gnu-linker @gol
--fpcc-struct-return  -fpic  -fPIC @gol
+-fpcc-struct-return  -fpic  -fPIC -fpie -fPIE @gol
 -freg-struct-return  -fshared-data  -fshort-enums @gol
 -fshort-double  -fshort-wchar  -fvolatile @gol
 -fvolatile-global  -fvolatile-static @gol
@@ -4620,6 +4620,13 @@ library subroutines.  (For example, @samp{__main}, used to ensure C++
 constructors will be called; @pxref{Collect2,,@code{collect2}, gccint,
 GNU Compiler Collection (GCC) Internals}.)
 
+@item -pie
+@opindex pie
+Produce a position independent executable on targets which support it.
+For predictable results, you must also specify the same set of options
+that were used to generate code (@option{-fpie}, @option{-fPIE},
+or model suboptions) when you specify this option.
+
 @item -s
 @opindex s
 Remove all symbol table and relocation information from the executable.
@@ -10776,6 +10783,15 @@ and the SPARC.
 Position-independent code requires special support, and therefore works
 only on certain machines.
 
+@item -fpie
+@itemx -fPIE
+@opindex fpie
+@opindex fPIE
+These options are similar to @option{-fpic} and @option{-fPIC}, but
+generated position independent code can be only linked into executables.
+Usually these options are used when @option{-pie} GCC option will be
+used during linking.
+
 @item -ffixed-@var{reg}
 @opindex ffixed
 Treat the register named @var{reg} as a fixed register; generated code

gnu/usr.bin/gcc/gcc/flags.h

@@ -483,6 +483,16 @@ extern int flag_pedantic_errors;
 
 extern int flag_pic;
 
+/* Nonzero if we are compiling position independent code for executable.
+   1 vs 2 for a target-dependent "small" or "large" mode.  */
+
+extern int flag_pie;
+
+/* Nonzero if we are compiling code for a shared library, zero for
+   executable.  */
+
+extern int flag_shlib;
+
 /* Nonzero means generate extra code for exception handling and enable
    exception handling.  */
 

gnu/usr.bin/gcc/gcc/gcc.c

@@ -639,6 +639,8 @@ proper position among the other output files.  */
 #define LINK_GCC_C_SEQUENCE_SPEC "%G %L %G"
 #endif
 
+#define LINK_PIE_SPEC "%{pie: -pie}"
+
 /* -u* was put back because both BSD and SysV seem to support it.  */
 /* %{static:} simply prevents an error message if the target machine
    doesn't handle -static.  */
@@ -647,8 +649,12 @@ proper position among the other output files.  */
    directories.  */
 #ifndef LINK_COMMAND_SPEC
 #define LINK_COMMAND_SPEC "\
+%{pie:%{static:%e-pie and -static options are incompatible}} \
+%{shared:%{pie:%e-shared and -pie options are incompatible}} \
+%{pie:%{pg|p:%e-pie and -pg|p options are incompatible}} \
 %{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:\
     %(linker) %l %X %{o*} %{A} %{d} %{e*} %{m} %{N} %{n} %{r} %{s} %{t}\
+    " LINK_PIE_SPEC "\
     %{u*} %{x} %{z} %{Z} %{!A:%{!nostdlib:%{!nostartfiles:%S}}}\
     %{static:} %{L*} %(link_libgcc) %o %{!nostdlib:%{!nodefaultlibs:%(link_gcc_c_sequence)}}\
     %{!A:%{!nostdlib:%{!nostartfiles:%E}}} %{T*} }}}}}}"
@@ -973,6 +979,7 @@ static const struct option_map option_map[] =
    {"--output-class-directory", "-foutput-class-dir=", "ja"},
    {"--param", "--param", "a"},
    {"--pedantic", "-pedantic", 0},
+   {"--pie", "-pie", 0},
    {"--pedantic-errors", "-pedantic-errors", 0},
    {"--pipe", "-pipe", 0},
    {"--prefix", "-B", "a"},

gnu/usr.bin/gcc/gcc/toplev.c

@@ -710,6 +710,17 @@ int flag_delayed_branch;
 
 int flag_pic;
 
+/* Nonzero if we are compiling position independent code for executable.
+   The value is 1 if we are doing "small" pic; value is 2 if we're doing
+   "large" pic.  */
+int flag_pie;
+
+/* Nonzero if we are compiling code for a shared library, zero for
+   executable.  */
+
+int flag_shlib;
+
+
 /* Set to the default thread-local storage (tls) model to use.  */
 
 enum tls_model flag_tls_default = TLS_MODEL_GLOBAL_DYNAMIC;
@@ -1102,6 +1113,9 @@ static const lang_independent_options f_options[] =
   {"pic", &flag_pic, 1,
    N_("Generate position independent code, if possible") },
   {"PIC", &flag_pic, 2, ""},
+  {"pie", &flag_pie, 1,
+   N_("Generate position independent code for executables, if possible") },
+  {"PIE", &flag_pie, 2, ""},
   {"exceptions", &flag_exceptions, 1,
    N_("Enable exception handling") },
   {"unwind-tables", &flag_unwind_tables, 1,
@@ -5083,6 +5097,12 @@ parse_options_and_default_flags (argc, argv)
 	}
     }
 
+  if (flag_pie)
+    flag_pic = flag_pie;
+
+  if (flag_pic && !flag_pie)
+    flag_shlib = 1;
+
   if (flag_no_inline == 2)
     flag_no_inline = 0;
   else

gnu/usr.bin/gcc/gcc/varasm.c

@@ -5460,7 +5460,7 @@ bool
 default_binds_local_p (exp)
      tree exp;
 {
-  return default_binds_local_p_1 (exp, flag_pic);
+  return default_binds_local_p_1 (exp, flag_shlib);
 }
 
 bool