invoke.texi (generic): Document (i686) Update.

	* invoke.texi (generic): Document
	(i686) Update.
	* config.gcc: Make x86_64-* and i686-* default to generic tunning.
	* i386.h (TARGET_GENERIC32, TARGET_GENERIC64, TARGET_GENERIC,
	TARGET_USE_INCDEC, TARGET_PAD_RETURNS): New macros.
	(x86_use_incdec, x86_pad_returns): New variables
	(TARGET_CPU_DEFAULT_generic): New constant
	(TARGET_CPU_DEFAULT_NAMES): Add generic.
	(enum processor_type): Add generic32 and generic64.
	* i386.md (cpu attribute): Add generic32/generic64
	(movhi splitter): Behave sanely when both partial_reg_dependency and
	partial_reg_stall are set.
	(K8 splitters): Enable for generic as well.
	* predicates.md (incdec_operand): Use TARGET_INCDEC
	(aligned_operand): Avoid memory mismatch stalls.
	* athlon.md: Enable for generic64, new patterns for 128bit moves.
	* ppro.md: Enable for generic32
	* i386.c (generic64_cost, generic32_cost): New.
	(m_GENERIC32, m_GENERIC64, m_GENERIC): New macros.
	(x86_use_leave): Enable for generic64.  (x86_use_sahf,
	x86_ext_80387_constants): Enable for generic32.  (x86_push_memory,
	x86_movx, x86_unroll_strlen, x86_deep_branch, x86_use_simode_fiop,
	x86_use_cltd, x86_promote_QImode, x86_sub_esp_4, x86_sub_esp_8,
	x86_add_esp_4, x86_add_esp_8, x86_integer_DFmode_moves,
	x86_partial_reg_dependency, x86_memory_mismatch_stall,
	x86_accumulate_outgoing_args, x86_prologue_using_move,
	x86_epilogue_using_move, x86_arch_always_fancy_math_387,
	x86_sse_partial_reg_dependency, x86_four_jump_limit, x86_schedule):
	Enable for generic.
	(x86_use_incdec, x86_pad_returns): New.
	(override_options): Add generic32 and generic64, translate "generic"
	to generic32/generic64 and "i686" to "generic32", refuse
	"generic32"/"generic64" as arch target.
	(ix86_issue_rate, ix86_adjust_cost): Handle generic as athlon.
	(ix86_reorg): Honor PAD_RETURNS.

From-SVN: r109972

gcc/doc/invoke.texi

@@ -9062,6 +9062,23 @@ Tune to @var{cpu-type} everything applicable about the generated code, except
 for the ABI and the set of available instructions.  The choices for
 @var{cpu-type} are:
 @table @emph
+@item generic
+Produce code optimized for the most common IA32/AMD64/EM64T processors.
+If you know the CPU on which your code will run, then you should use
+the corresponding @option{-mtune} option instead of
+@option{-mtune=generic}.  But, if you do not know exactly what CPU users
+of your application will have, then you should use this option.
+
+As new processors are deployed in the marketplace, the behavior of this
+option will change.  Therefore, if you upgrade to a newer version of
+GCC, the code generated option will change to reflect the processors
+that were most common when that version of GCC was released.
+
+There is no @option{-march=generic} option because @option{-march}
+indicates the instruction set the compiler can use, and there is no
+generic instruction set applicable to all processors.  In contrast,
+@option{-mtune} indicates the processor (or, in this case, collection of
+processors) for which the code is optimized.
 @item i386
 Original Intel's i386 CPU@.
 @item i486
@@ -9070,8 +9087,11 @@ Intel's i486 CPU@.  (No scheduling is implemented for this chip.)
 Intel Pentium CPU with no MMX support.
 @item pentium-mmx
 Intel PentiumMMX CPU based on Pentium core with MMX instruction set support.
-@item i686, pentiumpro
+@item pentiumpro
 Intel PentiumPro CPU@.
+@item i686
+Same as @code{generic}, but when used as @code{march} option, PentiumPro
+instruction set will be used, so the code will run on all i686 familly chips.
 @item pentium2
 Intel Pentium2 CPU based on PentiumPro core with MMX instruction set support.
 @item pentium3, pentium3m