i386.opt: New target option -mx87regparm.

	* config/i386/i386.opt: New target option -mx87regparm.

	* config/i386/i386.h (struct ix86_args): Add x87_nregs, x87_regno,
	float_in_x87: Add new variables. mmx_words, sse_words: Remove.
	(X87_REGPARM_MAX): Define.

	* config/i386/i386.c (override_options): Error out for
	-mx87regparm but no 80387 support.
	(ix86_attribute_table): Add x87regparm.
	(ix86_handle_cconv_attribute): Update comments for x87regparm.
	(ix86_comp_type_attributes): Check for mismatched x87regparm types.
	(ix86_function_x87regparm): New function.
	(ix86_function_arg_regno_p): Add X87_REGPARM_MAX 80387 floating
	point registers.
	(init_cumulative_args): Initialize x87_nregs and float_in_x87
	variables.
	(function_arg_advance): Process x87_nregs and x87_regno when
	floating point argument is to be passed in 80387 register.
	(function_arg): Pass XFmode arguments in 80387 registers for local
	functions.  Pass SFmode and DFmode arguments to local functions
	in 80387 registers when flag_unsafe_math_optimizations is set.

	* reg-stack.c (convert_regs_entry): Disable NaN load for
	stack registers that are used for argument passing.

	* doc/extend.texi: Document x87regparm function attribute.
	* doc/invoke.texi: Document -mx87regparm.

testsuite/ChangeLog:

	* gcc.target/i386/x87regparm-1.c: New test.
	* gcc.target/i386/x87regparm-2.c: New test.
	* gcc.target/i386/x87regparm-3.c: New test.
	* gcc.target/i386/x87regparm-4.c: New test.

From-SVN: r118859

2 files changed, 21 insertions, 2 deletions

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 2a1391e..099e4dd 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -2221,6 +2221,14 @@ safe since the loaders there save all registers.  (Lazy binding can be
 disabled with the linker or the loader if desired, to avoid the
 problem.)
 
+@item x87regparm
+@cindex @code{x87regparm} attribute
+On the Intel x86 with 80387 @code{x87regparm} attribute causes the
+compiler to pass up to 3 floating point arguments in 80387 registers
+instead of on the stack.  Functions that take a variable number of
+arguments will continue to pass all of their floating point arguments
+on the stack.
+
 @item sseregparm
 @cindex @code{sseregparm} attribute
 On the Intel 386 with SSE support, the @code{sseregparm} attribute
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 544467e..1a62289 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -535,8 +535,8 @@ Objective-C and Objective-C++ Dialects}.
 -mmmx  -msse  -msse2 -msse3 -mssse3 -m3dnow @gol
 -mthreads  -mno-align-stringops  -minline-all-stringops @gol
 -mpush-args  -maccumulate-outgoing-args  -m128bit-long-double @gol
--m96bit-long-double  -mregparm=@var{num}  -msseregparm @gol
--mstackrealign @gol
+-m96bit-long-double  -mregparm=@var{num}  -mx87regparm @gol
+-msseregparm @gol  -mstackrealign @gol
 -momit-leaf-frame-pointer  -mno-red-zone -mno-tls-direct-seg-refs @gol
 -mcmodel=@var{code-model} @gol
 -m32  -m64 -mlarge-data-threshold=@var{num}}
@@ -9542,6 +9542,17 @@ function by using the function attribute @samp{regparm}.
 value, including any libraries.  This includes the system libraries and
 startup modules.
 
+@item -mx87regparm
+@opindex mx87regparm
+Use 80387 register passing conventions for floating point arguments.
+You can control this behavior for a specific function by using the
+function attribute @samp{x87regparm}.
+@xref{Function Attributes}.
+
+@strong{Warning:} if you use this switch then you must build all
+modules with the same value, including any libraries.  This includes
+the system libraries and startup modules.
+
 @item -msseregparm
 @opindex msseregparm
 Use SSE register passing conventions for float and double arguments