[patch mips/gcc] add build-time and runtime options to disable or set madd.fmt type

[Yunqiang Su <Yunqiang dot Su at imgtec dot com>]

By this patch, I add 
    build-time options:
         —with-madd4=unfused/fused/no
    runtime options:
         -mmadd4=unfused/fused/no

to disable or set madd.fmt type.

For MIPS r6 (TARGET_MIPS8000) and Loongson (TARGET_LOONGSON_3A), 
it always generate fused madd.fmt or maddf.fmt.

diff --git a/gcc/config.gcc b/gcc/config.gcc
index 7afbc54bc78..7176d4484f7 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -3940,7 +3940,7 @@ case "${target}" in
 		;;
 
 	mips*-*-*)
-		supported_defaults="abi arch arch_32 arch_64 float fpu nan fp_32 odd_spreg_32 tune tune_32 tune_64 divide llsc mips-plt synci"
+		supported_defaults="abi arch arch_32 arch_64 float fpu nan fp_32 odd_spreg_32 madd4 tune tune_32 tune_64 divide llsc mips-plt synci"
 
 		case ${with_float} in
 		"" | soft | hard)
@@ -3997,6 +3997,16 @@ case "${target}" in
 			exit 1
 			;;
 		esac
+		
+		case ${with_madd4} in
+		"" | fused | unfused | no)
+			# OK
+			;;
+		*)
+			echo "Unknown madd4 type used in --with-madd4=$with_madd4" 1>&2
+			exit 1
+			;;
+		esac
 
 		case ${with_abi} in
 		"" | 32 | o64 | n32 | 64 | eabi)
@@ -4496,7 +4506,7 @@ 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 nan fp_32 odd_spreg_32 divide llsc mips-plt synci tls"
+all_defaults="abi cpu cpu_32 cpu_64 arch arch_32 arch_64 tune tune_32 tune_64 schedule float mode fpu nan fp_32 odd_spreg_32 madd4 divide llsc mips-plt synci tls"
 for option in $all_defaults
 do
 	eval "val=\$with_"`echo $option | sed s/-/_/g`
diff --git a/gcc/config/mips/mips-opts.h b/gcc/config/mips/mips-opts.h
index 40aa006bc4e..ea1e0ea5310 100644
--- a/gcc/config/mips/mips-opts.h
+++ b/gcc/config/mips/mips-opts.h
@@ -34,6 +34,13 @@ enum mips_ieee_754_setting {
   MIPS_IEEE_754_2008
 };
 
+/* Enumerates the setting of the -mmadd4 option.  */
+enum mips_madd4_setting {
+  MIPS_MADD4_DEFAULT,
+  MIPS_MADD4_UNFUSED,
+  MIPS_MADD4_FUSED,
+  MIPS_MADD4_NO
+};
 /* Enumerates the setting of the -mr10k-cache-barrier option.  */
 enum mips_r10k_cache_barrier_setting {
   R10K_CACHE_BARRIER_NONE,
diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
index bb66c428dd1..e8ca94ac709 100644
--- a/gcc/config/mips/mips.h
+++ b/gcc/config/mips/mips.h
@@ -863,6 +863,7 @@ struct mips_cpu_info {
 	    ":%{!msoft-float:%{!msingle-float:%{!mfp*:%{!mmsa:-mfp%(VALUE)}}}}}" }, \
   {"odd_spreg_32", "%{" OPT_ARCH32 ":%{!msoft-float:%{!msingle-float:" \
 		   "%{!modd-spreg:%{!mno-odd-spreg:-m%(VALUE)}}}}}" }, \
+  {"madd4", "%{!mmadd4=*:-mmadd4=%(VALUE)}" }, \
   {"divide", "%{!mdivide-traps:%{!mdivide-breaks:-mdivide-%(VALUE)}}" }, \
   {"llsc", "%{!mllsc:%{!mno-llsc:-m%(VALUE)}}" }, \
   {"mips-plt", "%{!mplt:%{!mno-plt:-m%(VALUE)}}" }, \
@@ -1056,11 +1057,12 @@ struct mips_cpu_info {
 
 /* ISA has 4 operand fused madd instructions of the form
    'd = [+-] (a * b [+-] c)'.  */
-#define ISA_HAS_FUSED_MADD4	TARGET_MIPS8000
+#define ISA_HAS_FUSED_MADD4	(TARGET_MIPS8000 || TARGET_LOONGSON_3A || (mips_madd4==MIPS_MADD4_FUSED))
 
 /* ISA has 4 operand unfused madd instructions of the form
    'd = [+-] (a * b [+-] c)'.  */
-#define ISA_HAS_UNFUSED_MADD4	(ISA_HAS_FP4 && !TARGET_MIPS8000)
+#define ISA_HAS_UNFUSED_MADD4	(ISA_HAS_FP4 && !TARGET_MIPS8000 && !TARGET_LOONGSON_3A && \
+		(mips_madd4!=MIPS_MADD4_FUSED) && (mips_madd4!=MIPS_MADD4_NO))
 
 /* ISA has 3 operand r6 fused madd instructions of the form
    'c = c [+-] (a * b)'.  */
diff --git a/gcc/config/mips/mips.opt b/gcc/config/mips/mips.opt
index 08dd83e14ce..0d9a6e4362e 100644
--- a/gcc/config/mips/mips.opt
+++ b/gcc/config/mips/mips.opt
@@ -416,6 +416,23 @@ modd-spreg
 Target Report Mask(ODD_SPREG)
 Enable use of odd-numbered single-precision registers.
 
+mmadd4=
+Target RejectNegative Joined Enum(mips_madd4_value) Var(mips_madd4) Init(MIPS_MADD4_DEFAULT)
+-mmadd4=TYPE	Select madd.fmt/msub.fmt type.
+
+Enum
+Name(mips_madd4_value) Type(int)
+Known MIPS madd.fmt type settings (for use with the -mmadd4 options):
+
+EnumValue
+Enum(mips_madd4_value) String(unfused) Value(MIPS_MADD4_UNFUSED)
+
+EnumValue
+Enum(mips_madd4_value) String(fused) Value(MIPS_MADD4_FUSED)
+
+EnumValue
+Enum(mips_madd4_value) String(no) Value(MIPS_MADD4_NO)
+
 mframe-header-opt
 Target Report Var(flag_frame_header_optimization) Optimization
 Optimize frame header.
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index b911d76dd66..e548733537d 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -1338,6 +1338,23 @@ In the absence of this configuration option the default convention is
 the legacy encoding, as when neither of the @option{-mnan=2008} and
 @option{-mnan=legacy} command-line options has been used.
 
+@item --with-madd4=@var{type}
+On MIPS targets, set the default behaivor of madd.fmt/msub.fmt. The
+possibilities for @var{type} are:
+@table @code
+@item unfused
+The madd.fmt/msub.fmt instructions are unfused, as with the 
+@option{-mmadd4=unfused} command-line option.
+@item fused
+The madd.fmt/msub.fmt instructions are fused, as with the 
+@option{-mmadd4=fused} command-line option.
+@item no
+The madd.fmt/msub.fmt are disabled, as with the @option{-mmadd4=no} 
+command-line option.
+@end table
+In the absence of this configuration option the default convention is
+the unfused, while for MIPS r6 and Loongson, the default is fused.
+
 @item --with-divide=@var{type}
 Specify how the compiler should generate code for checking for
 division by zero.  This option is only supported on the MIPS target.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 1096254085f..e88040cdceb 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -19289,6 +19289,29 @@ their trailing significand field being 0.
 The default is @option{-mnan=legacy} unless GCC has been configured with
 @option{--with-nan=2008}.
 
+@item -mmadd4=unfused
+@item -mmadd4=fused
+@item -mmadd4=no
+@opindex mmadd4=unfused
+@opindex mmadd4=fused
+@opindex mmadd4=no
+These options control the type of madd.fmt/msub.fmt, unfused, fused 
+or disabled at all.
+
+The @option{-mmadd4=unfused} option will set type of madd.fmt/msub.fmt
+to be unfused if they are generated.
+
+The @option{-mmadd4=fused} option will set type of madd.fmt/msub.fmt
+to be fused if they are generated.
+
+The @option{-mmadd4=no} option will disable madd.fmt/msub.fmt
+to be generated at all.
+
+The default is @option{-mmadd4=unfused} unless GCC has been configured
+for MIPS r6+ or Loongson. If runtime flags for MIPS r6 or Loongson is
+given, the type will always be `fused', no matter what value 
+@option{-mmadd4=} is.
+
 @item -mllsc
 @itemx -mno-llsc
 @opindex mllsc