arch/mips: add support for MIPS NaN

MIPS supports two different NaN encodings, legacy and 2008. Information
about MIPS NaN encodings can be found here:

  https://sourceware.org/binutils/docs/as/MIPS-NaN-Encodings.html

NaN legacy is the only option available for R2 cores and older.
NaN 2008 is the only option available for R6 cores.
R5 cores can have either NaN legacy or NaN 2008, depending on the
implementation. So, if the user selects a generic R5 target architecture
variant, we show a choice menu with both options available. For well
known R5 cores we directly select the NaN enconding they use.

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

arch/Config.in

@@ -264,6 +264,9 @@ config BR2_GCC_TARGET_ARCH
 config BR2_GCC_TARGET_ABI
 	string
 
+config BR2_GCC_TARGET_NAN
+	string
+
 config BR2_GCC_TARGET_CPU
 	string
 

arch/Config.in.mips

@@ -1,20 +1,26 @@
 # mips default CPU ISAs
 config BR2_MIPS_CPU_MIPS32
 	bool
+	select BR2_MIPS_NAN_LEGACY
 config BR2_MIPS_CPU_MIPS32R2
 	bool
+	select BR2_MIPS_NAN_LEGACY
 config BR2_MIPS_CPU_MIPS32R5
 	bool
 config BR2_MIPS_CPU_MIPS32R6
 	bool
+	select BR2_MIPS_NAN_2008
 config BR2_MIPS_CPU_MIPS64
 	bool
+	select BR2_MIPS_NAN_LEGACY
 config BR2_MIPS_CPU_MIPS64R2
 	bool
+	select BR2_MIPS_NAN_LEGACY
 config BR2_MIPS_CPU_MIPS64R5
 	bool
 config BR2_MIPS_CPU_MIPS64R6
 	bool
+	select BR2_MIPS_NAN_2008
 
 choice
 	prompt "Target Architecture Variant"
@@ -51,6 +57,7 @@ config BR2_mips_m5150
 	bool "M5150"
 	depends on !BR2_ARCH_IS_64
 	select BR2_MIPS_CPU_MIPS32R5
+	select BR2_MIPS_NAN_2008
 config BR2_mips_m6250
 	bool "M6250"
 	depends on !BR2_ARCH_IS_64
@@ -59,6 +66,7 @@ config BR2_mips_p5600
 	bool "P5600"
 	depends on !BR2_ARCH_IS_64
 	select BR2_MIPS_CPU_MIPS32R5
+	select BR2_MIPS_NAN_2008
 config BR2_mips_xburst
 	bool "XBurst"
 	depends on !BR2_ARCH_IS_64
@@ -126,6 +134,33 @@ config BR2_MIPS_SOFT_FLOAT
 	  floating point functions, then everything will need to be
 	  compiled with soft floating point support (-msoft-float).
 
+config BR2_MIPS_NAN_LEGACY
+	bool
+
+config BR2_MIPS_NAN_2008
+	bool
+
+choice
+	prompt "Target NaN"
+	depends on BR2_mips_32r5 || BR2_mips_64r5
+	default BR2_MIPS_ENABLE_NAN_2008
+	help
+	  NaN encoding to be used
+
+config BR2_MIPS_ENABLE_NAN_LEGACY
+	bool "legacy"
+	select BR2_MIPS_NAN_LEGACY
+
+config BR2_MIPS_ENABLE_NAN_2008
+	bool "2008"
+	depends on !BR2_MIPS_SOFT_FLOAT
+	select BR2_MIPS_NAN_2008
+endchoice
+
+config BR2_GCC_TARGET_NAN
+	default "legacy"	if BR2_MIPS_NAN_LEGACY
+	default "2008"		if BR2_MIPS_NAN_2008
+
 config BR2_ARCH
 	default "mips"		if BR2_mips
 	default "mipsel"	if BR2_mipsel

package/gcc/gcc.mk

@@ -210,6 +210,9 @@ endif
 ifneq ($(call qstrip,$(BR2_GCC_TARGET_ABI)),)
 HOST_GCC_COMMON_CONF_OPTS += --with-abi=$(BR2_GCC_TARGET_ABI)
 endif
+ifneq ($(call qstrip,$(BR2_GCC_TARGET_NAN)),)
+HOST_GCC_COMMON_CONF_OPTS += --with-nan=$(BR2_GCC_TARGET_NAN)
+endif
 ifneq ($(call qstrip,$(BR2_GCC_TARGET_CPU)),)
 ifneq ($(call qstrip,$(BR2_GCC_TARGET_CPU_REVISION)),)
 HOST_GCC_COMMON_CONF_OPTS += --with-cpu=$(call qstrip,$(BR2_GCC_TARGET_CPU)-$(BR2_GCC_TARGET_CPU_REVISION))
@@ -260,6 +263,7 @@ HOST_GCC_COMMON_WRAPPER_TARGET_CPU := $(call qstrip,$(BR2_GCC_TARGET_CPU)-$(BR2_
 endif
 HOST_GCC_COMMON_WRAPPER_TARGET_ARCH := $(call qstrip,$(BR2_GCC_TARGET_ARCH))
 HOST_GCC_COMMON_WRAPPER_TARGET_ABI := $(call qstrip,$(BR2_GCC_TARGET_ABI))
+HOST_GCC_COMMON_WRAPPER_TARGET_NAN := $(call qstrip,$(BR2_GCC_TARGET_NAN))
 HOST_GCC_COMMON_WRAPPER_TARGET_FPU := $(call qstrip,$(BR2_GCC_TARGET_FPU))
 HOST_GCC_COMMON_WRAPPER_TARGET_FLOAT_ABI := $(call qstrip,$(BR2_GCC_TARGET_FLOAT_ABI))
 HOST_GCC_COMMON_WRAPPER_TARGET_MODE := $(call qstrip,$(BR2_GCC_TARGET_MODE))
@@ -273,6 +277,9 @@ endif
 ifneq ($(HOST_GCC_COMMON_WRAPPER_TARGET_ABI),)
 HOST_GCC_COMMON_TOOLCHAIN_WRAPPER_ARGS += -DBR_ABI='"$(HOST_GCC_COMMON_WRAPPER_TARGET_ABI)"'
 endif
+ifneq ($(HOST_GCC_COMMON_WRAPPER_TARGET_NAN),)
+HOST_GCC_COMMON_TOOLCHAIN_WRAPPER_ARGS += -DBR_NAN='"$(HOST_GCC_COMMON_WRAPPER_TARGET_NAN)"'
+endif
 ifneq ($(HOST_GCC_COMMON_WRAPPER_TARGET_FPU),)
 HOST_GCC_COMMON_TOOLCHAIN_WRAPPER_ARGS += -DBR_FPU='"$(HOST_GCC_COMMON_WRAPPER_TARGET_FPU)"'
 endif

package/uclibc/Config.in

@@ -123,8 +123,8 @@ config BR2_UCLIBC_MIPS_ABI
 
 config BR2_UCLIBC_MIPS_NAN
 	string
-	default "LEGACY" if BR2_MIPS_CPU_MIPS32 || BR2_MIPS_CPU_MIPS64
+	default "LEGACY" if BR2_MIPS_NAN_LEGACY
-	default "2008" if BR2_MIPS_CPU_MIPS32R6 || BR2_MIPS_CPU_MIPS64R6
+	default "2008" if BR2_MIPS_NAN_2008
 	depends on BR2_UCLIBC_TARGET_ARCH = "mips"
 
 config BR2_UCLIBC_SH_TYPE

toolchain/toolchain-external/pkg-toolchain-external.mk

@@ -154,6 +154,7 @@ CC_TARGET_CPU_ := $(call qstrip,$(BR2_GCC_TARGET_CPU)-$(BR2_GCC_TARGET_CPU_REVIS
 endif
 CC_TARGET_ARCH_ := $(call qstrip,$(BR2_GCC_TARGET_ARCH))
 CC_TARGET_ABI_ := $(call qstrip,$(BR2_GCC_TARGET_ABI))
+CC_TARGET_NAN_ := $(call qstrip,$(BR2_GCC_TARGET_NAN))
 CC_TARGET_FPU_ := $(call qstrip,$(BR2_GCC_TARGET_FPU))
 CC_TARGET_FLOAT_ABI_ := $(call qstrip,$(BR2_GCC_TARGET_FLOAT_ABI))
 CC_TARGET_MODE_ := $(call qstrip,$(BR2_GCC_TARGET_MODE))
@@ -176,6 +177,10 @@ ifneq ($(CC_TARGET_ABI_),)
 TOOLCHAIN_EXTERNAL_CFLAGS += -mabi=$(CC_TARGET_ABI_)
 TOOLCHAIN_EXTERNAL_TOOLCHAIN_WRAPPER_ARGS += -DBR_ABI='"$(CC_TARGET_ABI_)"'
 endif
+ifneq ($(CC_TARGET_NAN_),)
+TOOLCHAIN_EXTERNAL_CFLAGS += -mnan=$(CC_TARGET_NAN_)
+TOOLCHAIN_EXTERNAL_TOOLCHAIN_WRAPPER_ARGS += -DBR_NAN='"$(CC_TARGET_NAN_)"'
+endif
 ifneq ($(CC_TARGET_FPU_),)
 TOOLCHAIN_EXTERNAL_CFLAGS += -mfpu=$(CC_TARGET_FPU_)
 TOOLCHAIN_EXTERNAL_TOOLCHAIN_WRAPPER_ARGS += -DBR_FPU='"$(CC_TARGET_FPU_)"'

toolchain/toolchain-wrapper.c

@@ -51,6 +51,9 @@ static char *predef_args[] = {
 #ifdef BR_ABI
 	"-mabi=" BR_ABI,
 #endif
+#ifdef BR_NAN
+	"-mnan=" BR_NAN,
+#endif
 #ifdef BR_FPU
 	"-mfpu=" BR_FPU,
 #endif