MIPS soft-float, part 1: Add soft-float support to interpreter.

Contributed by Djordje Kovacevic and Stefan Pejic from RT-RK.com.
Sponsored by Cisco Systems, Inc.

src/lj_arch.h

@@ -304,6 +304,13 @@
 #define LJ_TARGET_UNIFYROT	2	/* Want only IR_BROR. */
 #define LJ_ARCH_NUMMODE		LJ_NUMMODE_SINGLE
 
+#if !defined(LJ_ARCH_HASFPU) && defined(__mips_soft_float)
+#define LJ_ARCH_HASFPU		0
+#endif
+#if !defined(LJ_ABI_SOFTFP) && defined(__mips_soft_float)
+#define LJ_ABI_SOFTFP		1
+#endif
+
 #if _MIPS_ARCH_MIPS32R2
 #define LJ_ARCH_VERSION		20
 #else
@@ -386,9 +393,6 @@
 #error "No support for PPC/e500 anymore (use LuaJIT 2.0)"
 #endif
 #elif LJ_TARGET_MIPS
-#if defined(__mips_soft_float)
-#error "No support for MIPS CPUs without FPU"
-#endif
 #if defined(_LP64)
 #error "No support for MIPS64"
 #endif

src/lj_dispatch.h

@@ -14,6 +14,21 @@
 
 #if LJ_TARGET_MIPS
 /* Need our own global offset table for the dreaded MIPS calling conventions. */
+#if LJ_SOFTFP
+extern double __adddf3(double a, double b);
+extern double __subdf3(double a, double b);
+extern double __muldf3(double a, double b);
+extern double __divdf3(double a, double b);
+extern void __ledf2(double a, double b);
+extern double __floatsidf(int32_t a);
+extern int32_t __fixdfsi(double a);
+
+#define SFGOTDEF(_) \
+  _(lj_num2bit) _(sqrt) _(__adddf3) _(__subdf3) _(__muldf3) _(__divdf3) _(__ledf2) \
+  _(__floatsidf) _(__fixdfsi)
+#else
+#define SFGOTDEF(_)
+#endif
 #if LJ_HASJIT
 #define JITGOTDEF(_)	_(lj_trace_exit) _(lj_trace_hot)
 #else
@@ -39,7 +54,8 @@
   _(lj_str_new) _(lj_tab_dup) _(lj_tab_get) _(lj_tab_getinth) _(lj_tab_len) \
   _(lj_tab_new) _(lj_tab_newkey) _(lj_tab_next) _(lj_tab_reasize) \
   _(lj_tab_setinth) _(lj_buf_putstr_reverse) _(lj_buf_putstr_lower) \
-  _(lj_buf_putstr_upper) _(lj_buf_tostr) JITGOTDEF(_) FFIGOTDEF(_)
+  _(lj_buf_putstr_upper) _(lj_buf_tostr) \
+  JITGOTDEF(_) FFIGOTDEF(_) SFGOTDEF(_)
 
 enum {
 #define GOTENUM(name) LJ_GOT_##name,

src/lj_frame.h

@@ -218,6 +218,7 @@ enum { LJ_CONT_TAILCALL, LJ_CONT_FFI_CALLBACK };  /* Special continuations. */
 #define CFRAME_SHIFT_MULTRES	3
 #endif
 #elif LJ_TARGET_MIPS
+#if LJ_ARCH_HASFPU
 #define CFRAME_OFS_ERRF		124
 #define CFRAME_OFS_NRES		120
 #define CFRAME_OFS_PREV		116
@@ -227,6 +228,16 @@ enum { LJ_CONT_TAILCALL, LJ_CONT_FFI_CALLBACK };  /* Special continuations. */
 #define CFRAME_SIZE		112
 #define CFRAME_SHIFT_MULTRES	3
 #else
+#define CFRAME_OFS_ERRF		100
+#define CFRAME_OFS_NRES		96
+#define CFRAME_OFS_PREV		92
+#define CFRAME_OFS_L		88
+#define CFRAME_OFS_PC		44
+#define CFRAME_OFS_MULTRES	16
+#define CFRAME_SIZE		88
+#define CFRAME_SHIFT_MULTRES	3
+#endif
+#else
 #error "Missing CFRAME_* definitions for this architecture"
 #endif
 

src/lj_ircall.h

@@ -270,6 +270,22 @@ LJ_DATA const CCallInfo lj_ir_callinfo[IRCALL__MAX+1];
 #define fp64_f2l __aeabi_f2lz
 #define fp64_f2ul __aeabi_f2ulz
 #endif
+#elif LJ_TARGET_MIPS
+#define softfp_add __adddf3
+#define softfp_sub __subdf3
+#define softfp_mul __muldf3
+#define softfp_div __divdf3
+#define softfp_cmp __ledf2
+#define softfp_i2d __floatsidf
+#define softfp_d2i __fixdfsi
+#define softfp_ui2d __floatunsidf
+#define softfp_f2d __extendsfdf2
+#define softfp_d2ui __fixunsdfsi
+#define softfp_d2f __truncdfsf2
+#define softfp_i2f __floatsisf
+#define softfp_ui2f __floatunsisf
+#define softfp_f2i __fixsfsi
+#define softfp_f2ui __fixunssfsi
 #else
 #error "Missing soft-float definitions for target architecture"
 #endif

src/lj_vm.h

@@ -50,7 +50,7 @@ LJ_ASMF void lj_vm_exit_handler(void);
 LJ_ASMF void lj_vm_exit_interp(void);
 
 /* Internal math helper functions. */
-#if LJ_TARGET_PPC || LJ_TARGET_ARM64
+#if LJ_TARGET_PPC || LJ_TARGET_ARM64 || (LJ_TARGET_MIPS && LJ_ABI_SOFTFP)
 #define lj_vm_floor	floor
 #define lj_vm_ceil	ceil
 #else