PPC: Add soft-float support to interpreter.

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

src/host/buildvm_asm.c

@@ -338,7 +338,7 @@ void emit_asm(BuildCtx *ctx)
 #if !(LJ_TARGET_PS3 || LJ_TARGET_PSVITA)
     fprintf(ctx->fp, "\t.section .note.GNU-stack,\"\"," ELFASM_PX "progbits\n");
 #endif
-#if LJ_TARGET_PPC && !LJ_TARGET_PS3
+#if LJ_TARGET_PPC && !LJ_TARGET_PS3 && !LJ_ABI_SOFTFP
     /* Hard-float ABI. */
     fprintf(ctx->fp, "\t.gnu_attribute 4, 1\n");
 #endif

src/lj_arch.h

@@ -254,6 +254,29 @@
 #else
 #define LJ_ARCH_BITS		32
 #define LJ_ARCH_NAME		"ppc"
+
+#if !defined(LJ_ARCH_HASFPU)
+#if defined(_SOFT_FLOAT) || defined(_SOFT_DOUBLE)
+#define LJ_ARCH_HASFPU		0
+#else
+#define LJ_ARCH_HASFPU		1
+#endif
+#endif
+
+#if !defined(LJ_ABI_SOFTFP)
+#if defined(_SOFT_FLOAT) || defined(_SOFT_DOUBLE)
+#define LJ_ABI_SOFTFP		1
+#else
+#define LJ_ABI_SOFTFP		0
+#endif
+#endif
+#endif
+
+#if LJ_ABI_SOFTFP
+#define LJ_ARCH_NOJIT		1  /* NYI */
+#define LJ_ARCH_NUMMODE		LJ_NUMMODE_DUAL
+#else
+#define LJ_ARCH_NUMMODE		LJ_NUMMODE_DUAL_SINGLE
 #endif
 
 #define LJ_TARGET_PPC		1
@@ -262,7 +285,6 @@
 #define LJ_TARGET_MASKSHIFT	0
 #define LJ_TARGET_MASKROT	1
 #define LJ_TARGET_UNIFYROT	1	/* Want only IR_BROL. */
-#define LJ_ARCH_NUMMODE		LJ_NUMMODE_DUAL_SINGLE
 
 #if LJ_TARGET_CONSOLE
 #define LJ_ARCH_PPC32ON64	1
@@ -415,16 +437,13 @@
 #error "No support for ILP32 model on ARM64"
 #endif
 #elif LJ_TARGET_PPC
-#if defined(_SOFT_FLOAT) || defined(_SOFT_DOUBLE)
-#error "No support for PowerPC CPUs without double-precision FPU"
-#endif
 #if !LJ_ARCH_PPC64 && LJ_ARCH_ENDIAN == LUAJIT_LE
 #error "No support for little-endian PPC32"
 #endif
 #if LJ_ARCH_PPC64
 #error "No support for PowerPC 64 bit mode (yet)"
 #endif
-#ifdef __NO_FPRS__
+#if defined(__NO_FPRS__) && !defined(_SOFT_FLOAT)
 #error "No support for PPC/e500 anymore (use LuaJIT 2.0)"
 #endif
 #elif LJ_TARGET_MIPS32

src/lj_ccall.c

@@ -387,6 +387,24 @@
 #define CCALL_HANDLE_COMPLEXARG \
   /* Pass complex by value in 2 or 4 GPRs. */
 
+#define CCALL_HANDLE_GPR \
+  /* Try to pass argument in GPRs. */ \
+  if (n > 1) { \
+    lua_assert(n == 2 || n == 4);  /* int64_t or complex (float). */ \
+    if (ctype_isinteger(d->info) || ctype_isfp(d->info)) \
+      ngpr = (ngpr + 1u) & ~1u;  /* Align int64_t to regpair. */ \
+    else if (ngpr + n > maxgpr) \
+      ngpr = maxgpr;  /* Prevent reordering. */ \
+  } \
+  if (ngpr + n <= maxgpr) { \
+    dp = &cc->gpr[ngpr]; \
+    ngpr += n; \
+    goto done; \
+  } \
+
+#if LJ_ABI_SOFTFP
+#define CCALL_HANDLE_REGARG  CCALL_HANDLE_GPR
+#else
 #define CCALL_HANDLE_REGARG \
   if (isfp) {  /* Try to pass argument in FPRs. */ \
     if (nfpr + 1 <= CCALL_NARG_FPR) { \
@@ -395,24 +413,16 @@
       d = ctype_get(cts, CTID_DOUBLE);  /* FPRs always hold doubles. */ \
       goto done; \
     } \
-  } else {  /* Try to pass argument in GPRs. */ \
-    if (n > 1) { \
-      lua_assert(n == 2 || n == 4);  /* int64_t or complex (float). */ \
-      if (ctype_isinteger(d->info)) \
-	ngpr = (ngpr + 1u) & ~1u;  /* Align int64_t to regpair. */ \
-      else if (ngpr + n > maxgpr) \
-	ngpr = maxgpr;  /* Prevent reordering. */ \
-    } \
-    if (ngpr + n <= maxgpr) { \
-      dp = &cc->gpr[ngpr]; \
-      ngpr += n; \
-      goto done; \
-    } \
+  } else { \
+    CCALL_HANDLE_GPR \
   }
+#endif
 
+#if !LJ_ABI_SOFTFP
 #define CCALL_HANDLE_RET \
   if (ctype_isfp(ctr->info) && ctr->size == sizeof(float)) \
     ctr = ctype_get(cts, CTID_DOUBLE);  /* FPRs always hold doubles. */
+#endif
 
 #elif LJ_TARGET_MIPS32
 /* -- MIPS o32 calling conventions ---------------------------------------- */
@@ -1080,7 +1090,7 @@ static int ccall_set_args(lua_State *L, CTState *cts, CType *ct,
   }
   if (fid) lj_err_caller(L, LJ_ERR_FFI_NUMARG);  /* Too few arguments. */
 
-#if LJ_TARGET_X64 || LJ_TARGET_PPC
+#if LJ_TARGET_X64 || (LJ_TARGET_PPC && !LJ_ABI_SOFTFP)
   cc->nfpr = nfpr;  /* Required for vararg functions. */
 #endif
   cc->nsp = nsp;

src/lj_ccall.h

@@ -86,9 +86,9 @@ typedef union FPRArg {
 #elif LJ_TARGET_PPC
 
 #define CCALL_NARG_GPR		8
-#define CCALL_NARG_FPR		8
+#define CCALL_NARG_FPR		(LJ_ABI_SOFTFP ? 0 : 8)
 #define CCALL_NRET_GPR		4	/* For complex double. */
-#define CCALL_NRET_FPR		1
+#define CCALL_NRET_FPR		(LJ_ABI_SOFTFP ? 0 : 1)
 #define CCALL_SPS_EXTRA		4
 #define CCALL_SPS_FREE		0
 

src/lj_ccallback.c

@@ -419,6 +419,23 @@ void lj_ccallback_mcode_free(CTState *cts)
 
 #elif LJ_TARGET_PPC
 
+#define CALLBACK_HANDLE_GPR \
+  if (n > 1) { \
+    lua_assert(((LJ_ABI_SOFTFP && ctype_isnum(cta->info)) ||  /* double. */ \
+		ctype_isinteger(cta->info)) && n == 2);  /* int64_t. */ \
+    ngpr = (ngpr + 1u) & ~1u;  /* Align int64_t to regpair. */ \
+  } \
+  if (ngpr + n <= maxgpr) { \
+    sp = &cts->cb.gpr[ngpr]; \
+    ngpr += n; \
+    goto done; \
+  }
+
+#if LJ_ABI_SOFTFP
+#define CALLBACK_HANDLE_REGARG \
+  CALLBACK_HANDLE_GPR \
+  UNUSED(isfp);
+#else
 #define CALLBACK_HANDLE_REGARG \
   if (isfp) { \
     if (nfpr + 1 <= CCALL_NARG_FPR) { \
@@ -427,20 +444,15 @@ void lj_ccallback_mcode_free(CTState *cts)
       goto done; \
     } \
   } else {  /* Try to pass argument in GPRs. */ \
-    if (n > 1) { \
-      lua_assert(ctype_isinteger(cta->info) && n == 2);  /* int64_t. */ \
-      ngpr = (ngpr + 1u) & ~1u;  /* Align int64_t to regpair. */ \
-    } \
-    if (ngpr + n <= maxgpr) { \
-      sp = &cts->cb.gpr[ngpr]; \
-      ngpr += n; \
-      goto done; \
-    } \
+    CALLBACK_HANDLE_GPR \
   }
+#endif
 
+#if !LJ_ABI_SOFTFP
 #define CALLBACK_HANDLE_RET \
   if (ctype_isfp(ctr->info) && ctr->size == sizeof(float)) \
     *(double *)dp = *(float *)dp;  /* FPRs always hold doubles. */
+#endif
 
 #elif LJ_TARGET_MIPS32
 

src/lj_frame.h

@@ -226,7 +226,7 @@ enum { LJ_CONT_TAILCALL, LJ_CONT_FFI_CALLBACK };  /* Special continuations. */
 #define CFRAME_OFS_L		36
 #define CFRAME_OFS_PC		32
 #define CFRAME_OFS_MULTRES	28
-#define CFRAME_SIZE		272
+#define CFRAME_SIZE		(LJ_ARCH_HASFPU ? 272 : 128)
 #define CFRAME_SHIFT_MULTRES	3
 #endif
 #elif LJ_TARGET_MIPS32

src/lj_ircall.h

@@ -287,7 +287,7 @@ 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
+#elif LJ_TARGET_MIPS || LJ_TARGET_PPC
 #define softfp_add __adddf3
 #define softfp_sub __subdf3
 #define softfp_mul __muldf3