tcg/tci: Add TCG_TARGET_CALL_{RET,ARG}_I128

Fill in the parameters for libffi for Int128.
Adjust the interpreter to allow for 16-byte return values.
Adjust tcg_out_call to record the return value length.

Call parameters are no longer all the same size, so we
cannot reuse the same call_slots array for every function.
Compute it each time now, but only fill in slots required
for the call we're about to make.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

tcg/tcg.c

@@ -570,6 +570,22 @@ static GHashTable *helper_table;
 #ifdef CONFIG_TCG_INTERPRETER
 static ffi_type *typecode_to_ffi(int argmask)
 {
+    /*
+     * libffi does not support __int128_t, so we have forced Int128
+     * to use the structure definition instead of the builtin type.
+     */
+    static ffi_type *ffi_type_i128_elements[3] = {
+        &ffi_type_uint64,
+        &ffi_type_uint64,
+        NULL
+    };
+    static ffi_type ffi_type_i128 = {
+        .size = 16,
+        .alignment = __alignof__(Int128),
+        .type = FFI_TYPE_STRUCT,
+        .elements = ffi_type_i128_elements,
+    };
+
     switch (argmask) {
     case dh_typecode_void:
         return &ffi_type_void;
@@ -583,6 +599,8 @@ static ffi_type *typecode_to_ffi(int argmask)
         return &ffi_type_sint64;
     case dh_typecode_ptr:
         return &ffi_type_pointer;
+    case dh_typecode_i128:
+        return &ffi_type_i128;
     }
     g_assert_not_reached();
 }
@@ -613,6 +631,7 @@ static void init_ffi_layouts(void)
         /* Ignoring the return type, find the last non-zero field. */
         nargs = 32 - clz32(typemask >> 3);
         nargs = DIV_ROUND_UP(nargs, 3);
+        assert(nargs <= MAX_CALL_IARGS);
 
         ca = g_malloc0(sizeof(*ca) + nargs * sizeof(ffi_type *));
         ca->cif.rtype = typecode_to_ffi(typemask & 7);

tcg/tci.c

@@ -470,12 +470,9 @@ uintptr_t QEMU_DISABLE_CFI tcg_qemu_tb_exec(CPUArchState *env,
     tcg_target_ulong regs[TCG_TARGET_NB_REGS];
     uint64_t stack[(TCG_STATIC_CALL_ARGS_SIZE + TCG_STATIC_FRAME_SIZE)
                    / sizeof(uint64_t)];
-    void *call_slots[TCG_STATIC_CALL_ARGS_SIZE / sizeof(uint64_t)];
 
     regs[TCG_AREG0] = (tcg_target_ulong)env;
     regs[TCG_REG_CALL_STACK] = (uintptr_t)stack;
-    /* Other call_slots entries initialized at first use (see below). */
-    call_slots[0] = NULL;
     tci_assert(tb_ptr);
 
     for (;;) {
@@ -498,26 +495,26 @@ uintptr_t QEMU_DISABLE_CFI tcg_qemu_tb_exec(CPUArchState *env,
 
         switch (opc) {
         case INDEX_op_call:
-            /*
-             * Set up the ffi_avalue array once, delayed until now
-             * because many TB's do not make any calls. In tcg_gen_callN,
-             * we arranged for every real argument to be "left-aligned"
-             * in each 64-bit slot.
-             */
-            if (unlikely(call_slots[0] == NULL)) {
-                for (int i = 0; i < ARRAY_SIZE(call_slots); ++i) {
-                    call_slots[i] = &stack[i];
+            {
+                void *call_slots[MAX_CALL_IARGS];
+                ffi_cif *cif;
+                void *func;
+                unsigned i, s, n;
+
+                tci_args_nl(insn, tb_ptr, &len, &ptr);
+                func = ((void **)ptr)[0];
+                cif = ((void **)ptr)[1];
+
+                n = cif->nargs;
+                for (i = s = 0; i < n; ++i) {
+                    ffi_type *t = cif->arg_types[i];
+                    call_slots[i] = &stack[s];
+                    s += DIV_ROUND_UP(t->size, 8);
                 }
-            }
-
-            tci_args_nl(insn, tb_ptr, &len, &ptr);
 
-            /* Helper functions may need to access the "return address" */
-            tci_tb_ptr = (uintptr_t)tb_ptr;
-
-            {
-                void **pptr = ptr;
-                ffi_call(pptr[1], pptr[0], stack, call_slots);
+                /* Helper functions may need to access the "return address" */
+                tci_tb_ptr = (uintptr_t)tb_ptr;
+                ffi_call(cif, func, stack, call_slots);
             }
 
             switch (len) {
@@ -542,6 +539,9 @@ uintptr_t QEMU_DISABLE_CFI tcg_qemu_tb_exec(CPUArchState *env,
                  */
                 memcpy(&regs[TCG_REG_R0], stack, 8);
                 break;
+            case 3: /* Int128 */
+                memcpy(&regs[TCG_REG_R0], stack, 16);
+                break;
             default:
                 g_assert_not_reached();
             }

tcg/tci/tcg-target.c.inc

@@ -203,7 +203,7 @@ static const int tcg_target_call_iarg_regs[] = { };
 static TCGReg tcg_target_call_oarg_reg(TCGCallReturnKind kind, int slot)
 {
     tcg_debug_assert(kind == TCG_CALL_RET_NORMAL);
-    tcg_debug_assert(slot >= 0 && slot < 64 / TCG_TARGET_REG_BITS);
+    tcg_debug_assert(slot >= 0 && slot < 128 / TCG_TARGET_REG_BITS);
     return TCG_REG_R0 + slot;
 }
 
@@ -573,11 +573,11 @@ static void tcg_out_call(TCGContext *s, const tcg_insn_unit *func,
 
     if (cif->rtype == &ffi_type_void) {
         which = 0;
-    } else if (cif->rtype->size == 4) {
-        which = 1;
     } else {
-        tcg_debug_assert(cif->rtype->size == 8);
-        which = 2;
+        tcg_debug_assert(cif->rtype->size == 4 ||
+                         cif->rtype->size == 8 ||
+                         cif->rtype->size == 16);
+        which = ctz32(cif->rtype->size) - 1;
     }
     new_pool_l2(s, 20, s->code_ptr, 0, (uintptr_t)func, (uintptr_t)cif);
     insn = deposit32(insn, 0, 8, INDEX_op_call);

tcg/tci/tcg-target.h

@@ -160,10 +160,13 @@ typedef enum {
 #if TCG_TARGET_REG_BITS == 32
 # define TCG_TARGET_CALL_ARG_I32        TCG_CALL_ARG_EVEN
 # define TCG_TARGET_CALL_ARG_I64        TCG_CALL_ARG_EVEN
+# define TCG_TARGET_CALL_ARG_I128       TCG_CALL_ARG_EVEN
 #else
 # define TCG_TARGET_CALL_ARG_I32        TCG_CALL_ARG_NORMAL
 # define TCG_TARGET_CALL_ARG_I64        TCG_CALL_ARG_NORMAL
+# define TCG_TARGET_CALL_ARG_I128       TCG_CALL_ARG_NORMAL
 #endif
+#define TCG_TARGET_CALL_RET_I128        TCG_CALL_RET_NORMAL
 
 #define HAVE_TCG_QEMU_TB_EXEC
 #define TCG_TARGET_NEED_POOL_LABELS