+/* Classes of registers which could be early clobbered in the current
+ insn. */
+
+static varray_type earlyclobber_regclass;
+
+/* This function finds and stores register classes that could be early
+ clobbered in INSN. If any earlyclobber classes are found, the function
+ returns TRUE, in all other cases it returns FALSE. */
+
+static bool
+check_earlyclobber (rtx insn)
+{
+ int opno;
+ bool found = false;
+
+ extract_insn (insn);
+
+ VARRAY_POP_ALL (earlyclobber_regclass);
+ for (opno = 0; opno < recog_data.n_operands; opno++)
+ {
+ char c;
+ bool amp_p;
+ int i;
+ enum reg_class class;
+ const char *p = recog_data.constraints[opno];
+
+ class = NO_REGS;
+ amp_p = false;
+ for (;;)
+ {
+ c = *p;
+ switch (c)
+ {
+ case '=': case '+': case '?':
+ case '#': case '!':
+ case '*': case '%':
+ case 'm': case '<': case '>': case 'V': case 'o':
+ case 'E': case 'F': case 'G': case 'H':
+ case 's': case 'i': case 'n':
+ case 'I': case 'J': case 'K': case 'L':
+ case 'M': case 'N': case 'O': case 'P':
+ case 'X':
+ case '0': case '1': case '2': case '3': case '4':
+ case '5': case '6': case '7': case '8': case '9':
+ /* These don't say anything we care about. */
+ break;
+
+ case '&':
+ amp_p = true;
+ break;
+ case '\0':
+ case ',':
+ if (amp_p && class != NO_REGS)
+ {
+ found = true;
+ for (i = VARRAY_ACTIVE_SIZE (earlyclobber_regclass) - 1;
+ i >= 0; i--)
+ if (VARRAY_INT (earlyclobber_regclass, i) == (int) class)
+ break;
+ if (i < 0)
+ VARRAY_PUSH_INT (earlyclobber_regclass, (int) class);
+ }
+
+ amp_p = false;
+ class = NO_REGS;
+ break;
+
+ case 'r':
+ class = GENERAL_REGS;
+ break;
+
+ default:
+ class = REG_CLASS_FROM_CONSTRAINT (c, p);
+ break;
+ }
+ if (c == '\0')
+ break;
+ p += CONSTRAINT_LEN (c, p);
+ }
+ }
+
+ return found;
+}
+
+/* The function checks that pseudo-register *X has a class
+ intersecting with the class of pseudo-register could be early
+ clobbered in the same insn.
+ This function is a no-op if earlyclobber_regclass is empty. */
+
+static int
+mark_reg_use_for_earlyclobber (rtx *x, void *data ATTRIBUTE_UNUSED)
+{
+ enum reg_class pref_class, alt_class;
+ int i, regno;
+ basic_block bb = data;
+ struct bb_info *bb_info = BB_INFO (bb);
+
+ if (GET_CODE (*x) == REG && REGNO (*x) >= FIRST_PSEUDO_REGISTER)
+ {
+ regno = REGNO (*x);
+ if (bitmap_bit_p (bb_info->killed, regno)
+ || bitmap_bit_p (bb_info->avloc, regno))
+ return 0;
+ pref_class = reg_preferred_class (regno);
+ alt_class = reg_alternate_class (regno);
+ for (i = VARRAY_ACTIVE_SIZE (earlyclobber_regclass) - 1; i >= 0; i--)
+ if (reg_classes_intersect_p (VARRAY_INT (earlyclobber_regclass, i),
+ pref_class)
+ || (VARRAY_INT (earlyclobber_regclass, i) != NO_REGS
+ && reg_classes_intersect_p (VARRAY_INT (earlyclobber_regclass,
+ i),
+ alt_class)))
+ {
+ bitmap_set_bit (bb_info->earlyclobber, regno);
+ break;
+ }
+ }
+ return 0;
+}
+
+/* The function processes all pseudo-registers in *X with the aid of
+ previous function. */
+
+static void
+mark_reg_use_for_earlyclobber_1 (rtx *x, void *data)
+{
+ for_each_rtx (x, mark_reg_use_for_earlyclobber, data);
+}
+