+/* Register equivalences. Indexed by register number. */
+typedef struct reg_equivs
+{
+ /* The constant value to which pseudo reg N is equivalent,
+ or zero if pseudo reg N is not equivalent to a constant.
+ find_reloads looks at this in order to replace pseudo reg N
+ with the constant it stands for. */
+ rtx constant;
+
+ /* An invariant value to which pseudo reg N is equivalent.
+ eliminate_regs_in_insn uses this to replace pseudos in particular
+ contexts. */
+ rtx invariant;
+
+ /* A memory location to which pseudo reg N is equivalent,
+ prior to any register elimination (such as frame pointer to stack
+ pointer). Depending on whether or not it is a valid address, this value
+ is transferred to either equiv_address or equiv_mem. */
+ rtx memory_loc;
+
+ /* The address of stack slot to which pseudo reg N is equivalent.
+ This is used when the address is not valid as a memory address
+ (because its displacement is too big for the machine.) */
+ rtx address;
+
+ /* The memory slot to which pseudo reg N is equivalent,
+ or zero if pseudo reg N is not equivalent to a memory slot. */
+ rtx mem;
+
+ /* An EXPR_LIST of REG_EQUIVs containing MEMs with
+ alternate representations of the location of pseudo reg N. */
+ rtx alt_mem_list;
+
+ /* The list of insns that initialized reg N from its equivalent
+ constant or memory slot. */
+ rtx init;
+} reg_equivs_t;
+
+#define reg_equiv_constant(ELT) \
+ (*reg_equivs)[(ELT)].constant
+#define reg_equiv_invariant(ELT) \
+ (*reg_equivs)[(ELT)].invariant
+#define reg_equiv_memory_loc(ELT) \
+ (*reg_equivs)[(ELT)].memory_loc
+#define reg_equiv_address(ELT) \
+ (*reg_equivs)[(ELT)].address
+#define reg_equiv_mem(ELT) \
+ (*reg_equivs)[(ELT)].mem
+#define reg_equiv_alt_mem_list(ELT) \
+ (*reg_equivs)[(ELT)].alt_mem_list
+#define reg_equiv_init(ELT) \
+ (*reg_equivs)[(ELT)].init
+
+extern vec<reg_equivs_t, va_gc> *reg_equivs;