I'm trying to write a back-end for an architecture (s12z - the ISA you can download from [1]). This arch accepts indirect memory addresses. That is to say, those of the form (mem (mem (...))) and although my TARGET_LEGITIMATE_ADDRESS function returns true for such addresses, LRA insists on reloading them out of existence. For example, when compiling a code fragment: volatile unsigned char *led = 0x2F2; *led = 1; the ira dump file shows: (insn 7 6 8 2 (set (mem/f/c:PSI (reg/f:PSI 9 y) [3 led+0 S4 A8]) (const_int 754 [0x2f2])) "/home/jmd/MemMem/memmem.c":15:27 96 {movpsi} (nil)) (insn 8 7 14 2 (set (mem/v:QI (mem/f/c:PSI (reg/f:PSI 9 y) [3 led+0 S4 A8]) [0 *led_7+0 S1 A8]) (const_int 1 [0x1])) "/home/jmd/MemMem/memmem.c":16:8 98 {movqi} (nil)) which is a perfectly valid insn, and the most efficient assembler for it is: mov.p #0x2f2, y mov.b #1, [0,y] However the reload dump shows this has been changed to: (insn 7 6 22 2 (set (mem/f/c:PSI (reg/f:PSI 9 y) [3 led+0 S4 A8]) (const_int 754 [0x2f2])) "/home/jmd/MemMem/memmem.c":15:27 96 {movpsi} (nil)) (insn 22 7 8 2 (set (reg:PSI 8 x [22]) (mem/f/c:PSI (reg/f:PSI 9 y) [3 led+0 S4 A8])) "/home/jmd/MemMem/memmem.c":16:8 96 {movpsi} (nil)) (insn 8 22 14 2 (set (mem/v:QI (reg:PSI 8 x [22]) [0 *led_7+0 S1 A8]) (const_int 1 [0x1])) "/home/jmd/MemMem/memmem.c":16:8 98 {movqi} (nil)) and ends up as: mov.p #0x2f2, y mov.p (0,y) x mov.b #1, (0,x) So this wastes a register (which leads to other issues which I don't want to go into in this email). After a lot of debugging I tracked down the part of lra which is doing this reload to the function process_addr_reg at lra-constraints.c:1378 if (! REG_P (reg)) { if (check_only_p) return true; /* Always reload memory in an address even if the target supports such addresses. */ new_reg = lra_create_new_reg_with_unique_value (mode, reg, cl, "address"); before_p = true; } Changing this to if (! REG_P (reg)) { if (check_only_p) return true; return false; } solves my immediate problem. However I imagine there was a reason for doing this reload, and presumably a better way of avoiding it. Can someone explain the reason for this reload, and how I can best ensure that indirect memory operands are left in the compiled code? [1] https://www.nxp.com/docs/en/reference-manual/S12ZCPU_RM_V1.pdf -- Avoid eavesdropping. Send strong encrypted email. PGP Public key ID: 1024D/2DE827B3 fingerprint = 8797 A26D 0854 2EAB 0285 A290 8A67 719C 2DE8 27B3 See http://sks-keyservers.net or any PGP keyserver for public key.