diff options
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/lra-constraints.c | 52 |
2 files changed, 44 insertions, 13 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 1fd2aae..bf57485 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2012-10-26 Richard Sandiford <rdsandiford@googlemail.com> + + * lra-constraints.c (process_address): Describe the kinds of address + that we might see. + 2012-10-25 Vladimir Makarov <vmakarov@redhat.com> * lra-int.h (lra_assert): Redefine it gcc_checking_assert. diff --git a/gcc/lra-constraints.c b/gcc/lra-constraints.c index f3729d2..fad1bbd 100644 --- a/gcc/lra-constraints.c +++ b/gcc/lra-constraints.c @@ -2494,8 +2494,23 @@ equiv_address_substitution (struct address *ad, rtx *addr_loc, return change_p; } -/* Major function to make reloads for address in operand NOP. Add to - reloads to the list *BEFORE and *AFTER. We might need to add +/* Major function to make reloads for an address in operand NOP. + The supported cases are: + + 1) an address that existed before LRA started, at which point it must + have been valid. These addresses are subject to elimination and + may have become invalid due to the elimination offset being out + of range. + + 2) an address created by forcing a constant to memory (force_const_to_mem). + The initial form of these addresses might not be valid, and it is this + function's job to make them valid. + + 3) a frame address formed from a register and a (possibly zero) + constant offset. As above, these addresses might not be valid + and this function must make them so. + + Add reloads to the lists *BEFORE and *AFTER. We might need to add reloads to *AFTER because of inc/dec, {pre, post} modify in the address. Return true for any RTL change. */ static bool @@ -2557,9 +2572,19 @@ process_address (int nop, rtx *before, rtx *after) && process_addr_reg (ad.index_reg_loc, before, NULL, INDEX_REG_CLASS)) change_p = true; - /* The address was valid before LRA. We only change its form if the - address has a displacement, so if it has no displacement it must - still be valid. */ + /* There are three cases where the shape of *ADDR_LOC may now be invalid: + + 1) the original address was valid, but either elimination or + equiv_address_substitution applied a displacement that made + it invalid. + + 2) the address is an invalid symbolic address created by + force_const_to_mem. + + 3) the address is a frame address with an invalid offset. + + All these cases involve a displacement, so there is no point + revalidating when there is no displacement. */ if (ad.disp_loc == NULL) return change_p; @@ -2594,9 +2619,8 @@ process_address (int nop, rtx *before, rtx *after) if (ok_p) return change_p; - /* Addresses were legitimate before LRA. So if the address has - two registers than it can have two of them. We should also - not worry about scale for the same reason. */ + /* Any index existed before LRA started, so we can assume that the + presence and shape of the index is valid. */ push_to_sequence (*before); if (ad.base_reg_loc == NULL) { @@ -2611,7 +2635,7 @@ process_address (int nop, rtx *before, rtx *after) rtx insn; rtx last = get_last_insn (); - /* disp => lo_sum (new_base, disp) */ + /* disp => lo_sum (new_base, disp), case (2) above. */ insn = emit_insn (gen_rtx_SET (VOIDmode, new_reg, gen_rtx_HIGH (Pmode, copy_rtx (*ad.disp_loc)))); @@ -2633,14 +2657,15 @@ process_address (int nop, rtx *before, rtx *after) #endif if (code < 0) { - /* disp => new_base */ + /* disp => new_base, case (2) above. */ lra_emit_move (new_reg, *ad.disp_loc); *ad.disp_loc = new_reg; } } else { - /* index * scale + disp => new base + index * scale */ + /* index * scale + disp => new base + index * scale, + case (1) above. */ enum reg_class cl = base_reg_class (mode, as, SCRATCH, SCRATCH); lra_assert (INDEX_REG_CLASS != NO_REGS); @@ -2654,7 +2679,7 @@ process_address (int nop, rtx *before, rtx *after) } else if (ad.index_reg_loc == NULL) { - /* base + disp => new base */ + /* base + disp => new base, cases (1) and (3) above. */ /* Another option would be to reload the displacement into an index register. However, postreload has code to optimize address reloads that have the same base and different @@ -2665,7 +2690,8 @@ process_address (int nop, rtx *before, rtx *after) } else { - /* base + scale * index + disp => new base + scale * index */ + /* base + scale * index + disp => new base + scale * index, + case (1) above. */ new_reg = base_plus_disp_to_reg (mode, as, &ad); *addr_loc = gen_rtx_PLUS (Pmode, new_reg, *ad.index_loc); } |