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Re: [PATCH] Fix endianness assumption in LRA


On 09/15/2015 02:39 AM, David Miller wrote:
This was the most glaring case, and would result in LRA crashing
if this code snippet was actually hit on big-endian, since
simplify_gen_subreg() will return NULL in such a case and then
we try to blindly emit a move to 'subreg'.


Vlad, is this OK to commit?
Yes. Thanks, David.

We could use subreg_lowpart_offset for simplify_gen_subreg but for this case it would be just wasting computer cycles.
2015-09-14  David S. Miller  <davem@davemloft.net>

	* lra-constraints.c (simplify_operand_subreg): Do not assume that
	lowpart of a SUBREG has offset zero.

diff --git a/gcc/lra-constraints.c b/gcc/lra-constraints.c
index cdb2695..fc8e43d 100644
--- a/gcc/lra-constraints.c
+++ b/gcc/lra-constraints.c
@@ -1545,7 +1545,7 @@ simplify_operand_subreg (int nop, machine_mode reg_mode)
  	  bool insert_before, insert_after;
PUT_MODE (new_reg, mode);
-          subreg = simplify_gen_subreg (innermode, new_reg, mode, 0);
+          subreg = gen_lowpart_SUBREG (innermode, new_reg);
  	  bitmap_set_bit (&lra_subreg_reload_pseudos, REGNO (new_reg));
insert_before = (type != OP_OUT);


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