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Re: [PATCH] Improve prepare_shrink_wrap to sink more instructions

On 02/10/14 09:49, Andrew Pinski wrote:
On Fri, Sep 19, 2014 at 1:43 PM, Jeff Law <> wrote:
On 09/15/14 08:33, Jiong Wang wrote:


   thanks, I partially understand your meaning here.

    take the function "ira_implicitly_set_insn_hard_regs" in ira-lives.c
for example,

    when generating address rtl, gcc will automatically generate "const"
operator to prefix
    the address expression, like the following. so a simple CONSTANT_P
check is enough in
    case there is no embedded register.

    (insn 309 310 308 3 (set (reg:DI 44 r15 [orig:94 ivtmp.674 ] [94])
          (const:DI (plus:DI (symbol_ref:DI ("recog_data") [flags 0x40]
<var_decl 0x2b2c2ff91510 recog_data>)
                  (const_int 480 [0x1e0])))) -1

    but for architecture like aarch64, the following instruction
sequences to forming address
    may be generated

(insn 73 14 74 4 (set (reg/f:DI 20 x20 [99])
          (high:DI (symbol_ref:DI ("global_a") [flags 0xc0]  <var_decl
0x7ff755a60900 stats>))) 35 {*movdi_aarch64}
       (expr_list:REG_EQUIV (high:DI (symbol_ref:DI ("global_a") [flags
0xc0]  <var_decl 0x7ff755a60900 stats>))

(insn 17 30 25 5 (set (reg/f:DI 4 x4 [83])
          (lo_sum:DI (reg/f:DI 20 x20 [99])
              (symbol_ref:DI ("global_a") [flags 0xc0]  <var_decl
0x7ff755a60900 stats>))) {add_losym_di}
       (expr_list:REG_EQUIV (symbol_ref:DI ("global_a") [flags 0xc0]
<var_decl 0x7ff755a60900 stats>)

   while CONSTANT_P could not catch the latter lo_sum case, as the
Hmm, it's been ~15 years since I regularly worked on a target that uses
HIGH/LO_SUM, I thought we wrapped the LO_SUM expression inside a CONST as
well, but reading the docs for CONST, that clearly isn't the case.
Could we add a check for lo_sum since it is an RTX_OBJ rather than

thanks, agree, that's exactly what I want to catch, while missed it during the patch re-write. I was been stupid!
anyway, I think we need to solve pr63404, firstly, as it's a correctness regression.


I am testing the patch for that to fix the above issue.  It shows up
with the testcase Jiong added but only with -mabi=ilp32 enabled.

Andrew Pinski

Sorry for that.  Can you (re) send your current patch for this for review?


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