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* [Bug target/66215] New: [4.8/4.9/5/6 Regression] Wrong after label NOP emission for -mhotpatch
@ 2015-05-20 11:47 marxin at gcc dot gnu.org
  2015-05-20 12:23 ` [Bug target/66215] " marxin at gcc dot gnu.org
                   ` (33 more replies)
  0 siblings, 34 replies; 35+ messages in thread
From: marxin at gcc dot gnu.org @ 2015-05-20 11:47 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66215

            Bug ID: 66215
           Summary: [4.8/4.9/5/6 Regression] Wrong after label NOP
                    emission for -mhotpatch
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
  Target Milestone: ---
            Target: 390-linux

Hi.

Starting from r221381 GCC does not place nops right after function label.
Unfortunately, the problematic patch was also backported to gcc4-[89] and
gcc-5.

$ cat /tmp/s390.c 
static int foo()
{
  return 0;
}

int main(int argc, char **argv)
{
  return foo();
}

$ ./xgcc -B. /tmp/s390.c -mhotpatch=2,3 -o o0.s -S -fno-inline
$ cat o0.s | head ..

.text
        .align  8
        .type   foo, @function
        nopr    %r7     # pre-label NOPs for hotpatch (2 halfwords)
        nopr    %r7
        # alignment for hotpatch
        .align  8
foo:
        # post-label NOPs for hotpatch (3 halfwords)
.LFB0:
        stm     %r11,%r14,44(%r15)
.LCFI0:
        lr      %r11,%r15
.LCFI1:
        nop     0
        nopr    %r7
        lhi     %r1,0
        lr      %r2,%r1
        l       %r4,56(%r11)
        lm      %r11,%r14,44(%r11)
.LCFI2:
        br      %r4

Problem is that patched compiler relies that NOTE_INSN_FUNCTION_BEG is at the
beginning of function. 


/* Inject nops for hotpatching. */
+      for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
+       {
+         if (NOTE_P (insn) && NOTE_KIND (insn) == NOTE_INSN_FUNCTION_BEG)
+           break;
+       }

Problem is that if you use -O2, 256r.sched2 reorders insns after
pro_and_epilogue, where NOTE_INSN_FUNCTION_BEG is placed at the beginning.
On the other hand, if you try -O0, -O1, as the pass is not executed, emission
of NOTE_INSN_FUNCTION_BEG is not reordered.

$ cat s390.c.242r.pro_and_epilogue
foo

(note 1 0 5 NOTE_INSN_DELETED)
(note 5 1 18 2 [bb 2] NOTE_INSN_BASIC_BLOCK)
(insn/f 18 5 19 2 (set (mem:SI (plus:SI (reg/f:SI 15 %r15)
                (const_int 56 [0x38])) [1  S4 A8])
        (reg:SI 14 %r14)) /tmp/s390.c:7 -1
     (nil))
(insn 19 18 20 2 (set (reg:SI 5 %r5)
        (unspec_volatile [
                (const_int 0 [0])
            ] UNSPECV_MAIN_POOL)) /tmp/s390.c:7 -1
     (nil))
(note 20 19 17 2 NOTE_INSN_PROLOGUE_END)
(insn 17 20 4 2 (set (reg:SI 5 %r5)
        (unspec_volatile [
                (const_int 0 [0])
            ] UNSPECV_MAIN_POOL)) 675 {main_pool}
     (nil))
(note 4 17 8 2 NOTE_INSN_FUNCTION_BEG)
(insn 8 4 24 2 (set (reg:SI 1 %r1)
        (mem/u/c:SI (unspec:SI [
                    (symbol_ref/u:SI ("*.LC0") [flags 0x2])
                    (reg:SI 5 %r5)
                ] UNSPEC_LTREF) [2  S4 A32])) /tmp/s390.c:8 68 {*movsi_esa}
     (expr_list:REG_EQUAL (symbol_ref:SI ("foo") [flags 0x3]  <function_decl
0x7fc55997e3e0 foo>)
        (nil)))
(note 24 8 23 2 NOTE_INSN_EPILOGUE_BEG)
(insn/f 23 24 9 2 (set (reg:SI 14 %r14)
        (mem:SI (plus:SI (reg/f:SI 15 %r15)
                (const_int 56 [0x38])) [1  S4 A8])) /tmp/s390.c:9 -1
     (expr_list:REG_CFA_DEF_CFA (plus:SI (reg/f:SI 15 %r15)
            (const_int 96 [0x60]))
        (expr_list:REG_CFA_RESTORE (reg:SI 14 %r14)
            (nil))))
(call_insn/u/j 9 23 10 2 (set (reg:SI 2 %r2)
        (call (mem:QI (reg:SI 1 %r1) [0 foo S1 A8])
            (const_int 0 [0]))) /tmp/s390.c:8 631 {*sibcall_value_br}
     (expr_list:REG_CALL_DECL (symbol_ref:SI ("foo") [flags 0x3] 
<function_decl 0x7fc55997e3e0 foo>)
        (expr_list:REG_EH_REGION (const_int 0 [0])
            (nil)))
    (nil))
(barrier 10 9 16)
(note 16 10 0 NOTE_INSN_DELETED)


$ cat s390.c.256r.sched2
(note 1 0 3 NOTE_INSN_DELETED)
(note 3 1 2 2 [bb 2] NOTE_INSN_BASIC_BLOCK)
(note 2 3 15 2 NOTE_INSN_FUNCTION_BEG)
(insn/f 15 2 16 2 (set (mem:SI (plus:SI (reg/f:SI 15 %r15)
                (const_int 56 [0x38])) [1  S4 A8])
        (reg:SI 14 %r14)) /tmp/s390.c:2 68 {*movsi_esa}
     (expr_list:REG_DEAD (reg:SI 14 %r14)
        (nil)))
(insn 16 15 17 2 (set (reg:SI 5 %r5)
        (unspec_volatile [
                (const_int 0 [0])
            ] UNSPECV_MAIN_POOL)) /tmp/s390.c:2 675 {main_pool}
     (expr_list:REG_UNUSED (reg:SI 5 %r5)
        (nil)))
(note 17 16 14 2 NOTE_INSN_PROLOGUE_END)
(insn 14 17 25 2 (set (reg:SI 5 %r5)
        (unspec_volatile [
                (const_int 0 [0])
            ] UNSPECV_MAIN_POOL)) 675 {main_pool}
     (expr_list:REG_UNUSED (reg:SI 5 %r5)
        (nil)))
(note 25 14 21 2 NOTE_INSN_EPILOGUE_BEG)
(insn 21 25 9 2 (set (reg:SI 4 %r4)
        (mem:SI (plus:SI (reg/f:SI 15 %r15)
                (const_int 56 [0x38])) [1  S4 A8])) /tmp/s390.c:4 68
{*movsi_esa}
     (nil))
(insn 9 21 22 2 (set (reg/i:SI 2 %r2)
        (const_int 0 [0])) /tmp/s390.c:4 68 {*movsi_esa}
     (nil))
(insn/f 22 9 10 2 (set (reg:SI 14 %r14)
        (mem:SI (plus:SI (reg/f:SI 15 %r15)
                (const_int 56 [0x38])) [1  S4 A8])) /tmp/s390.c:4 68
{*movsi_esa}
     (expr_list:REG_CFA_DEF_CFA (plus:SI (reg/f:SI 15 %r15)
            (const_int 96 [0x60]))
        (expr_list:REG_CFA_RESTORE (reg:SI 14 %r14)
            (nil))))
(insn 10 22 23 2 (use (reg/i:SI 2 %r2)) /tmp/s390.c:4 -1
     (nil))
(jump_insn 23 10 24 2 (parallel [
            (return)
            (use (reg:SI 4 %r4))
        ]) /tmp/s390.c:4 681 {*return}
     (expr_list:REG_DEAD (reg:SI 4 %r4)
        (nil))
 -> return)

So the question is if NOTE_INSN_FUNCTION_BEG is not correctly located by
pro_and_epilogue, or we should fix NOP emission?

Thanks,
Martin


^ permalink raw reply	[flat|nested] 35+ messages in thread
end of thread, other threads:[~2015-06-22 12:09 UTC | newest]

Thread overview: 35+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-05-20 11:47 [Bug target/66215] New: [4.8/4.9/5/6 Regression] Wrong after label NOP emission for -mhotpatch marxin at gcc dot gnu.org
2015-05-20 12:23 ` [Bug target/66215] " marxin at gcc dot gnu.org
2015-05-20 13:48 ` jakub at gcc dot gnu.org
2015-05-20 14:21 ` krebbel at gcc dot gnu.org
2015-05-21  6:05 ` vogt at linux dot vnet.ibm.com
2015-05-21  7:59 ` jakub at gcc dot gnu.org
2015-05-21  8:58 ` rguenth at gcc dot gnu.org
2015-05-22  8:36 ` vogt at linux dot vnet.ibm.com
2015-05-22  8:43 ` jakub at gcc dot gnu.org
2015-05-22 10:14 ` vogt at linux dot vnet.ibm.com
2015-05-22 10:43 ` jakub at gcc dot gnu.org
2015-05-22 11:35 ` vogt at linux dot vnet.ibm.com
2015-05-22 12:22 ` vogt at linux dot vnet.ibm.com
2015-05-22 12:43 ` jakub at gcc dot gnu.org
2015-05-22 13:19 ` vogt at linux dot vnet.ibm.com
2015-05-22 13:35 ` vogt at linux dot vnet.ibm.com
2015-05-22 13:41 ` jakub at gcc dot gnu.org
2015-05-22 13:58 ` vogt at linux dot vnet.ibm.com
2015-05-25 13:04 ` mbenes at suse dot cz
2015-05-25 13:17 ` jakub at gcc dot gnu.org
2015-05-26  5:42 ` vogt at linux dot vnet.ibm.com
2015-05-26  7:05 ` jakub at gcc dot gnu.org
2015-05-26 10:49 ` vogt at linux dot vnet.ibm.com
2015-05-26 12:39 ` jakub at gcc dot gnu.org
2015-05-29  8:51 ` vogt at linux dot vnet.ibm.com
2015-05-29 10:59 ` krebbel at gcc dot gnu.org
2015-05-29 10:59 ` vogt at linux dot vnet.ibm.com
2015-05-29 14:27 ` krebbel at gcc dot gnu.org
2015-05-29 22:58 ` jakub at gcc dot gnu.org
2015-06-01 11:18 ` vogt at linux dot vnet.ibm.com
2015-06-01 11:20 ` jakub at gcc dot gnu.org
2015-06-01 11:26 ` krebbel at gcc dot gnu.org
2015-06-01 11:28 ` krebbel at gcc dot gnu.org
2015-06-01 11:30 ` krebbel at gcc dot gnu.org
2015-06-22 12:09 ` rguenth at gcc dot gnu.org

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