pls go ahead
Sun
On Fri, Nov 18, 2011 at 10:17 AM, 朱庆 <zqing1...@gmail.com> wrote:
> Hi all,
>
> Can gatekeeper help review for a fix for bug860.
> https://bugs.open64.net/show_bug.cgi?id=860
>
> Problem: case buffer.c at line 60:
> 58 for (i = 0; i < 8; i++)
> 59 {
> 60 struct buffer_head *bh = lru->bhs[i];
>
> when compile at O2:
> 112 # 60 struct buffer_head *bh = lru->bhs[i];
> 113 movq 0(%rax),%r8 # [0] id:56 #kernel
> boot fail at here
>
> %rax come from:
> 72 # 45 lru = &(*(
> 73 # 46 {
> 74 # 47 unsigned long __ptr;
> 75 # 48 __asm__ ("": "=r" (__ptr):"0" ((&per_cpu__bh_lrus)));
> 76 movq $(.data.percpu),%rax # [0] .data.percpu
> 77
> 78 .LBB3_lookup_bh_lru:
> #here should have a move from %rax to %r11
> 79 movq %gs:per_cpu__this_cpu_off(%rip),%r8
> 80 .LBB4_lookup_bh_lru:
> 81 .loc 1 58 0
> 82 # 54 ret__;}
> 83 # 55 ))));}
> 84 # 56 ));
> 85 # 57
> 86 # 58 for (i = 0; i < 8; i++)
> 87 movq 32(%rsp),%r9 # [0] bdev
> 88 movq 40(%rsp),%r10 # [0] block
> 89 .loc 1 54 0
> 90 leaq 0(%r8,%r11,1), %rdx # [0] %r11 is
> never defined before
> 91 xorq %rsi,%rsi # [1]
> 92 xorl %ecx,%ecx # [1]
> 93 movq %r8,.bss+8(%rip) # [1] id:54 anon2+0x0
> 94 .loc 1 58 0
> 95 movq %rdx,%rax # [2]
>
> The root reason is "[ 48, 0] GTN152 :- mov64 GTN151 ; copy" is
> deleted at EBO_Remove_Unused_Ops, but it has use at BB4 and should not be
> deleted.
>
> // Block: 3 Pred: 2 Succ: 4
>
> [ 48, 0] GTN152 :- mov64 GTN151 ; copy //deleted at
> EBO_Remove_Unused_Ops
>
> |||||[53] asm ("mov" "q " "%%" "gs" ":%P" "1" ",%0": "=r" (ret__):"m"
> (per_cpu__this_cpu_off));
>
> [ 53, 0] GTN153 :- asm (sym:per_cpu__this_cpu_off+0) ; side_effects
>
>
> // Block: 4 Pred: 3 Succ: 5
>
> -----------------------------------------------------------------------
>
> |||||[54] ret__;}
>
> [ 54, 0] :- store64 GTN153 GTN34(%rip) (sym:.bss+8) ; WN id:54 anon2+0x0
>
> [ 54, 0] GTN156 :- leax64 GTN153 GTN152 (0x1) (0x0) ;
>
> [ 54, 0] :- store64 GTN156 GTN34(%rip) (sym:.bss+0) ; WN id:55 anon1+0x0
>
> [ 0, 0] GTN157 :- zero32 ;
>
> [ 0, 0] GTN159 :- zero64 ;
>
>
>
> Then found at fun EBO_Remove_Unused_Ops, for TN152, its
> tninfo->redefined_before_block_end is true.
>
> 3370 /* Check for indirect and global references. */
> 3371 if (!tninfo->redefined_before_block_end &&
> 3372 TN_live_out_of(tn, tninfo->in_bb)) goto op_is_needed;
> 3373
>
>
> redefined_before_block_end set to true is because at
> CGTARG_Gen_Dedicated_Subclass_TN,
> TN153 will always return ISA_REGISTER_SUBCLASS_r11 (because the opcode is
> "TOP_asm"), which is the same register for TN152. but infact its fixed
> number of operands or results are 0, and should not have register set info.
>
> 4041 TN* CGTARG_Gen_Dedicated_Subclass_TN( OP* op, int idx, BOOL
> is_result )
> 4042 {
> 4043 const ISA_REGISTER_SUBCLASS subclass = is_result ?
> 4044 OP_result_reg_subclass( op, idx ) : OP_opnd_reg_subclass( op,
> idx );
> 4045 const REGISTER_SET subclass_regs =
> REGISTER_SUBCLASS_members(subclass);
> 4046
> 4047 if( REGISTER_SET_Size(subclass_regs) != 1 ){
> 4048 TN* tn = is_result ? OP_result( op, idx ) : OP_opnd( op, idx );
> 4049 return TN_is_dedicated(tn) ? tn : NULL;
> 4050 }
> 4051
> 4052 const REGISTER reg = REGISTER_SET_Choose(subclass_regs);
> 4053 const ISA_REGISTER_CLASS rc =
> REGISTER_SUBCLASS_register_class(subclass);
> 4054
> 4055 return Build_Dedicated_TN( rc, reg, 0 );
> 4056 }
>
>
> The fix is to add check on the idx, make sure it did not overlap fixed
> opnd or results.
>
>
> Thanks
>
> zhuqing
>
>
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contains a definitive record of customers, application performance,
security threats, fraudulent activity, and more. Splunk takes this
data and makes sense of it. IT sense. And common sense.
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