IV28620: INEFFICIENT STRUCT/UNION INIT OF MEMBER

Fixes are available

APAR status

Closed as program error.

Error description

xlC initializes struct and union member with inefficient loads
from constant area while load immediate could be used to
create the values that are stored to the struct/union.


===== COMPILE COMMAND:
xlC -q64 -O2 -qlist -c test.C


===== TESTCASE:
$ cat test.C
struct  sqlz_value
{
   unsigned short type;
   union
   {
      unsigned short clen;
      struct
      {
         unsigned char m;
         unsigned char n;
      } dlen;
   } len;
   unsigned char *data;
};

extern "C" void intToDec(struct sqlz_value *dec, int i);

extern "C" void init(int i)
{
   struct sqlz_value promote;
   promote.type = 2;
   promote.len.dlen.m = 11;
   promote.len.dlen.n = 0;
   intToDec(&promote, i);
}
$


When looking at the provided test case, only the 0 gets loaded
using li.
But for 11, two loads from constant area are used.

 18|                                  PROC      i,gr3
    0| 000000 mfspr    7C0802A6   1     LFLR      gr0=lr
    0| 000004 ld       E8A20008   1     L8
gr5=.+CONSTANT_AREA(gr2,0)
    0| 000008 stdu     F821FF81   1     ST8U
gr1,#stack(gr1,-128)=gr1
   24| 00000C extsw    7C6407B4   1     EXTS4     gr4=gr3
   24| 000010 addi     38610070   1     AI        gr3=gr1,112
    0| 000014 std      F8010090   1     ST8
#stack(gr1,144)=gr0
   23| 000018 addi     38000000   1     LI        gr0=0
   23| 00001C stb      98010073   1     ST1Z
<a1:d115:l1>(gr1,115)=gr0
   22| 000020 lhz      A0050000   1     L2Z
gr0=+CONSTANT_AREA(gr5,0) <---- here
   22| 000024 lbz      88A50002   1     L1Z
gr5=+CONSTANT_AREA(gr5,2) <---- here
   22| 000028 sth      B0010070   1     ST2Z
promote.|type@0#11|m@2#12_1(gr1,112)=gr0
   22| 00002C stb      98A10072   1     ST1Z
promote.|type@0#11|m@2#12_1(gr1,114)=gr5
   24| 000030 bl       4BFFFFD1   1     CALL
intToDec,2,promote",gr3,gr4,#ProcAlias",intToDec",fcr",gr1,cr[01
567]",gr0",gr3"-gr12",fp0"-fp13",mq",lr",fcr",xer",fsr",ca",ctr"
   24| 000034 ori      60000000   1
   25| 000038 ld       E9810090   1     L8
gr12=#stack(gr1,144)
   25| 00003C addi     38210080   1     AI        gr1=gr1,128
   25| 000040 mtspr    7D8803A6   1     LLR       lr=gr12
   25| 000044 bclr     4E800020   1     BA        lr

Local fix

```
n/a
```

Problem summary

```
TBD
```

Problem conclusion

```
TBD
```

Temporary fix

Comments

APAR Information

APAR number
IV28620
Reported component name
XL C/C++ FOR AI
Reported component ID
5725C7200
Reported release
C10
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2012-09-25
Closed date
2012-11-09
Last modified date
2013-03-13

APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:

LI77123

Fix information

Fixed component name
XL C FOR AIX
Fixed component ID
5725C7100

Applicable component levels

RC10 PSY UP
C

[{"Business Unit":{"code":"BU048","label":"IBM Software"},"Product":{"code":"SSGH2K","label":"XL C for AIX"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"12.1","Edition":"","Line of Business":{"code":"LOB73","label":"Power TPS"}}]

Document Information

Modified date:
21 August 2024

Tips

IV28620: INEFFICIENT STRUCT/UNION INIT OF MEMBER

Fixes are available

Subscribe

APAR status

Closed as program error.

Error description

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

APAR number

Reported component name

Reported component ID

Reported release

Status

PE

HIPER

Special Attention

Submitted date

Closed date

Last modified date

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name

Fixed component ID

Applicable component levels

RC10 PSY UP

Document Information

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