Fixes are available
March 2013 PTF for XL C for AIX, V12.1
March 2013 PTF for XL C/C++ for AIX, V12.1
XL C/C++ for AIX Fix Pack 4 (June 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 5 (September 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 7 (January 2014 PTF) for 12.1
XL C for AIX Fix Pack 8 (March 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 8 (March 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 11 (February 2015 PTF) for 12.1
XL C for AIX Fix Pack 12 (May 2015 PTF) for 12.1
XL C/C++ for AIX Fix Pack 12 (May 2015 PTF) for 12.1
XL C/C++ for AIX Fix Pack 13 (August 2015 Update) for 12.1
XL C/C++ for AIX Fix Pack 14 (December 2015 Update) for 12.1
XL C for AIX Fix Pack 15 (April 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 15 (April 2016 Update) for 12.1
XL C for AIX Fix Pack 16 (July 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 16 (July 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 17 (November 2016 Update) for 12.1
XL C for AIX Fix Pack 17 (November 2016 Update) for 12.1
XL C for AIX Fix Pack 18 (February 2017 Update) for 12.1
XL C/C++ for AIX Fix Pack 18 (February 2017 Update) for 12.1
XL C for AIX Fix Pack 19 (August 2017 Update) for 12.1
XL C/C++ for AIX Fix Pack 19 (August 2017 Update) for 12.1
XL C for AIX Fix Pack 20 (March 2018 Update) for 12.1
XL C/C++ for AIX Fix Pack 20 (March 2018 Update) for 12.1
XL C for AIX Fix Pack 4 (June 2013 PTF) for 12.1
XL C for AIX Fix Pack 5 (September 2013 PTF) for 12.1
XL C for AIX Fix Pack 6 (December 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 6 (December 2013 PTF) for 12.1
XL C for AIX Fix Pack 7 (January 2014 PTF) for 12.1
XL C for AIX Fix Pack 9 (July 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 9 (July 2014 PTF) for 12.1
XL C for AIX Fix Pack 10 (October 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 10 (October 2014 PTF) for 12.1
XL C for AIX Fix Pack 11 (February 2015 PTF) for 12.1
XL C for AIX Fix Pack 13 (August 2015 Update) for 12.1
XL C for AIX Fix Pack 14 (December 2015 Update) for 12.1
XL C/C++ for AIX Fix Pack 21 (January 2019 Update) for 12.1
XL C for AIX Fix Pack 21 (January 2019 Update) for 12.1
APAR status
Closed as program error.
Error description
The counter in the for loop goes past its boundaries when compiling with -qipa and causes an incorrect output at runtime. The issue goes away if you remove -qipa from the compile line. ===== COMPILE COMMAND: xlC_r -o tc test.c -O -q64 -qipa ===== TESTCASE: $ cat test.c #include <stdio.h> int main() { unsigned int ctr=6; unsigned int stop = (unsigned int)-1; unsigned int start = 5; printf("start=%u ; stop=%u\n",start,stop); for(ctr = start ; ctr != stop ; --ctr) { printf("ctr=%u\n",ctr); if (ctr>start) { printf("Shouldn't get here\n"); exit(1); } } } $ ===== ACTUAL OUTPUT: $ ./tc start=5 ; stop=4294967295 ctr=5 ctr=4 ctr=3 ctr=2 ctr=1 ctr=0 ctr=4294967295 Shouldn't get here $ ===== EXPECTED OUTPUT: $ ./tc start=5 ; stop=4294967295 ctr=5 ctr=4 ctr=3 ctr=2 ctr=1 ctr=0 $
Local fix
Compile with -qstrict_induction. Although, you may need to monitor the runtime performance when using this option.
Problem summary
USERS AFFECTED: Users using -qhot=level=0 or above may be affected by this issue. PROBLEM DESCRIPTION: When -qhot=level=0 or higher is used, users may encounter incorrect output due to an internal induction variable overflow.
Problem conclusion
The fix consists of detecting a loop normalization opportunity where the induction variable overflows; so that users do not have to face a performance impact of using -qstrict_induction.
Temporary fix
Comments
APAR Information
APAR number
IV37956
Reported component name
XL C FOR AIX
Reported component ID
5725C7100
Reported release
C10
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2013-03-12
Closed date
2013-03-12
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:
Fix information
Fixed component name
XL C FOR AIX
Fixed component ID
5725C7100
Applicable component levels
Document Information
Modified date:
03 October 2021