Documentation errata for IBM XL C for AIX, V10.1

Preventive Service Planning


Abstract

This page contains corrections and additions to the product documentation shipped with IBM XL C for AIX, V10.1.

Content

Language Reference
The following corrections and additions apply to the IBM XL C for AIX, V10.1 Language Reference:

Chapter: The IBM XL C language extensions

In C99 features as extensions to C89:

One of the possible values for -qlanglvl is specified as "stcd99".

It should read "stdc99".

Compiler Reference
The following corrections and additions apply to the IBM XL C for AIX, V10.1 Compiler Reference:

Chapter: Configuring compiler defaults

Section: Setting environment variables

Topic: Environment variables for parallel processing

In "XLSMPOPTS", the description of stack=num should read:

stack=num

Specifies the largest amount of space in bytes (num) that a thread's stack needs. The default value for num is 4194304.

Set num so it is within the acceptable upper limit. num can be up to 256 MB for 32-bit mode, or up to the limit imposed by system resources for 64-bit mode. An application that exceeds the upper limit may cause a segmentation fault.


Chapter: Compiler options reference

Section: Individual option descriptions

Topic: -qdfp
The following new information is added:

Note: To use decimal floating-point types and literals, you must also enable specific code in header files by defining the __STDC_WANT_DEC_FP__ macro at compiler time. See Examples.

Examples
To compile myprogram.c so that the compiler supports decimal floating-point types and literals, enter:
xlc myprogram.c -qarch=pwr7 -qdfp -D__STDC_WANT_DEC_FP__

Topic: -qfloat
-qfloat=fltint | nofltint option
The following new information is added:

If -qarch is set to a processor that has an instruction to convert from floating point to integer, that instruction will be used regardless of the [no]fltint setting. This conversion also applies to all PowerPC processors in 64-bit mode.

  • -qfloat=dfpemulate:nofenv:nofltint:fold: nohscmplx:nohsflt:nohssnglmaf:nonans:norelax:rndsngl:rngchk:norrm:norsqrt:single:nospnans

Should read:
  • -qfloat=dfpemulate:nofenv:nofltint:fold: nohscmplx:nohsflt:nohssngl:maf:nonans:norelax:rndsngl:rngchk:norrm:norsqrt:single:nospnans

Topic: -qinfo
-qinfo=private suboption
In the syntax diagram the suboption -qinfo=private has no affect when specified and should be removed. Instead, use the -qreport option to report compiler-driven automatic parallelization cases; user parallelization cases are not reported.

Chapter: Compiler pragmas reference

Section: Individual pragmas descriptions

Topic: #pragma reg_killed_by

fs
    Floating-point and status control register

Should read:

fsr
    Floating-point and status control register


Chapter: Compiler predefined macros

Section: Macros indicating the XL C compiler product

The following two predefined macros should be added in the table:

Predefined macro name Description Predefined value
__xlC__ Indicates the VR level of the XL C and XL C++ compilers in hexadecimal format. Using the XL C compiler also automatically defines this macro. A four-digit hexadecimal integer in the format 0xVVRR, where:

V
    Represents the version number
R
    Represents the release number

In XL C/C++ V10.1, the value of the macro is 0x0a01.
__xlC_ver__ Indicates the MF level of the XL C and XL C++ compilers in hexadecimal format. Using the XL C compiler also automatically defines this macro. An eight-digit hexadecimal integer in the format 0x0000MMFF, where:

M
    Represents the modification number
F
    Represents the fix level

In XL C/C++ V10.1, PTF 10.1.0.3, the value of the macro is 0x00000003.


Optimization and Programming Guide
The following correction applies to the IBM XL C for AIX, V10.1 Optimization and Programming Guide:

Chapter: Handling floating-point operations

Topic: Compiling a decimal floating-point program

The following text:

If you are using decimal floating-point formats in your programs, use the -qdfp option when you compile them. For example, to compile the following Hello World program dfp_hello.c, the compiler invocation is:
xlc -qdfp dfp_hello.c

Should read:

If you are using decimal floating-point formats in your programs, use the -qdfp option and define the __STDC_WANT_DEC_FP__ macro when you compile them.

For example, to compile dfp_hello.c, use the following compiler invocation:
xlc dfp_hello.c -qdfp -qarch=pwr7 -D__STDC_WANT_DEC_FP__


Chapter: Parallelizing your programs

Topic: Shared and private variables in a parallel environment

The following text:

The compiler can privatize some shared variables if it is possible to do so without changing the semantics of the program. For example, if each loop iteration uses a unique value of a shared variable, that variable can be privatized. Privatized shared variables are reported by the -qinfo=private option. Use critical sections to synchronize access to all shared variables not listed in this report.

Should read:

The compiler can privatize some shared variables if it is possible to do so without changing the semantics of the program. For example, if each loop iteration uses a unique value of a shared variable, that variable can be privatized. Privatized shared variables are reported by the -qreport option. Use critical sections to synchronize access to all shared variables not listed in this report.

For information on how to list which shared variables are privatized by the compiler, see:
How to list privatized shared variables in an automatic parallel loop

Related information

README Updates for IBM XL C for AIX V10.1

Cross reference information
Segment Product Component Platform Version Edition
Software Development XL C for AIX

Rate this page:

(0 users)Average rating

Document information


More support for:

XL C for AIX
Documentation

Software version:

10.1

Operating system(s):

AIX

Reference #:

1313065

Modified date:

2013-11-20

Translate my page

Machine Translation

Content navigation