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Oracle Solaris Studio 12.2: C User's Guide
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1.  Introduction to the C Compiler

2.  C-Compiler Implementation-Specific Information

2.1 Constants

2.1.1 Integral Constants

2.1.2 Character Constants

2.2 Linker Scoping Specifiers

2.3 Thread Local Storage Specifier

2.4 Floating Point, Nonstandard Mode

2.5 Labels as Values

2.6 long long Data Type

2.6.1 Printing long long Data Types

2.6.2 Usual Arithmetic Conversions

2.7 Case Ranges in Switch Statements

2.8 Assertions

2.9 Supported Attributes

2.10 Warnings and Errors

2.11 Pragmas

2.11.1 align

2.11.2 c99

2.11.3 does_not_read_global_data

2.11.4 does_not_return

2.11.5 does_not_write_global_data

2.11.6 error_messages

2.11.7 fini

2.11.8 hdrstop

2.11.9 ident

2.11.10 init

2.11.11 inline

2.11.12 int_to_unsigned

2.11.13 MP serial_loop

2.11.14 MP serial_loop_nested

2.11.15 MP taskloop

2.11.16 nomemorydepend

2.11.17 no_side_effect

2.11.18 opt

2.11.19 pack

2.11.20 pipeloop

2.11.21 rarely_called

2.11.22 redefine_extname

2.11.23 returns_new_memory

2.11.24 unknown_control_flow

2.11.25 unroll

2.11.26 warn_missing_parameter_info

2.11.27 weak

2.12 Predefined Names

2.13 Preserving The Value of errno

2.14 Extensions

2.14.1 _Restrict Keyword

2.14.2 __asm Keyword

2.14.3 __inline and __inline__

2.14.4 __builtin_constant_p()


2.15 Environment Variables









2.15.9 TMPDIR

2.16 How to Specify Include Files

2.16.1 Using the -I- Option to Change the Search Algorithm Warnings

2.17 Compiling in Free-Standing Environments

3.  Parallelizing C Code

4.  lint Source Code Checker

5.  Type-Based Alias Analysis

6.  Transitioning to ISO C

7.  Converting Applications for a 64-Bit Environment

8.  cscope: Interactively Examining a C Program

A.  Compiler Options Grouped by Functionality

B.  C Compiler Options Reference

C.  Implementation-Defined ISO/IEC C99 Behavior

D.  Supported Features of C99

E.  Implementation-Defined ISO/IEC C90 Behavior

F.  ISO C Data Representations

G.  Performance Tuning

H.  The Differences Between K&R Solaris Studio C and Solaris Studio ISO C


2.13 Preserving The Value of errno

With -fast, the compiler is free to replace calls to floating point functions with equivalent optimized code that does not set the errno variable. Further, -fast also defines the macro __MATHERR_ERRNO_DONTCARE, which allows the compiler to ignore ensuring the validity of errno. As a result, user code that relies on the value of errno after a floating point function call could produce inconsistent results.

One way around this problem is to avoid compiling such codes with -fast. However, if -fast optimization is required and the code depends on the value of errno being set properly after floating-point library calls, you should compile with the options

-xbuiltin=none -U__MATHERR_ERRNO_DONTCARE -xnolibmopt -xnolibmil

following -fast on the command line to inhibit the compiler from optimizing out such library calls and to insure that errno is handled properly.