z/OS XL C compiler listing components

The following information describes the components of a C compiler listing. These are available for regular and IPA compilations. Differences in the IPA versions of the listings are noted. Using the IPA link step listing describes IPA-specific listings.

Heading information

The first page of the listing is identified by the product number, the compiler version and release numbers, the name of the data set or z/OS® UNIX file containing the source code, the date and time compilation began (formatted according to the current locale), and the page number.

Note: If the name of the data set or z/OS UNIX file that contains the source code is greater than 32 characters, it is truncated. Only the right-most 32 characters appear in the listing.

Prolog section

The Prolog section provides information about the compile-time library, file identifiers, compiler options, and other items in effect when the compiler was invoked.

All options except those with no default (for example, DEFINE) are shown in the listing. Any problems with the compiler options appear after the body of the Prolog section.

IPA considerations: If you specify IPA suboptions that are irrelevant to the IPA compile step, the Prolog does not display them. If IPA processing is not active, IPA suboptions do not appear in the Prolog. The following information describes the optional parts of the listing and the compiler options that generate them.

Source program

If you specify the SOURCE option, the listing file includes input to the compiler.

Note: If you specify the SHOWINC option, the source listing shows the included text after the #include directives.

Includes section

The compiler generates the Includes section when you use include files, and specify the options SOURCE, LIST, or INLRPT.

Cross-Reference Listing

The XREF option generates a cross-reference table that contains a list of the identifiers from the source program and the line numbers in which they appear.

Structure and Union Maps

You obtain structure and union maps by using the AGGREGATE option. The table shows how each structure and union in the program is mapped. It contains the following:

Name of the structure or union and the elements within the structure or union
Byte offset of each element from the beginning of the structure or union, and the bit offset for unaligned bit data
Length of each element
Total length of each structure, union, and substructure

Messages

If the preprocessor or the compiler detects an error, or the possibility of an error, it generates messages. If you specify the SOURCE compiler option, preprocessor error messages appear immediately after the source statement in error. You can generate your own messages in the preprocessing stage by using the #error preprocessor directive. For information on #error, see the z/OS XL C/C++ Language Reference.

If you specify the compiler options CHECKOUT or INFO(), the compiler will generate informational diagnostic messages.

For more information on the compiler messages, see FLAG | NOFLAG, and z/OS XL C/C++ Messages.

Message Summary

This listing section displays the total number of messages and the number of messages for each severity level.

Inline Report

If you specify the OPTIMIZE and INLINE(,REPORT,,) options, or the OPTIMIZE and INLRPT options, an Inline Report is included in the listing. This report contains an inline summary and a detailed call structure.

Note: No report is produced when your source file contains only one defined subprogram.

The summary contains information such as:

Name of each defined subprogram.
Reason for action on a subprogram:
- The P indicates that #pragma noinline and the COMPACT compiler option are not in effect.
- The F indicates that the subprogram was declared inline, either by #pragma inline for C or the inline keyword for C++.
- The C indicates that the COMPACT compiler option is specified for #pragma_override(FuncName,"OPT(COMPACT,yes)" is specified in the source code.
- The M indicates that C++ routine is an inline member routine.
- The A indicates automatic inlining acted on the subprogram.
- The - indicates there was no reason to inline the subprogram.
Action on a subprogram:
- Subprogram was inlined at least once.
- Subprogram was not inlined because of initial size constraints.
- Subprogram was not inlined because of expansion beyond size constraint.
- Subprogram was a candidate for inlining, but was not inlined.
- Subprogram was a candidate for inlining, but was not referenced.
- The subprogram is directly recursive, or some calls have mismatching parameters.
Note: "Called" and "Calls" in the actions section of the inline report indicate how many times a function has been called or has called other functions, regardless of whether or not the callers or callees have been inlined.
Status of original subprogram after inlining:
- Subprogram is discarded because it is no longer referenced and is defined as static internal.
- Subprogram was not discarded for various reasons :
  - Subprogram is external. (It can be called from outside the compilation unit.)
  - A call to this subprogram remains.
  - Subprogram has its address taken.
Initial relative size of subprogram (in Abstract Code Units (ACU)).
Final relative size of subprogram (in ACUs) after inlining.
Number of calls within the subprogram and the number of these calls that were inlined into subprogram.
Number of times the subprogram is called by others in the compile unit and the number of times the subprogram was inlined.
Mode that is selected and the value of threshold and limit specified for the compilation.

The detailed call structure contains specific information of each subprogram such as:

Subprograms that it calls
Subprograms that call it
Subprograms in which it is inlined

The information can help you to better analyze your program if you want to use the inliner in selective mode.

Inlining may result in additional messages. For example, if inlining a subprogram with automatic storage increases the automatic storage of the subprogram it is being inlined into by more than 4K, a message is generated.

Pseudo Assembly Listing

The LIST compiler option generates a listing of the machine instructions in the object module in a form similar to assembler language.

This Pseudo Assembly listing displays the source statement line numbers and the line number of inlined code to aid you in debugging inlined code.

External Symbol Dictionary

The LIST compiler option generates the External Symbol Dictionary. The External Symbol Dictionary lists the names that the compiler generates for the output object module. It includes address information and size information about each symbol.

External Symbol Cross-Reference

The XREF compiler option generates the External Symbol Cross Reference section. It shows the original name and corresponding mangled name for each symbol.

Storage Offset Listing

If you specify the XREF option, the listing file includes offset information on identifiers.

Static Map

Static Map displays the contents of the @STATIC data area, which holds the file scope read/write static variables. It displays the offset (as a hexadecimal number), the length (as a hexadecimal number), and the names of the objects mapped to @STATIC. Under certain circumstances, the compiler may decide to map other objects to @STATIC. In the example of the listing, the unnamed string "Enter Celsius temperature: \n" is stored in the @STATIC area at offset 48 and its length is 23 (both numbers are in hexadecimal notation), under the name ""12.

If you specify the XREF, IPA (ATTRIBUTE), or IPA (XREF) options, the listing file includes offset information for file scope read/write static variables.