/Zi Causes Code Motion Optimization Suppression

ID: Q32892

6.00 6.00a 6.00ax 7.00 | 6.00 6.00a | 1.00 1.50

MS-DOS                 | OS/2       | WINDOWS

kbtool

The information in this article applies to:

 The Microsoft C/C++ Compiler (CL.EXE), supplied with:
  - Microsoft C for MS-DOS, versions 6.0, 6.0a, and 6.0ax
  - Microsoft C for OS/2, versions 6.0, and 6.0a
  - Microsoft C/C++ for MS-DOS, version 7.0
  - Microsoft Visual C++ for Windows, version 1.0 and 1.5

SUMMARY

In Microsoft C, using the full optimizing compiler with /Zi and no other switches causes certain code motion optimizations to be suppressed (that is, the code generated for a program with the defaults and with /Zi may differ).

You can override this default behavior by explicitly specifying the default optimizations on the command line. For example, you can compile with the following command line to get the same code with or without /Zi:

   For C versions 6.0, 6.0a, and 6.0ax:

      cl /Zi /Ot file.c

   For C/C++ version 7.0 and Visual C++ 1.0 and 1.5:

      cl /f- /Zi /Ot file.c

However, it is recommended that you compile with the /Od option if you will be debugging the code, to suppress all optimizations.

NOTE: This does not occur with the Microsoft 32-bit compilers.

Additional reference words: kbinf 1.00 1.50 6.00 6.00a 6.00ax 7.00 8.00 8.00c KBCategory: kbtool KBSubcategory: CLIss Keywords : kb16bitonly

Last Reviewed: July 18, 1997