SPEC CPU2006 Flag Description for the Intel(R) C++ Compiler 9.1 for 32-bit applications and Intel(R) Fortran Compiler 9.1 for 32-bit applications

optimize for speed, but disable some optimizations which increase code size for a small speed benefit. Includes inline expansion except for intrinsic functions, global optimizations, string pooling optimizations. On IA-32 Windows platforms, -O1 sets the following:

/Qunroll0, /Oi-, /Op-, /Oy, /Gy, /Os, /GF (/Qvc7 and above), /Gf (/Qvc6 and below), /Ob2, and /Og

This is the default level of optimization. Optimizes for speed. The -O2 option includes O1 optimizations and in addition enables inlining of intrinsics and more speed optimizations. On IA-32 Windows platforms, -O2 sets the following:

/Og, /Oi-, /Os, /Oy, /Ob2, /GF (/Qvc7 and above), /Gf (/Qvc6 and below), /Gs, and /Gy.

Builds on -01 and -02 optimizations by enabling high-level optimization. This level does not guarantee higher performance unless loop and memory access transformation take place. In conjunction with -QaxK/-QxK and QaxW/QxW, this switch causes the compiler to perform more aggressive data dependency analysis than for -O2. This may result in longer compilation times. On IA-32 Windows platforms, -O3 sets the following:

/GF (/Qvc7 and above), /Gf (/Qvc6 and below), and /Ob2

enable single-file IP optimizations (within files, same as -Ob2)

Multi-file ip optimizations that includes:
- inline function expansion
- interprocedural constant propogation
- dead code elimination
- propagation of function characteristics
- passing arguments in registers
- loop-invariant code motion

The -fast option enhances execution speed across the entire program by including the following options that can improve run-time performance:

-O3   (maximum speed and high-level optimizations)

-Qipo (enables interprocedural optimizations across files)

-QxP  (generate code specialized for Intel Pentium 4 processor and compatible Intel processors with Streaming SIMD Extensions 3)

-Qprec-div- (disable -Qprec-div) where -Qprec-div improves precision of FP divides (some speed impact)

To override one of the options set by /fast, specify that option after the -fast option on the command line. The options set by /fast may change from release to release.

The -QxN and -QxP options target your program to run on Intel Pentium 4 and compatible Intel processors. The resulting code might contain unconditional use of features that are not supported on other processors. Programs, where the function main() is compiled with this option, will detect non compatible processors and generate an error message during execution. This option also enables new optimizations in addition to Intel processor specific optimizations.

These options also enable advanced data layout and code restructuring optimizations to improve memory accesses for Intel processors.

Allows the compiler to perform optimizations in FP divides that may impact precision while improving speed.

Instrument program for profiling for the first phase of two-phase profile guided otimization. This instrumentation gathers information about a program's execution paths and data values but does not gather information from hardware performance counters. The profile instrumentation also gathers data for optimizations which are unique to profile-feedback optimization.

Instructs the compiler to produce a profile-optimized executable and merges available dynamic information (.dyn) files into a pgopti.dpi file. If you perform multiple executions of the instrumented program, -Qprof_use merges the dynamic information files again and overwrites the previous pgopti.dpi file.
Without any other options, the current directory is searched for .dyn files

Enable C++ Exception Handling and RTTI
This option has the same effect as specifying /GX /GR.

This option enables C++ exception handling.

Enables C++ Run Time Type Information (RTTI).

Enable SmartHeap library usage by forcing the linker to ignore multiple definitions

Enable SmartHeap library usage by forcing the linker to ignore multiple definitions

MicroQuill SmartHeap Library 7.4 available from http://www.microquill.com/

set the stack reserve amount specified to the linker

Tells the compiler the maximum number of times to unroll loops.

Disables inline expansion of all intrinsic functions.

Disables conformance to the ANSI C and IEEE 754 standards for floating-point arithmetic.

Allows use of EBP as a general-purpose register in optimizations.

This option enables most speed optimizations, but disables some that increase code size for a small speed benefit.

This option enables global optimizations.

Specifies the level of inline function expansion.

Ob0 - Disables inlining of user-defined functions. Note that statement functions are always inlined.

Ob1 - Enables inlining when an inline keyword or an inline attribute is specified. Also enables inlining according to the C++ language.

Ob2 - Enables inlining of any function at the compiler's discretion.

This option tells the compiler to separate functions into COMDATs for the linker.

This option enables read only string-pooling optimization.

This option enables read/write string-pooling optimization.

This option disables stack-checking for routines with 4096 bytes of local variables and compiler temporaries.

For mixed-language benchmarks, tell the compiler to convert routine names to lowercase for compatibility

For mixed-language benchmarks, tell the compiler to assume that routine name end with an underscore

Tell the compiler to treat source files as C++

Invoke the Intel C/C++ compiler for 32 bit applications in MS VC .Net 2003 compatibility mode

Invoke the Intel Fortran compiler for 32 bit applications

Invoke the Intel C compiler in C99 mode

Invoke the Intel C and C++ compilers in .Net 2003 compatibility mode