HITACHI Flags Description.
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enable -xP -O3 -ipo -no-prec-div -static
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, -prof_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 the auto-parallelizer to generate multi-threaded code for loops that can be safely executed in parallel
Enable -O2 plus more aggressive optimizations that may not improve performance for all programs. On Linux platforms, -O3 sets the -fp flag.
Enable optimizations of defaults level. -O2 includes -O1 optimizations and in addition enables inlining of intrinsics and more speed optimizations.
Optimize for maximum 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 Linux platforms, -O1 sets the following:
-unroll0 -fno-builtin -mno-ieee-fp -fomit-frame-pointer -ffunction-sections
Set maximum number of times to unroll loops. Use n=0 to disable loop unroller.
disable inline expansion of intrinsic functions
Enables improved floating-point consistency. Floating-point operations are not reordered and the result of each floating-point operation is stored in the target variable rather than being kept in the floating- point processor for use in a subsequent calculation. This is the same as specifying -fltconsistency or -mp.
The default, -mno-ieee-fp, provides better accuracy and run-time per- formance at the expense of less consistent floating-point results.
enable using EBP as general purpose register
separate functions for the linker (COMDAT)
disable using EBP as general purpose register
generate specialized code to run exclusively on processors indicated by Intel Core(TM) Duo processors, Intel Core(TM) Solo processors, Intel Pentium 4 and compatible Intel processors with Streaming SIMD Extensions 3 (SSE3) instruction support
enable multi-file Interprocedural Optimizations (between files)
improve speed of floating-point divides and disable improved precision of floating-point divides
prevents linking with shared libraries
do not link against Fortran main object Used when linking Fortran objects with C main program