- Infos im HLRS Wiki sind nicht rechtsverbindlich und ohne Gewähr -
- Information contained in the HLRS Wiki is not legally binding and HLRS is not responsible for any damages that might result from its use -
Useful Compiler Options On x86: Difference between revisions
From HLRS Platforms
Jump to navigationJump to search
(Added cray asm options) |
(added cray code type options) |
||
| Line 53: | Line 53: | ||
! ICC Option | ! ICC Option | ||
! PGCC Option | ! PGCC Option | ||
! CrayCC Option | |||
|- | |- | ||
| compile C code as C99 | | compile C code as C99 | ||
| Line 58: | Line 59: | ||
| -std=c99 | | -std=c99 | ||
| -c99 | | -c99 | ||
| on by default | |||
|- | |- | ||
| enable OpenMP | | enable OpenMP | ||
| -fopenmp | | -fopenmp | ||
| -openmp | | -openmp | ||
| -mp | |||
| on by default | | on by default | ||
|- | |- | ||
| Line 68: | Line 71: | ||
| not supported | | not supported | ||
| -ta=host -ta=nvidia or -ta=cc13 | | -ta=host -ta=nvidia or -ta=cc13 | ||
| not supported | |||
|} | |} | ||
Revision as of 15:34, 16 February 2011
Introduction
The following options are helpful to improve performance and debug performance problems when compiling code on x86 processors using GCC, the Intel or PGI C or Fortran compilers.
Optimization Switches
| Description | GCC Option | ICC Option | PGCC Option |
|---|---|---|---|
| Enable aggressive optimization features in general | -O3 | -fast | -fast |
| Enable relaxed floating pointing builtin functions | -ffast-math | -fp-model fast | -Mfprelaxed |
| Round demormalized FP values to zero | included in -ffast-math | -ftz | -Mdaz |
| Assume associativity of floating point operations | -fno-signed-zeros -fno-trapping-math -fassociative-math | –Mvect=assoc | |
| Assume C ansi aliasing rules are not violated | -fstrict-aliasing (included in -O2 and -O3) | -ansi-alias | |
| Enable interprocedural optimization over file boundaries | -fwhole-program | -ipo (included -fast) | -Mipa=fast or -Mipa=fast,inline |
Notes
- using -ansi-alias often helps the auto-vectorize code with the intel compiler, especially when OpenMP is enabled
Input Language
| Description | GCC Option | ICC Option | PGCC Option | CrayCC Option |
|---|---|---|---|---|
| compile C code as C99 | -std=c99 or -std=gnu99 | -std=c99 | -c99 | on by default |
| enable OpenMP | -fopenmp | -openmp | -mp | on by default |
| enable accelerator directives | not supported | not supported | -ta=host -ta=nvidia or -ta=cc13 | not supported |
Target Architecture
| Description | GCC Option | ICC Option | PGCC Option |
|---|---|---|---|
| select target processor | -march=<processor name> | -x <processor name> | -tp <processor name> |
| enable automatic SMP parallelization | not supported | not supported | -Mconcur |
Notes
- the list of recognized processors is different for each compiler, very long and continuously getting longer. See the manuals of the compilers for those lists.
Diagnostic Output
| Description | GCC Option | ICC Option | PGCC Option |
|---|---|---|---|
| generate auto-vectorization information | -ftree-vectorizer-verbose=<level> | -vec-report=<level> | -Minfo=vec |
Notes
- the PGI compiler has several other -Minfo=<type> switches to produce diagnostic output on inlining, unrolling, IPO, auto-parallelization and accelerator usage
Assembler Output
| Description | GCC Option | ICC Option | PGCC Option | CrayCC Option |
|---|---|---|---|---|
| generate assembler output instead of object file | -S | -S | -S | -S |
| generate assembler output with source code included in asm file | -g -Wa,-a,-ad | -S -fsource-asm | -S -Manno | -h list=d
(not asm but intermediate representation) |