Download PathScale™ Compiler Suite User Guide

4 – The PathScale C/C++ Compiler
Using the C/C++ Compilers
The command-line flags for both compilers are compatible with those taken by the
GCC suite. See section 4.1 for more discussion of this.
4.1
Using the C/C++ Compilers
If you currently use the GCC compilers, the PathScale compiler commands will be
familiar. Makefiles that presently work with GCC should operate with the PathScale
compilers effortlessly–simply change the command used to invoke the compiler and
rebuild. See section 5.7.1 for information on modifying existing scripts
The invocation of the compiler is identical to the GCC compilers, but the flags to
control the compilation are different. We have sought to provide flags compatible
with GCC’s flag usage whenever possible and also provide optimization features
that are absent in GCC, such as IPA and LNO.
Generally speaking, instead of being a single component as in GCC, the PathScale
compiler is structured into components that perform different classes of
optimizations. Accordingly, compilation flags are provided under group names like
-IPA, -LNO, -OPT, -CG, etc. For this reason, many of the compilation flags in our
compiler will differ from those in GCC. See the eko man page for more information.
The default optimization level is 2. This is equivalent to passing -O2 as a flag. The
following three commands are identical in their function:
$ pathcc hello.c
$ pathcc -O hello.c
$ pathcc -O2 hello.c
See section 7.1 for information about the optimization levels available for use with
the compiler.
To run with -Ofast or with -ipa, the flag must also be given on the link command.
$ pathCC -c -Ofast warpengine.cc
$ pathCC -c -Ofast wormhole.cc
$ pathCC -o ftl -Ofast warpengine.o wormhole.o
See section 7.3 for information on -ipa and -Ofast.
4.1.1
Accessing the GCC 4.x Front-ends for C and C++
This release is compatible with version 4.2.0 of the GNU C/C++ compiler in terms
of the source language constructs they support. This is the default on Linux
distributions whose compiler is GNU 4.x. On systems with GNU 3.x compilers,
pathcc/pathCC will generate code compitable with GNU 3.x. You can use the "-gnu4"
option to direct pathcc/pathCC to be compitable with GNU 4.x. A sample command
for C is:
$ pathcc -gnu4 world.c
4-2