These configuration switches will allow the PowerPC GCC developers to switch defaults in the compiler to debug the code, before making the decision to flip the default permanently. In the future, when the defaults have been changed, these configuration options would allow developers to go back to the previous versions without modifying the code using the --disable-<switch> form.
The first option is --enable-lra, which changes the compiler so that the default is to use the LRA register allocator instead of the older RELOAD allocator. The PowerPC team would like to switch the default, but there is a critical bug in LRA that must be fixed before we can change the default: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69847 The second option is --enable-float128, which changes the compiler so that the default for VSX systems is to enable the __float128 keyword to allow users access to the IEEE 128-bit floating point implementation without having to use the keyword. Both of these switches are debug switches, and are not meant to be used by non-developers. The --enable-lra swich causes the following tests to fail: * testsuite/gcc.target/powerpc/bool3-p7.c * testsuite/gcc.target/powerpc/bool3-p8.c See bug 71846 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71846) for more details. The --enable-float128 switch causes libquadmath and libstdc++ to fail because we do not yet have enough of the support in the compiler to allow these libraries to build. It is our intention, that we will use the --enable-float128 option and work on getting the libraries fixed. If I build just a C compiler and disable building libquadmath, there are no regressions in the C tests with __float128 enabled or disabled. Can I check these options into the trunk as non-default options? -- Michael Meissner, IBM IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA email: meiss...@linux.vnet.ibm.com, phone: +1 (978) 899-4797
