This PR is meant to be a central place to record information about this issue.
The default ABI for 32-bit PowerPC GNU/Linux does not pass vectors in AltiVec registers and does not save and restore AltiVec registers in functions that use those registers. With -mabi=altivec, vectors are passed in AltiVec registers and AltiVec registers used within a function are saved and restored. This has always been a problem if multiple functions in a call chain use AltiVec registers without the AltiVec ABI, but it's become a more visible issue with -ftree-vectorize included in -O3, particularly when the user specifies a CPU that supports AltiVec and might not realize that those two options imply that AltiVec registers will likely be used in multiple functions in a call stack without saving and restoring them. Two recent PRs that are due to this problem are 34038 and 34437. A somewhat-rel ated PR is 33899. There were some recent discussions of this issue: http://gcc.gnu.org/ml/gcc-patches/2007-07/msg02159.html http://gcc.gnu.org/ml/gcc-patches/2007-08/msg00438.html This ought to be fixed either by using the AltiVec ABI by default or by changing the non-AltiVec ABI to save and restore AltiVec registers in functions that use them. -- Summary: no-altivec ABI should be fixed or no longer be the default Product: gcc Version: 4.3.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: janis at gcc dot gnu dot org GCC target triplet: powerpc-linux http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34526
