https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70243
Bug ID: 70243 Summary: PowerPC V4DFmode should not use Altivec instructions on VSX systems Product: gcc Version: 6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: meissner at gcc dot gnu.org Target Milestone: --- The traditional Altivec single precision vector floating point instructions should not be used if the VSX instructions are available. This is due to the fact that the Altivec instruction does not use the current rounding mode, while the VSX instruction does. I did a quick glance through vsx.md and altivec.md, and I believe the only places we use the Altivec instruction by default is for 4 operand fused multiply-add and 4 operand fused negate multiply-subtract, when the destination operand does not overlap with the input operands.