https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92758
Bug ID: 92758 Summary: [10 regression] r278833 breaks gcc.target/powerpc/fold-vec-splat-floatdouble.c Product: gcc Version: 10.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: seurer at gcc dot gnu.org Target Milestone: --- FAIL: gcc.target/powerpc/fold-vec-splat-floatdouble.c scan-assembler-times xxpermdi 3 This is one of those tests that just counts assembler instructions and the count of xxpermdi changed seurer@makalu-lp1:~/gcc/build/gcc-test2$ diff fold-vec-splat-floatdouble.s.r278832 fold-vec-splat-floatdouble.s.r278833 94c94,95 < xxpermdi 34,34,34,0 --- > xxlor 0,34,34 > xxpermdi 34,0,0,0 113c114,115 < xxpermdi 34,34,34,3 --- > xxpermdi 0,34,34,2 > xxpermdi 34,0,0,0 which in this case looks like missed optimization given the extra instructions are just copying things needlessly between registers.