https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84100
Bug ID: 84100 Summary: Function __attribute__((optimize(align-loops=32))) gives spurious warning Product: gcc Version: 7.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: gcc at gmch dot uk Target Milestone: --- With v7.2.1, compiling for recent x86_64, the command line option "-falign-loops=32" is accepted and has the desired effect. However I find that both: _Pragma("GCC optimize(\"align-loops=32\")") and: __attribute__((optimize("align-loops=32"))) are rejected with a "warning: bad option '-falign-loops=32'" -- reported for each and every affected function. I have tried optimize("align-loops=x") for x=0, 1, 8 and 16 -- all are rejected the same way. FWIW, brief checks with Compiler Explorer suggest: 1) this appears to be a new bug in v7, or at least since v6.3. 2) v6.3 accepts the _Pragma(), but does *not* do the requested alignment. 3) v5.4 accepts the _Pragma(), and does the requested alignment. Chris