https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61757
--- Comment #29 from Pat Haugen <pthaugen at gcc dot gnu.org> --- (In reply to Segher Boessenkool from comment #21) > (In reply to Pat Haugen from comment #19) > > So in the case where MIN_INT32 is passed (sign extended), the upper 32 bits > > are '1' so r212352 returns a value of 63 whereas prior revisions returned a > > value of 31. > > When called with r3=ffffffff80000000 the new code > returns -1 as far as I can see? The new code is doing a logical shift right of the full 64-bit reg, which will require 63 shifts for the value in the reg to become zero. > And it should be called with 0000000080000000 instead; > does the caller not have a prototype in scope? No, there is no prototype, which is really the problem because it should be passed zero-extended as you say in which case either of the code sequences would work. I tried the benchmark after the patch went in, and it is back to generating the rldicl insn and the benchmark passes.
