https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113576
--- Comment #6 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
Another potential buggy place is
240 vexit_reduc_67 = mask_patt_43.28_62 & mask_patt_43.28_63;
241 if (vexit_reduc_67 == { -1, -1, -1, -1 })
242 goto <bb 6>; [94.50%]
243 else
is expanded to
319(insn 69 68 70 8 (set (reg:CCZ 17 flags)
320 (compare:CCZ (reg:QI 189 [ vexit_reduc_67 ])
321 (const_int -1 [0xffffffffffffffff]))) "test.c":83:18 discrim 1
9 {*cmpqi_1}
But it should only test the lower 4 bits, the higher part is zeroed by avx512
comparison instructions.
293(insn 65 64 66 8 (set (reg:QI 186 [ mask_patt_43.28_62 ])
294 (unspec:QI [
295 (reg:V4DI 124 [ vect__29.26 ])
296 (reg:V4DI 185)
297 (const_int 0 [0])
298 ] UNSPEC_PCMP)) "test.c":83:18 discrim 1 2811
{avx512vl_cmpv4di3}
299 (nil))
300(insn 66 65 67 8 (set (reg:V4DI 187)
301 (const_vector:V4DI [
302 (const_int 0 [0]) repeated x4
303 ])) "test.c":83:18 discrim 1 2021 {movv4di_internal}
304 (nil))
305(insn 67 66 68 8 (set (reg:QI 188 [ mask_patt_43.28_63 ])
306 (unspec:QI [
307 (reg:V4DI 125 [ vect__29.27 ])
308 (reg:V4DI 187)
309 (const_int 0 [0])
310 ] UNSPEC_PCMP)) "test.c":83:18 discrim 1 2811
{avx512vl_cmpv4di3}
311 (nil))
312(insn 68 67 69 8 (parallel [
313 (set (reg:QI 189 [ vexit_reduc_67 ])
314 (and:QI (reg:QI 186 [ mask_patt_43.28_62 ])
315 (reg:QI 188 [ mask_patt_43.28_63 ])))
316 (clobber (reg:CC 17 flags))
317 ]) "test.c":83:18 discrim 1 618 {*andqi_1}
318 (nil))
