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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/94543] missed optimization with MIN and AND with type promotion Date: Tue, 14 Apr 2020 06:44:31 +0000 [thread overview] Message-ID: <bug-94543-4-TYZvQovnYe@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-94543-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94543 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Version|tree-ssa |10.0 Last reconfirmed| |2020-04-14 Status|UNCONFIRMED |NEW Target| |x86_64-*-* i?86-*-* Keywords| |missed-optimization Component|middle-end |rtl-optimization --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- The issue is that we fail to have a proper representation of the target on the GIMPLE level. We expand to RTL from the optimal <bb 2> [local count: 1073741824]: # RANGE [0, 255] NONZERO 255 _1 = MIN_EXPR <x_2(D), 255>; # RANGE [0, 255] NONZERO 255 _3 = (unsigned int) _1; return _3; but that produces (insn 10 6 9 (set (reg:HI 88) (const_int 255 [0xff])) "x.c":1:56 -1 (nil)) (insn 9 10 11 (set (reg:CC 17 flags) (compare:CC (reg/v:HI 84 [ x ]) (const_int 255 [0xff]))) "x.c":1:56 -1 (nil)) (insn 11 9 12 (set (reg:HI 87) (if_then_else:HI (leu (reg:CC 17 flags) (const_int 0 [0])) (reg/v:HI 84 [ x ]) (reg:HI 88))) "x.c":1:56 -1 (nil)) (insn 12 11 13 (set (reg:SI 86) (zero_extend:SI (reg:HI 87))) "x.c":1:61 -1 (nil)) given fort the (unsigned int) _1 zero-extension we don't have any other representation on GIMPLE to elide the zero-extension. I'm also not sure if (subreg:SI (reg:HI 87)) would be correct in all cases. Marking rtl-optimization but eventually it's also a target issue. We also don't have anything like a reg-note to tell ranges of a set? Anyway, even on RTL the range of reg:HI 87 is clearly visible.
prev parent reply other threads:[~2020-04-14 6:44 UTC|newest] Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-04-09 19:13 [Bug middle-end/94543] New: " rth at gcc dot gnu.org 2020-04-14 6:44 ` rguenth at gcc dot gnu.org [this message]
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