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* [Bug tree-optimization/95408] New: Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand @ 2020-05-29 9:40 gabravier at gmail dot com 2021-04-26 1:15 ` [Bug tree-optimization/95408] " pinskia at gcc dot gnu.org ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: gabravier at gmail dot com @ 2020-05-29 9:40 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95408 Bug ID: 95408 Summary: Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand Product: gcc Version: 11.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: gabravier at gmail dot com Target Milestone: --- bool f(int x) { return x & -((unsigned)x < some_constant); } This can be optimized to `return (unsigned)(x - 1) < (some_constant - 1);`. This transformation is done by LLVM, but not by GCC. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/95408] Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand 2020-05-29 9:40 [Bug tree-optimization/95408] New: Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand gabravier at gmail dot com @ 2021-04-26 1:15 ` pinskia at gcc dot gnu.org 2023-05-13 5:47 ` pinskia at gcc dot gnu.org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-04-26 1:15 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95408 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|normal |enhancement ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/95408] Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand 2020-05-29 9:40 [Bug tree-optimization/95408] New: Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand gabravier at gmail dot com 2021-04-26 1:15 ` [Bug tree-optimization/95408] " pinskia at gcc dot gnu.org @ 2023-05-13 5:47 ` pinskia at gcc dot gnu.org 2023-08-23 2:36 ` pinskia at gcc dot gnu.org 2023-09-16 6:25 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-05-13 5:47 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95408 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Assignee|unassigned at gcc dot gnu.org |pinskia at gcc dot gnu.org Last reconfirmed| |2023-05-13 Status|UNCONFIRMED |ASSIGNED --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- For unsigned x (to simplify things first). In forwardprop4 we have _1 = x_4(D) <= 121211; _3 = _1 ? x_4(D) : 0; _5 = _3 != 0; This could be done as: x_4(D) <= 121211 ? x_4(D) != 0 : 0 Which then would be: (x_4(D) <= 121211 & x_4(D) != 0) ((x_4(D) - 1) <= 121210) So I have a patch which does the second step into the 3rd expression (there is another bug or 2 about it). the 3rd expression into the final is already done. It is just the first that needs to happen to written up. Something like this for the first step. (for op (tcc_comparison) /* (c ? a : CST0) op CST1 --> c ? (a op CST1) : (CST0 op CST1) */ (simplify (op (cond:s @0 @1 CONSTANT_CLASS_P@2) CONSTANT_CLASS_P@3) (cond! @0 (op @1 @3) (op @2 @4))) So mine. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/95408] Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand 2020-05-29 9:40 [Bug tree-optimization/95408] New: Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand gabravier at gmail dot com 2021-04-26 1:15 ` [Bug tree-optimization/95408] " pinskia at gcc dot gnu.org 2023-05-13 5:47 ` pinskia at gcc dot gnu.org @ 2023-08-23 2:36 ` pinskia at gcc dot gnu.org 2023-09-16 6:25 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-08-23 2:36 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95408 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- In forwprop1 we have: _2 = x.0_1 <= 121210; _3 = (int) _2; _4 = _3 * x_5(D); _6 = _4 != 0; since _3 is zero_one_valued we could do instead: ``` (for cmp (ne eq ) bitop (bit_and bit_ior) (simplify (cmp (mult zero_one_valued_p@0 @1) integer_zerop@2) (bitop! (convert @0) (ne @1 @2)))) ``` And we should be able to get it earlier on. Still mine and I will look into the above. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/95408] Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand 2020-05-29 9:40 [Bug tree-optimization/95408] New: Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand gabravier at gmail dot com ` (2 preceding siblings ...) 2023-08-23 2:36 ` pinskia at gcc dot gnu.org @ 2023-09-16 6:25 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-09-16 6:25 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95408 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- URL| |https://gcc.gnu.org/piperma | |il/gcc-patches/2023-Septemb | |er/630651.html Keywords| |patch --- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- I was looking for this one when I wrote https://gcc.gnu.org/pipermail/gcc-patches/2023-September/630651.html . ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2023-09-16 6:25 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-05-29 9:40 [Bug tree-optimization/95408] New: Failure to optimize bitwise and with negated conditional using the same operand to conditional with decremented operand gabravier at gmail dot com 2021-04-26 1:15 ` [Bug tree-optimization/95408] " pinskia at gcc dot gnu.org 2023-05-13 5:47 ` pinskia at gcc dot gnu.org 2023-08-23 2:36 ` pinskia at gcc dot gnu.org 2023-09-16 6:25 ` pinskia at gcc dot gnu.org
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