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* [Bug tree-optimization/111221] New: Floating point handling a*1.0 vs. a+0.0 @ 2023-08-29 5:54 tkoenig at gcc dot gnu.org 2023-08-29 6:00 ` [Bug tree-optimization/111221] " pinskia at gcc dot gnu.org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: tkoenig at gcc dot gnu.org @ 2023-08-29 5:54 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111221 Bug ID: 111221 Summary: Floating point handling a*1.0 vs. a+0.0 Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: tkoenig at gcc dot gnu.org Target Milestone: --- I just noticed that gcc will optimize away multiplying a floating point number with 1.0, but will not do for an addition with 0.0. Example, with -O3, double add0 (double a) { return a + 0.0; } double mul1 (double a) { return a * 1.0; } yields add0: .LFB0: .cfi_startproc pxor %xmm1, %xmm1 addsd %xmm1, %xmm0 ret vs. mul1: .LFB1: .cfi_startproc ret which seems inconsistent. If this is the result of a deliberate design decision, feel free to close as WONTFIX. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/111221] Floating point handling a*1.0 vs. a+0.0 2023-08-29 5:54 [Bug tree-optimization/111221] New: Floating point handling a*1.0 vs. a+0.0 tkoenig at gcc dot gnu.org @ 2023-08-29 6:00 ` pinskia at gcc dot gnu.org 2023-08-29 6:01 ` pinskia at gcc dot gnu.org 2023-08-29 9:56 ` xry111 at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-08-29 6:00 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111221 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- -0.0 * 1.0 is still -0.0 While -0.0 + 0.0 is 0.0 rather than -0.0. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/111221] Floating point handling a*1.0 vs. a+0.0 2023-08-29 5:54 [Bug tree-optimization/111221] New: Floating point handling a*1.0 vs. a+0.0 tkoenig at gcc dot gnu.org 2023-08-29 6:00 ` [Bug tree-optimization/111221] " pinskia at gcc dot gnu.org @ 2023-08-29 6:01 ` pinskia at gcc dot gnu.org 2023-08-29 9:56 ` xry111 at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-08-29 6:01 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111221 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- That is GCC will remove additions of -0.0: double addneg0 (double a) { return a + -0.0; } Gets optimized to just `return a;`. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/111221] Floating point handling a*1.0 vs. a+0.0 2023-08-29 5:54 [Bug tree-optimization/111221] New: Floating point handling a*1.0 vs. a+0.0 tkoenig at gcc dot gnu.org 2023-08-29 6:00 ` [Bug tree-optimization/111221] " pinskia at gcc dot gnu.org 2023-08-29 6:01 ` pinskia at gcc dot gnu.org @ 2023-08-29 9:56 ` xry111 at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: xry111 at gcc dot gnu.org @ 2023-08-29 9:56 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111221 Xi Ruoyao <xry111 at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |xry111 at gcc dot gnu.org --- Comment #3 from Xi Ruoyao <xry111 at gcc dot gnu.org> --- FWIW if you want "add0" to be optimized use -fno-signed-zeros. ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-08-29 9:56 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2023-08-29 5:54 [Bug tree-optimization/111221] New: Floating point handling a*1.0 vs. a+0.0 tkoenig at gcc dot gnu.org 2023-08-29 6:00 ` [Bug tree-optimization/111221] " pinskia at gcc dot gnu.org 2023-08-29 6:01 ` pinskia at gcc dot gnu.org 2023-08-29 9:56 ` xry111 at gcc dot gnu.org
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