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* [Bug tree-optimization/114894] New: `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` @ 2024-04-30 6:18 pinskia at gcc dot gnu.org 2024-04-30 6:18 ` [Bug tree-optimization/114894] " pinskia at gcc dot gnu.org ` (5 more replies) 0 siblings, 6 replies; 7+ messages in thread From: pinskia at gcc dot gnu.org @ 2024-04-30 6:18 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114894 Bug ID: 114894 Summary: `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` Product: gcc Version: 14.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: enhancement Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: pinskia at gcc dot gnu.org Target Milestone: --- Take: ``` int fmul(int a, int b) { int c = a * b; int d = a != 0; return c & -d; } int fand(int a, int b) { int c = a & b; int d = a != 0; return c & -d; } ``` These should just optimize to: `return a * b;` and `return a & b;`. Currently we get: ``` c_4 = a_2(D) * b_3(D); _1 = a_2(D) != 0; _6 = _1 ? c_4 : 0; ... c_4 = a_2(D) & b_3(D); _1 = a_2(D) != 0; _6 = _1 ? c_4 : 0; ``` For: ``` int fmul1(int a, int b) { int c = a * b; if (a != 0) return c; return 0; } int fand1(int a, int b) { int c = a & b; if (a != 0) return c; return 0; } ``` It is not until phiopt4 we are able to remove the conditional. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/114894] `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` 2024-04-30 6:18 [Bug tree-optimization/114894] New: `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` pinskia at gcc dot gnu.org @ 2024-04-30 6:18 ` pinskia at gcc dot gnu.org 2024-04-30 6:23 ` pinskia at gcc dot gnu.org ` (4 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: pinskia at gcc dot gnu.org @ 2024-04-30 6:18 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114894 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed| |2024-04-30 Ever confirmed|0 |1 Status|UNCONFIRMED |ASSIGNED Assignee|unassigned at gcc dot gnu.org |pinskia at gcc dot gnu.org --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Mine. Found while moving value_replacement over to use match-and-simplify. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/114894] `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` 2024-04-30 6:18 [Bug tree-optimization/114894] New: `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` pinskia at gcc dot gnu.org 2024-04-30 6:18 ` [Bug tree-optimization/114894] " pinskia at gcc dot gnu.org @ 2024-04-30 6:23 ` pinskia at gcc dot gnu.org 2024-04-30 18:04 ` pinskia at gcc dot gnu.org ` (3 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: pinskia at gcc dot gnu.org @ 2024-04-30 6:23 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114894 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- See Also| |https://gcc.gnu.org/bugzill | |a/show_bug.cgi?id=59100 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- gcc.dg/tree-ssa/phi-opt-12.c is the testcase . ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/114894] `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` 2024-04-30 6:18 [Bug tree-optimization/114894] New: `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` pinskia at gcc dot gnu.org 2024-04-30 6:18 ` [Bug tree-optimization/114894] " pinskia at gcc dot gnu.org 2024-04-30 6:23 ` pinskia at gcc dot gnu.org @ 2024-04-30 18:04 ` pinskia at gcc dot gnu.org 2024-04-30 18:18 ` pinskia at gcc dot gnu.org ` (2 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: pinskia at gcc dot gnu.org @ 2024-04-30 18:04 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114894 --- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Note we should catch this too: ``` int fmul2(unsigned a, int b) { int c = a * b; int d = a != 0; return c & -d; } ``` Which is more complex ... ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/114894] `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` 2024-04-30 6:18 [Bug tree-optimization/114894] New: `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` pinskia at gcc dot gnu.org ` (2 preceding siblings ...) 2024-04-30 18:04 ` pinskia at gcc dot gnu.org @ 2024-04-30 18:18 ` pinskia at gcc dot gnu.org 2024-05-07 21:42 ` cvs-commit at gcc dot gnu.org 2024-05-07 21:43 ` pinskia at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: pinskia at gcc dot gnu.org @ 2024-04-30 18:18 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114894 --- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> --- And divides should happen if we know if the divisor is non-zero: eg: ``` int fdiv(int a, int b) { if (b == 0) __builtin_unreachable(); int c = a / b; int d = a != 0; return c & -d; } ``` Phi-OPT value-replacement does handle it for ifs right now: ``` int fmul3(int a, int b) { if (b == 0) __builtin_unreachable(); int c = a / b; if (a == 0) return 0; return c; int d = a != 0; return c & -d; } ``` ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/114894] `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` 2024-04-30 6:18 [Bug tree-optimization/114894] New: `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` pinskia at gcc dot gnu.org ` (3 preceding siblings ...) 2024-04-30 18:18 ` pinskia at gcc dot gnu.org @ 2024-05-07 21:42 ` cvs-commit at gcc dot gnu.org 2024-05-07 21:43 ` pinskia at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: cvs-commit at gcc dot gnu.org @ 2024-05-07 21:42 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114894 --- Comment #5 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Andrew Pinski <pinskia@gcc.gnu.org>: https://gcc.gnu.org/g:e472527c7b45d23e8dfd0fb767a6e663b4bc136e commit r15-307-ge472527c7b45d23e8dfd0fb767a6e663b4bc136e Author: Andrew Pinski <quic_apinski@quicinc.com> Date: Tue Apr 30 14:45:26 2024 -0700 MATCH: Add some more value_replacement simplifications (a != 0 ? expr : 0) to match This adds a few more of what is currently done in phiopt's value_replacement to match. I noticed this when I was hooking up phiopt's value_replacement code to use match and disabling the old code. But this can be done independently from the hooking up phiopt's value_replacement as phiopt is already hooked up for simplified versions already. /* a != 0 ? a / b : 0 -> a / b iff b is nonzero. */ /* a != 0 ? a * b : 0 -> a * b */ /* a != 0 ? a & b : 0 -> a & b */ We prefer the `cond ? a : 0` forms to allow optimization of `a * cond` which uses that form. Bootstrapped and tested on x86_64-linux-gnu with no regressions. PR tree-optimization/114894 gcc/ChangeLog: * match.pd (`a != 0 ? a / b : 0`): New pattern. (`a != 0 ? a * b : 0`): New pattern. (`a != 0 ? a & b : 0`): New pattern. gcc/testsuite/ChangeLog: * gcc.dg/tree-ssa/phi-opt-value-5.c: New test. Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com> ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/114894] `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` 2024-04-30 6:18 [Bug tree-optimization/114894] New: `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` pinskia at gcc dot gnu.org ` (4 preceding siblings ...) 2024-05-07 21:42 ` cvs-commit at gcc dot gnu.org @ 2024-05-07 21:43 ` pinskia at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: pinskia at gcc dot gnu.org @ 2024-05-07 21:43 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114894 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|ASSIGNED |RESOLVED Target Milestone|--- |15.0 Resolution|--- |FIXED --- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Fixed. ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2024-05-07 21:43 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2024-04-30 6:18 [Bug tree-optimization/114894] New: `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b` pinskia at gcc dot gnu.org 2024-04-30 6:18 ` [Bug tree-optimization/114894] " pinskia at gcc dot gnu.org 2024-04-30 6:23 ` pinskia at gcc dot gnu.org 2024-04-30 18:04 ` pinskia at gcc dot gnu.org 2024-04-30 18:18 ` pinskia at gcc dot gnu.org 2024-05-07 21:42 ` cvs-commit at gcc dot gnu.org 2024-05-07 21:43 ` pinskia at gcc dot gnu.org
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