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* [Bug tree-optimization/103803] New: i++; i = i % constant -> i >= constant-1 ? 0 : i+1
@ 2021-12-22 9:27 pinskia at gcc dot gnu.org
0 siblings, 0 replies; only message in thread
From: pinskia at gcc dot gnu.org @ 2021-12-22 9:27 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103803
Bug ID: 103803
Summary: i++; i = i % constant -> i >= constant-1 ? 0 : i+1
Product: gcc
Version: 12.0
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 next_trivial(int i) {
if (i < 0 || i >= 10) __builtin_unreachable ();
++i;
i = i % 10;
return i;
}
int next_trivial1(int i) {
if (i < 0 || i >= 10) __builtin_unreachable ();
++i;
if (i >= 10) i = 0;
return i;
}
These two should produce the same assembly code, the next_trivial1 is better
than next_trivial
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2021-12-22 9:27 [Bug tree-optimization/103803] New: i++; i = i % constant -> i >= constant-1 ? 0 : i+1 pinskia at gcc dot gnu.org
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