https://bugs.llvm.org/show_bug.cgi?id=41363
Bug ID: 41363
Summary: ARM backend doesn't realize when behavior of left
shift of 32 can be used to eliminate branches
Product: new-bugs
Version: 8.0
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: new bugs
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected], [email protected]
As documented here, ARM's right shift returns 0 when the shift is greater than
32.
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0552a/BABJCCDH.html
But llvm doesn't eliminate this branch https://zig.godbolt.org/z/FPt9Nm
export fn shiftrarm(int: u32, shift: u8) u32 {
if (shift == 0) {
return 0;
} else {
return (int >> @truncate(u5, (32 - shift)));
}
}
I couldn't find documentation for other widths of shifts.
--
You are receiving this mail because:
You are on the CC list for the bug._______________________________________________
llvm-bugs mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
