https://bugs.llvm.org/show_bug.cgi?id=52216
Bug ID: 52216
Summary: [AArch64] improve codegen for -abs(x)
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: Backend: AArch64
Assignee: unassignedb...@nondot.org
Reporter: spatel+l...@rotateright.com
CC: arnaud.degrandmai...@arm.com,
llvm-bugs@lists.llvm.org, smithp...@googlemail.com,
ties.st...@arm.com
Splitting off from what was originally in bug 50991 (but that was fixed for x86
only):
define i32 @nabs32(i32 %0) {
%2 = tail call i32 @llvm.abs.i32(i32 %0, i1 true)
%3 = sub nsw i32 0, %2
ret i32 %3
}
define i64 @nabs64(i64 %0) {
%2 = tail call i64 @llvm.abs.i64(i64 %0, i1 true) #3
%3 = sub nsw i64 0, %2
ret i64 %3
}
declare i32 @llvm.abs.i32(i32, i1 immarg)
declare i64 @llvm.abs.i64(i64, i1 immarg)
----------------------------------------------------------------------------
% llc -o - nabs.ll -mtriple=aarch64
nabs32: // @nabs32
cmp w0, #0
cneg w8, w0, mi
neg w0, w8
ret
nabs64: // @nabs64
cmp x0, #0
cneg x8, x0, mi
neg x0, x8
ret
----------------------------------------------------------------------------
gcc does better on these:
https://godbolt.org/z/GbYha3Kso
...but note that i8 and possibly i16 are better as-is with clang.
--
You are receiving this mail because:
You are on the CC list for the bug._______________________________________________
llvm-bugs mailing list
llvm-bugs@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
