Loops aren't cloned for Spans #82946
Description
void Test(Span<byte> source)
{
for (int i = 0; i < 100; i++)
source[i] = 0;
}Codegen:
; Method Progr:Test(System.Span`1[ubyte]):this
G_M11420_IG01:
4883EC28 sub rsp, 40
G_M11420_IG02:
33C0 xor eax, eax
align [0 bytes for IG03]
G_M11420_IG03:
3B4208 cmp eax, dword ptr [rdx+08H]
7317 jae SHORT G_M11420_IG05
488B0A mov rcx, bword ptr [rdx]
448BC0 mov r8d, eax
42C6040100 mov byte ptr [rcx+r8], 0
FFC0 inc eax
83F864 cmp eax, 100
7CE9 jl SHORT G_M11420_IG03
G_M11420_IG04:
4883C428 add rsp, 40
C3 ret
G_M11420_IG05:
E829C64C5F call CORINFO_HELP_RNGCHKFAIL
CC int3
; Total bytes of code: 40*************** Starting PHASE Clone loops
*************** In optCloneLoops()
Considering loop L00 to clone for optimizations.
Not checking loop L00 -- no array bounds or type tests in this method
------------------------------------------------------------
No clonable loops
*************** Finishing PHASE Clone loops
Here it is expected to have two loops and one of them without bound checks.
cc @BruceForstall @dotnet/jit-contrib
category:cq
theme:loop-opt
skill-level:expert
cost:medium
impact:large