Bound checks for static readonly arrays #76578
Description
Noticed in @stephentoub's PR #76519 that for this case:
static readonly string[] s_singleDigitStringCache = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9" };
static string UInt32ToDecStr(uint value)
{
if (value < 10)
return s_singleDigitStringCache[value];
return null;
}we don't elide bound checks for statically inited field:
; Assembly listing for method Program:UInt32ToDecStr(uint):System.String
; Tier-1 compilation
G_M44444_IG01:
4883EC28 sub rsp, 40
G_M44444_IG02:
83F90A cmp ecx, 10
731E jae SHORT G_M44444_IG05
G_M44444_IG03:
48B8A01E80C89F010000 mov rax, 0x19FC8801EA0
488B00 mov rax, gword ptr [rax]
3B4808 cmp ecx, dword ptr [rax+08H]
7313 jae SHORT G_M44444_IG07
8BD1 mov edx, ecx
488B44D010 mov rax, gword ptr [rax+8*rdx+10H]
G_M44444_IG04:
4883C428 add rsp, 40
C3 ret
G_M44444_IG05:
33C0 xor rax, rax
G_M44444_IG06:
4883C428 add rsp, 40
C3 ret
G_M44444_IG07:
E8CD4B0D5F call CORINFO_HELP_RNGCHKFAIL
CC int3
; Total bytes of code 52I made a quick prototype EgorBo@70f911d - it works but it's blocked on API that is added in #76112 that is blocked on other things so I'm filing an issue to get back to it.
So, basically, we want to be able to fold str/array.Length to a constant for any static readonly field of Array or String type (doesn't matter if it's frozen or not)