Insert int3 after non-returning calls at the end of basic blocks.

[erozenfeld]

This is a follow-up to #17501 that fixed #17398.

#17398 was caused by a break in implicit contract between codegen and
gc pointer reporting in fully-interruptible mode: the latter assumed that
register gc pointer liveness doesn't change across calls while #6103 introduced
codegen where it wasn't true.

#17501 changed gc pointer reporting not to expect that register gc pointer liveness
doesn't change across calls.

This change inserts int3 after non-returning calls at the end of basic blocks
so that gc pointer liveness doesn't change across calls. This is additional
insurance in case any other place in runtime is dependent on that contract.

[erozenfeld]

jit-diff --frameworks:

Summary:
(Note: Lower is better)
Total bytes of diff: 4444 (0.02% of base)
    diff is a regression.
Total byte diff includes 0 bytes from reconciling methods
        Base had    0 unique methods,        0 unique bytes
        Diff had    0 unique methods,        0 unique bytes
Top file regressions by size (bytes):
        3817 : System.Private.CoreLib.dasm (0.13% of base)
         436 : System.Collections.Immutable.dasm (0.15% of base)
          74 : System.Private.DataContractSerialization.dasm (0.01% of base)
          26 : System.Memory.dasm (0.04% of base)
          26 : System.Net.Http.dasm (0.01% of base)
18 total files with size differences (0 improved, 18 regressed), 112 unchanged.
Top method regessions by size (bytes):
         174 : System.Private.CoreLib.dasm - Dictionary`2:System.Collections.ICollection.CopyTo(ref,int):this (29 methods)
         156 : System.Private.CoreLib.dasm - ReadOnlyCollection`1:System.Collections.ICollection.CopyTo(ref,int):this (26 methods)
         145 : System.Private.CoreLib.dasm - KeyCollection:System.Collections.ICollection.CopyTo(ref,int):this (30 methods)
         145 : System.Private.CoreLib.dasm - ValueCollection:System.Collections.ICollection.CopyTo(ref,int):this (30 methods)
          92 : System.Private.CoreLib.dasm - List`1:FindLastIndex(int,int,ref):int:this (23 methods)
1086 total methods with size differences (0 improved, 1086 regressed), 144430 unchanged.

[erozenfeld]

@dotnet/jit-contrib

[erozenfeld]

The change was suggested by @AndyAyersMS in #17398.

[erozenfeld]

@dotnet-bot test Windows_NT x86 Checked gcstress0xc_zapdisable_jitstress2

[briansull]

LGTM

[AndyAyersMS]

FWIW I think this bug has been around much longer. The existing int3 padding has compensated for it in many cases, though I'd wager with the right set of IBC data we could have found cases where that padding wouldn't kick in properly and we could have seen the same sort of issue.

GC stress failures look to be cases covered by #17330.

[erozenfeld]

@dotnet-bot test CentOS7.1 x64 Checked Innerloop Build and Test

[CarolEidt]

LGTM