Improved Exception handling

[benaadams]

Throw the exceptions directly from the void method, don't mark as no-inlining

Post dotnet/coreclr#6103 "Do not inline methods that never return" this will give the best result. (As shown in dotnet/coreclr#6634)

It won't inline the exception Throw function, will mark the call to the Throw function as cold code, and won't preform any register prep for the function (push+pop)

[benaadams]

e.g. public static void Requires(bool condition)

Pre

Inlines into 06000001 Contract:Requires(bool)
  [0 IL=0003 TR=000010 06000009] [FAILED: noinline per IL/cached result] Contract:NewArgumentException():ref
Budget: initialTime=90, finalTime=90, initialBudget=900, currentBudget=900
Budget: initialSize=359, finalSize=359

; Assembly listing for method Contract:Requires(bool)
; Emitting BLENDED_CODE for X64 CPU with SSE2
; optimized code
; rsp based frame
; partially interruptible
; Final local variable assignments
;
;  V00 arg0         [V00,T00] (  3,   3  )    bool  ->  rcx        
;  V01 OutArgs      [V01    ] (  1,   1  )  lclBlk (32) [rsp+0x00]  
;
; Lcl frame size = 40
G_M36318_IG01:
       sub      rsp, 40
       nop      
G_M36318_IG02:
       test     cl, cl
       je       SHORT G_M36318_IG04
G_M36318_IG03:
       add      rsp, 40
       ret      
G_M36318_IG04:
       call     [Contract:NewArgumentException():ref]
       mov      rcx, rax
       call     CORINFO_HELP_THROW
       int3     
; Total bytes of code 29, prolog size 5 for method Contract:Requires(bool)

Post

Inlines into 06000001 Contract:Requires(bool)
  [0 IL=0003 TR=000010 06000009] [FAILED: does not return] Contract:ThrowArgumentException()
Budget: initialTime=87, finalTime=87, initialBudget=870, currentBudget=870
Budget: initialSize=336, finalSize=336

; Assembly listing for method Contract:Requires(bool)
; Emitting BLENDED_CODE for X64 CPU with SSE2
; optimized code
; rsp based frame
; partially interruptible
; Final local variable assignments
;
;  V00 arg0         [V00,T00] (  3,   3  )    bool  ->  rcx        
;  V01 OutArgs      [V01    ] (  1,   1  )  lclBlk (32) [rsp+0x00]  
;
; Lcl frame size = 40
G_M36319_IG01:
       sub      rsp, 40
       nop      
G_M36319_IG02:
       test     cl, cl
       je       SHORT G_M36319_IG04
G_M36319_IG03:
       add      rsp, 40
       ret      
G_M36319_IG04:
       call     [Contract:ThrowArgumentException()]
       int3     
; Total bytes of code 21, prolog size 5 for method Contract:Requires(bool)

[benaadams]

Likewise it means: Span`1:.ctor(ref):this

ends like

       ret      
G_M44205_IG06:
       call     [Contract:ThrowArgumentException()]
G_M44205_IG07:
       call     [Contract:ThrowArgumentException()]
       int3     
; Total bytes of code 137, prolog size 13 for method Span`1:.ctor(ref):this

instead of

       ret      
G_M44203_IG06:
       call     [Contract:NewArgumentException():ref]
       mov      rcx, rax
       call     CORINFO_HELP_THROW
G_M44203_IG07:
       call     [Contract:NewArgumentException():ref]
       mov      rcx, rax
       call     CORINFO_HELP_THROW
       int3     
; Total bytes of code 153, prolog size 13 for method Span`1:.ctor(ref):this

[KrzysztofCwalina]

@dotnet-bot test this please

[KrzysztofCwalina]

Thanks!