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Optimized unresolved static/special glue on X86-64 #4249

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Jan 14, 2019
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Optimized unresolved static/special glue on X86-64 #4249

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45 changes: 26 additions & 19 deletions runtime/compiler/x/runtime/X86Unresolveds.nasm
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
; Copyright (c) 2000, 2018 IBM Corp. and others
; Copyright (c) 2000, 2019 IBM Corp. and others
;
; This program and the accompanying materials are made available under
; the terms of the Eclipse Public License 2.0 which accompanies this
Expand Down Expand Up @@ -1241,29 +1241,26 @@ interpreterUnresolvedStaticGlue:
;
mov rax, qword [rsp] ; p1) rax = RA in mainline code
mov rsi, qword [rdi+12] ; p2) rsi = cpAddr
; 12 = 5 + 5 (call update) + 2 (DW)
; 12 = 5 + 5 (call update) + 2 (DW)
mov edx, dword [rdi+20] ; p3) rdx = cpIndex
; 20 = 5 + 5 (call update) + 2 (DW) + 8 (cpAddr)
CallHelperUseReg jitResolveStaticMethod,rax
; 20 = 5 + 5 (call update) + 2 (DW) + 8 (cpAddr)
call jitResolveStaticMethod
lea rsi, [rdi+5] ; Adjust the return address to "call updateInterpreterDispatchGlueSite"
push rsi ; The RET will mispredict anyway so we can get away with pushing
; the adjusted RA back on the stack.

; The interpreter may low-tag the result to avoid populating the constant pool--whack it.
;
and rax, -2

mergeInterpreterUnresolvedDispatch:
; Load the resolved RAM method into RDI so that the caller doesn't have to re-run patched code
mov rdi, rax

; Patch the call that brought us here into a load of the resolved RAM method into RDI.
;
lea rdi, [rdi-5] ; Adjust the return address to re-run the patched
push rdi ; instruction. The RET will mispredict anyway so we
; can get away with pushing the adjusted RA back on
; the stack.
rol rax, 16
mov ax, 0bf48h ; REX+MOV bytes

mov qword [rdi], rax
ret

shl rax, 16
xor rax, 0bf48h ; REX+MOV bytes
mov qword [rsi-10], rax
ret


Expand All @@ -1275,12 +1272,22 @@ interpreterUnresolvedSpecialGlue:
;
mov rax, qword [rsp] ; p1) rax = RA in mainline code
mov rsi, qword [rdi+12] ; p2) rsi = cpAddr
; 12 = 5 + 5 (call update) + 2 (DW)
; 12 = 5 + 5 (call update) + 2 (DW)
mov edx, dword [rdi+20] ; p3) rdx = cpIndex
; 20 = 5 + 5 (call update) + 2 (DW) + 8 (cpAddr)
CallHelperUseReg jitResolveSpecialMethod,rax
jmp mergeInterpreterUnresolvedDispatch
; 20 = 5 + 5 (call update) + 2 (DW) + 8 (cpAddr)
call jitResolveSpecialMethod
lea rsi, [rdi+5] ; Adjust the return address to "call updateInterpreterDispatchGlueSite"
push rsi ; The RET will mispredict anyway so we can get away with pushing
; the adjusted RA back on the stack.

; Load the resolved RAM method into RDI so that the caller doesn't have to re-run patched code
mov rdi, rax

; Patch the call that brought us here into a load of the resolved RAM method into RDI.
;
shl rax, 16
xor rax, 0bf48h ; REX+MOV bytes
mov qword [rsi-10], rax
ret


Expand Down