Fix INVALIDGCVALUE on Unix

[platform/upstream/coreclr.git] / src / vm / amd64 / jithelpers_fast.S

diff --git a/src/vm/amd64/jithelpers_fast.S b/src/vm/amd64/jithelpers_fast.S
index a981254..22f21bb 100644 (file)
--- a/src/vm/amd64/jithelpers_fast.S
+++ b/src/vm/amd64/jithelpers_fast.S
@@ -1,7 +1,6 @@
-//
-// Copyright (c) Microsoft. All rights reserved.
-// Licensed under the MIT license. See LICENSE file in the project root for full license information. 
-//
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
 
 .intel_syntax noprefix
 #include "unixasmmacros.inc"
@@ -122,11 +121,18 @@ LEAF_END_MARKED JIT_CheckedWriteBarrier, _TEXT
 // Entry:
 //   RDI - address of ref-field (assigned to)
 //   RSI - address of the data  (source)
-//   RCX can be trashed
+//
+//   Note: RyuJIT assumes that all volatile registers can be trashed by
+//   the CORINFO_HELP_ASSIGN_BYREF helper (i.e. JIT_ByRefWriteBarrier).
+//   The precise set is defined by RBM_CALLEE_TRASH.
+//
+//   RCX is trashed
+//   RAX is trashed
+//   R10 is trashed on Debug build
+//   R11 is trashed on Debug build
 // Exit:
 //   RDI, RSI are incremented by SIZEOF(LPVOID)
 LEAF_ENTRY JIT_ByRefWriteBarrier, _TEXT
-        push    rax
         mov     rcx, [rsi]
 
 // If !WRITE_BARRIER_CHECK do the write first, otherwise we might have to do some ShadowGC stuff
@@ -147,11 +153,6 @@ LEAF_ENTRY JIT_ByRefWriteBarrier, _TEXT
         jnb     NotInHeap_ByRefWriteBarrier
 
 #ifdef WRITE_BARRIER_CHECK
-        // we can only trash rcx in this function so in _DEBUG we need to save
-        // some scratch registers.
-        push    r10
-        push    r11
-
         // **ALSO update the shadow GC heap if that is enabled**
         // Do not perform the work if g_GCShadow is 0
         PREPARE_EXTERNAL_VAR g_GCShadow, rax
@@ -185,7 +186,7 @@ LEAF_ENTRY JIT_ByRefWriteBarrier, _TEXT
         mov     rax, [r10]
         cmp     rax, r11
         je      DoneShadow_ByRefWriteBarrier
-        mov     r11, INVALIDGCVALUE
+        movabs  r11, INVALIDGCVALUE
         mov     [r10], r11
 
         jmp     DoneShadow_ByRefWriteBarrier
@@ -199,8 +200,6 @@ LEAF_ENTRY JIT_ByRefWriteBarrier, _TEXT
     // Additionally we know for sure that we are inside the heap and therefore don't
     // need to replicate the above checks.
     DoneShadow_ByRefWriteBarrier:
-        pop     r11
-        pop     r10
 #endif
 
         // See if we can just quick out
@@ -222,8 +221,6 @@ LEAF_ENTRY JIT_ByRefWriteBarrier, _TEXT
         PREPARE_EXTERNAL_VAR g_card_table, rax
         add     rcx, [rax]
 
-        pop     rax
-        
         // Check if this card is dirty
         cmp     byte ptr [rcx], 0FFh
         jne     UpdateCardTable_ByRefWriteBarrier
@@ -246,6 +243,5 @@ LEAF_ENTRY JIT_ByRefWriteBarrier, _TEXT
         // Increment the pointers before leaving
         add     rdi, 8h
         add     rsi, 8h
-        pop     rax
         ret
 LEAF_END JIT_ByRefWriteBarrier, _TEXT