ARM64: optimize PREPARE_EXTERNAL_VAR (#21)

src/Native/Runtime/arm64/ExceptionHandling.S

@@ -465,9 +465,8 @@ PopExInfoLoop:
 DonePopping:
         str         x3, [x1, #OFFSETOF__Thread__m_pExInfoStackHead]     // store the new head on the Thread
 
-        PREPARE_EXTERNAL_VAR RhpTrapThreads, x3 
+        PREPARE_EXTERNAL_VAR_INDIRECT_W RhpTrapThreads, 3 
 
-        ldr         w3, [x3]
         tbz         x3, #TrapThreadsFlags_AbortInProgress_Bit, NoAbort
 
         ldr         x3, [sp, #rsp_offset_is_not_handling_thread_abort]

src/Native/Runtime/arm64/InteropThunksHelpers.S

@@ -40,8 +40,7 @@ POINTER_SIZE = 0x08
     // IntPtr RhGetCommonStubAddress()
     //
     LEAF_ENTRY RhGetCommonStubAddress, _TEXT
-        adrp x0, RhCommonStub
-        add	x0, x0, :lo12:RhCommonStub
+        PREPARE_EXTERNAL_VAR RhCommonStub, x0
         ret
     LEAF_END RhGetCommonStubAddress, _TEXT
 

src/Native/Runtime/arm64/PInvoke.S

@@ -118,9 +118,8 @@ Done:
 
         PROLOG_SAVE_REG_PAIR_INDEXED    fp, lr, #-0x10
 
-        PREPARE_EXTERNAL_VAR RhpTrapThreads, x10
+        PREPARE_EXTERNAL_VAR_INDIRECT_W RhpTrapThreads, 10
 
-        ldr         w10, [x10]
         tbz         x10, #TrapThreadsFlags_TrapThreads_Bit, NoWait
         bl          RhpWaitForGCNoAbort
 NoWait:
@@ -181,9 +180,8 @@ ThreadAttached:
         str         xzr, [x10, #OFFSETOF__Thread__m_pTransitionFrame] 
         dmb         ish
 
-        PREPARE_EXTERNAL_VAR RhpTrapThreads, x11
+        PREPARE_EXTERNAL_VAR_INDIRECT_W RhpTrapThreads, 11
 
-        ldr         w11, [x11]
         tbnz        x11, #TrapThreadsFlags_TrapThreads_Bit, TrapThread
 
         ret
@@ -294,9 +292,8 @@ NESTED_ENTRY RhpPInvoke, _TEXT, NoHandler
         str     x10, [x0, #OFFSETOF__PInvokeTransitionFrame__m_pThread]
         str     x0, [x10, #OFFSETOF__Thread__m_pTransitionFrame]
 
-        PREPARE_EXTERNAL_VAR RhpTrapThreads, x9
+        PREPARE_EXTERNAL_VAR_INDIRECT_W RhpTrapThreads, 9
 
-        ldr     w9, [x9]
         cbnz    w9, InvokeRareTrapThread  // TrapThreadsFlags_None = 0
         ret
 
@@ -310,9 +307,8 @@ LEAF_ENTRY RhpPInvokeReturn, _TEXT
         mov         x10, 0
         str         x10, [x9, #OFFSETOF__Thread__m_pTransitionFrame]
 
-        PREPARE_EXTERNAL_VAR RhpTrapThreads, x9
+        PREPARE_EXTERNAL_VAR_INDIRECT_W RhpTrapThreads, 9
 
-        ldr     w9, [x9]
         cbnz    w9, 0f  // TrapThreadsFlags_None = 0
         ret
 0:

src/Native/Runtime/arm64/StubDispatch.S

@@ -99,8 +99,7 @@
         // Calling convention of the universal thunk is:
         //  xip0: contains target address for the thunk to call
         //  xip1: contains parameter of the thunks target
-        adrp xip0, RhpCidResolve
-        add	xip0, xip0, :lo12:RhpCidResolve
+        PREPARE_EXTERNAL_VAR RhpCidResolve, xip0
         mov xip1, x11
         b       RhpUniversalTransition_DebugStepTailCall
     LEAF_END RhpInterfaceDispatchSlow, _TEXT

src/Native/Runtime/arm64/WriteBarriers.S

@@ -28,26 +28,22 @@
         .macro UPDATE_GC_SHADOW destReg, refReg
 
         // If g_GCShadow is 0, don't perform the check.
-        PREPARE_EXTERNAL_VAR g_GCShadow, X9
-        ldr     x9, [x9]
+        PREPARE_EXTERNAL_VAR_INDIRECT g_GCShadow, X9
         cbz     x9, 1f
 
         // Save destReg since we're about to modify it (and we need the original value both within the macro and
         // once we exit the macro).
         mov     x10, \destReg
 
         // Transform destReg into the equivalent address in the shadow heap.
-        PREPARE_EXTERNAL_VAR g_lowest_address, X9
-        ldr     x9, [x9]
+        PREPARE_EXTERNAL_VAR_INDIRECT g_lowest_address, X9
         subs    \destReg, \destReg, x9
         blt     0f
 
-        PREPARE_EXTERNAL_VAR g_GCShadow, X9
-        ldr     x9, [x9]
+        PREPARE_EXTERNAL_VAR_INDIRECT g_GCShadow, X9
         add     \destReg, \destReg, x9
 
-        PREPARE_EXTERNAL_VAR g_GCShadowEnd, X9
-        ldr     x9, [x9]
+        PREPARE_EXTERNAL_VAR_INDIRECT g_GCShadowEnd, X9
         cmp     \destReg, x9
         bgt     0f
 
@@ -109,8 +105,8 @@
 
 #ifdef FEATURE_USE_SOFTWARE_WRITE_WATCH_FOR_GC_HEAP
         // Update the write watch table if necessary
-        PREPARE_EXTERNAL_VAR g_write_watch_table, x\trash
-        ldr  x\trash, [x\trash]
+        PREPARE_EXTERNAL_VAR_INDIRECT g_write_watch_table, x\trash
+
         cbz  x\trash, 2f
         add  x\trash, x\trash, \destReg, lsr #0xc  // SoftwareWriteWatch::AddressToTableByteIndexShift
         ldrb w17, [x\trash]
@@ -122,20 +118,17 @@
 2:
         // We can skip the card table write if the reference is to
         // an object not on the epehemeral segment.
-        PREPARE_EXTERNAL_VAR g_ephemeral_low, x\trash
-        ldr     x\trash, [x\trash]
+        PREPARE_EXTERNAL_VAR_INDIRECT g_ephemeral_low, x\trash
         cmp     \refReg, x\trash
         blt     0f
 
-        PREPARE_EXTERNAL_VAR g_ephemeral_high, x\trash
-        ldr     x\trash, [x\trash]
+        PREPARE_EXTERNAL_VAR_INDIRECT g_ephemeral_high, x\trash
         cmp     \refReg, x\trash
         bge     0f
 
         // Set this objects card, if it has not already been set.
 
-        PREPARE_EXTERNAL_VAR g_card_table, x\trash
-        ldr     x\trash, [x\trash]
+        PREPARE_EXTERNAL_VAR_INDIRECT g_card_table, x\trash
         add     \trash2, x\trash, \destReg, lsr #11
 
         // Check that this card has not already been written. Avoiding useless writes is a big win on
@@ -149,8 +142,7 @@
 
 #ifdef FEATURE_MANUALLY_MANAGED_CARD_BUNDLES
         // Check if we need to update the card bundle table
-        PREPARE_EXTERNAL_VAR g_card_bundle_table, x\trash
-        ldr     x\trash, [x\trash]
+        PREPARE_EXTERNAL_VAR_INDIRECT g_card_bundle_table, x\trash
         add  \trash2, x\trash, \destReg, lsr #21
         ldrb w\trash, [\trash2]
         cmp  x\trash, 0xFF
@@ -178,13 +170,11 @@
         // The "check" of this checked write barrier - is destReg
         // within the heap? if no, early out.
 
-        PREPARE_EXTERNAL_VAR g_lowest_address, x\trash
-        ldr     x\trash, [x\trash]
+        PREPARE_EXTERNAL_VAR_INDIRECT g_lowest_address, x\trash
         cmp     \destReg, x\trash
         blt     0f
 
-        PREPARE_EXTERNAL_VAR g_highest_address, x\trash
-        ldr     x\trash, [x\trash]
+        PREPARE_EXTERNAL_VAR_INDIRECT g_highest_address, x\trash
         cmp     \destReg, x\trash
         bgt     0f
 

src/Native/Runtime/unix/unixasmmacrosarm64.inc

@@ -46,6 +46,17 @@ C_FUNC(\Name):
         add	\HelperReg, \HelperReg, :lo12:C_FUNC(\Name)
 .endm 
 
+.macro PREPARE_EXTERNAL_VAR_INDIRECT Name, HelperReg
+        adrp \HelperReg, C_FUNC(\Name)
+        ldr	\HelperReg, [\HelperReg, :lo12:C_FUNC(\Name)]
+.endm 
+
+.macro PREPARE_EXTERNAL_VAR_INDIRECT_W Name, HelperReg
+        adrp x\HelperReg, C_FUNC(\Name)
+        ldr	w\HelperReg, [x\HelperReg, :lo12:C_FUNC(\Name)]
+.endm 
+
+
 .macro PROLOG_STACK_ALLOC Size
         sub sp, sp, \Size
         .cfi_adjust_cfa_offset \Size