Few cleanups in nterp.

- No need to manually save the ArtMethod, it's already saved in
SPILL_ALL_ARGUMENTS
- Remove unused parameter to SET_VREG_OBJECT
- Fix comment on common_errArrayIndex

Test: test.py
Bug: 112676029
Change-Id: I012a2ccac96c175be6107e762c620b7d5eba8f1c
diff --git a/runtime/interpreter/mterp/arm64ng/main.S b/runtime/interpreter/mterp/arm64ng/main.S
index 2dbfe58..a0a00a7 100644
--- a/runtime/interpreter/mterp/arm64ng/main.S
+++ b/runtime/interpreter/mterp/arm64ng/main.S
@@ -202,7 +202,7 @@
     str     \reg, [xFP, \vreg, uxtw #2]
     str     wzr, [xREFS, \vreg, uxtw #2]
 .endm
-.macro SET_VREG_OBJECT reg, vreg, tmpreg
+.macro SET_VREG_OBJECT reg, vreg
     str     \reg, [xFP, \vreg, uxtw #2]
     str     \reg, [xREFS, \vreg, uxtw #2]
 .endm
@@ -1546,14 +1546,12 @@
     // TODO: Get shorty in a better way and remove below
     SPILL_ALL_ARGUMENTS
 
-    // Save method in callee-save xINST
-    mov xINST, x0
     bl NterpGetShorty
     // Save shorty in callee-save xIBASE.
     mov xIBASE, x0
 
     RESTORE_ALL_ARGUMENTS
-    ldr xPC, [xINST, #ART_METHOD_DATA_OFFSET_64]
+    ldr xPC, [x0, #ART_METHOD_DATA_OFFSET_64]
 
     // Setup the stack for executing the method.
     SETUP_STACK_FRAME xPC, xREFS, xFP, CFI_REFS, load_ins=1
@@ -1632,7 +1630,7 @@
     EXPORT_PC
     bl art_quick_throw_div_zero
 
-// Expect array in w0, index in w1, length in w2
+// Expect index in w1, length in w3.
 common_errArrayIndex:
     EXPORT_PC
     mov x0, x1
@@ -1844,7 +1842,7 @@
    ldr w0, [x0, #ART_FIELD_DECLARING_CLASS_OFFSET]
    cbnz wMR, 7f
 6:
-   lsr w2, wINST, #8                    // w1 <- A
+   lsr w2, wINST, #8                    // w2 <- A
    GET_VREG w2, w2
    add ip, x0, x1
    stlr w2, [ip]
@@ -2005,7 +2003,7 @@
    cbnz wMR, 4f
 1:
    lsr     w2, wINST, #8               // w2<- A
-   GET_VREG w0, w2                     // w2<- vA (object)
+   GET_VREG w0, w2                     // w0<- vA (object)
    cbz w0, 2f
    bl art_quick_check_instance_of
 2:
diff --git a/runtime/interpreter/mterp/arm64ng/other.S b/runtime/interpreter/mterp/arm64ng/other.S
index d7efe28..56a8086 100644
--- a/runtime/interpreter/mterp/arm64ng/other.S
+++ b/runtime/interpreter/mterp/arm64ng/other.S
@@ -228,7 +228,7 @@
     FETCH_ADVANCE_INST 1                // advance rPC, load wINST
     GET_INST_OPCODE ip                  // extract opcode from wINST
     .if $is_object
-    SET_VREG_OBJECT w0, w2, w1          // fp[AA]<- r0
+    SET_VREG_OBJECT w0, w2              // fp[AA]<- r0
     .else
     SET_VREG w0, w2                     // fp[AA]<- r0
     .endif
diff --git a/runtime/interpreter/mterp/x86_64ng/main.S b/runtime/interpreter/mterp/x86_64ng/main.S
index 2025696..7a8fe6e 100644
--- a/runtime/interpreter/mterp/x86_64ng/main.S
+++ b/runtime/interpreter/mterp/x86_64ng/main.S
@@ -1462,8 +1462,6 @@
     movq %xmm6, 48(%rsp)
     movq %xmm7, 56(%rsp)
 
-    // Save method in callee-save rbx.
-    movq %rdi, %rbx
     call SYMBOL(NterpGetShorty)
     // Save shorty in callee-save rbp.
     movq %rax, %rbp
@@ -1567,6 +1565,7 @@
     EXPORT_PC
     call art_quick_throw_div_zero
 
+// Expect array in edi, index in esi.
 common_errArrayIndex:
     EXPORT_PC
     movl MIRROR_ARRAY_LENGTH_OFFSET(%edi), %eax