MIPS32: Improve and moderately clean up mterp.

Improvements:
- use seb, seh, ins on R2+
- use lsa, trunc.l.(s|d), cvt.(s|d).l, jic on R6
- shorter float/double comparison
- shorter float/double to int/long conversion
- fewer memory reads in float/double to int/long conversion
- remove unnecessary %break's and branches across breaks
- use branch delay slots more efficiently on R2

Test: booted MIPS32R2 in QEMU
Test: test-art-target-run-test-interpreter (MIPS32R2) on CI20
Test: booted MIPS64 (with 2nd arch MIPS32R6) in QEMU
Test: test-art-target-run-test-interpreter (MIPS32R6) in QEMU

Change-Id: I9959bec08e20c2423deae31f71b523ad36b4be9a
diff --git a/runtime/interpreter/mterp/mips/fbinop2addr.S b/runtime/interpreter/mterp/mips/fbinop2addr.S
index ccb67b1..2caaf9c 100644
--- a/runtime/interpreter/mterp/mips/fbinop2addr.S
+++ b/runtime/interpreter/mterp/mips/fbinop2addr.S
@@ -1,19 +1,18 @@
     /*
      * Generic 32-bit "/2addr" binary operation.  Provide an "instr"
-     * that specifies an instruction that performs "result = a0 op a1".
+     * that specifies an instruction that performs "fv0 = fa0 op fa1".
      * This could be an MIPS instruction or a function call.
      *
      * For: add-float/2addr, sub-float/2addr, mul-float/2addr,
-     * div-float/2addr, rem-float/2addr
+     *      div-float/2addr, rem-float/2addr
      */
     /* binop/2addr vA, vB */
-    GET_OPA4(rOBJ)                         #  t1 <- A+
+    GET_OPA4(rOBJ)                         #  rOBJ <- A+
     GET_OPB(a3)                            #  a3 <- B
     GET_VREG_F(fa0, rOBJ)
     GET_VREG_F(fa1, a3)
     FETCH_ADVANCE_INST(1)                  #  advance rPC, load rINST
 
     $instr
-    SET_VREG_F(fv0, rOBJ)                  #  vAA <- result
     GET_INST_OPCODE(t0)                    #  extract opcode from rINST
-    GOTO_OPCODE(t0)                        #  jump to next instruction
+    SET_VREG_F_GOTO(fv0, rOBJ, t0)         #  vA <- result