MIPS64: Improve integer division by constants

This also removes some unused instructions and instructions not
available on MIPS64R6.

Change-Id: I44bfe12c60344312c88c45e97b6b07dcd5bdc630
diff --git a/compiler/utils/mips64/assembler_mips64.cc b/compiler/utils/mips64/assembler_mips64.cc
index 00e8995..8e9b509 100644
--- a/compiler/utils/mips64/assembler_mips64.cc
+++ b/compiler/utils/mips64/assembler_mips64.cc
@@ -117,14 +117,6 @@
   Emit(encoding);
 }
 
-void Mips64Assembler::Add(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
-  EmitR(0, rs, rt, rd, 0, 0x20);
-}
-
-void Mips64Assembler::Addi(GpuRegister rt, GpuRegister rs, uint16_t imm16) {
-  EmitI(0x8, rs, rt, imm16);
-}
-
 void Mips64Assembler::Addu(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
   EmitR(0, rs, rt, rd, 0, 0x21);
 }
@@ -141,10 +133,6 @@
   EmitI(0x19, rs, rt, imm16);
 }
 
-void Mips64Assembler::Sub(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
-  EmitR(0, rs, rt, rd, 0, 0x22);
-}
-
 void Mips64Assembler::Subu(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
   EmitR(0, rs, rt, rd, 0, 0x23);
 }
@@ -153,50 +141,14 @@
   EmitR(0, rs, rt, rd, 0, 0x2f);
 }
 
-void Mips64Assembler::MultR2(GpuRegister rs, GpuRegister rt) {
-  EmitR(0, rs, rt, static_cast<GpuRegister>(0), 0, 0x18);
-}
-
-void Mips64Assembler::MultuR2(GpuRegister rs, GpuRegister rt) {
-  EmitR(0, rs, rt, static_cast<GpuRegister>(0), 0, 0x19);
-}
-
-void Mips64Assembler::DivR2(GpuRegister rs, GpuRegister rt) {
-  EmitR(0, rs, rt, static_cast<GpuRegister>(0), 0, 0x1a);
-}
-
-void Mips64Assembler::DivuR2(GpuRegister rs, GpuRegister rt) {
-  EmitR(0, rs, rt, static_cast<GpuRegister>(0), 0, 0x1b);
-}
-
-void Mips64Assembler::MulR2(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
-  EmitR(0x1c, rs, rt, rd, 0, 2);
-}
-
-void Mips64Assembler::DivR2(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
-  DivR2(rs, rt);
-  Mflo(rd);
-}
-
-void Mips64Assembler::ModR2(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
-  DivR2(rs, rt);
-  Mfhi(rd);
-}
-
-void Mips64Assembler::DivuR2(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
-  DivuR2(rs, rt);
-  Mflo(rd);
-}
-
-void Mips64Assembler::ModuR2(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
-  DivuR2(rs, rt);
-  Mfhi(rd);
-}
-
 void Mips64Assembler::MulR6(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
   EmitR(0, rs, rt, rd, 2, 0x18);
 }
 
+void Mips64Assembler::MuhR6(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
+  EmitR(0, rs, rt, rd, 3, 0x18);
+}
+
 void Mips64Assembler::DivR6(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
   EmitR(0, rs, rt, rd, 2, 0x1a);
 }
@@ -217,6 +169,10 @@
   EmitR(0, rs, rt, rd, 2, 0x1c);
 }
 
+void Mips64Assembler::Dmuh(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
+  EmitR(0, rs, rt, rd, 3, 0x1c);
+}
+
 void Mips64Assembler::Ddiv(GpuRegister rd, GpuRegister rs, GpuRegister rt) {
   EmitR(0, rs, rt, rd, 2, 0x1e);
 }
@@ -440,14 +396,6 @@
            static_cast<GpuRegister>(0), stype & 0x1f, 0xf);
 }
 
-void Mips64Assembler::Mfhi(GpuRegister rd) {
-  EmitR(0, static_cast<GpuRegister>(0), static_cast<GpuRegister>(0), rd, 0, 0x10);
-}
-
-void Mips64Assembler::Mflo(GpuRegister rd) {
-  EmitR(0, static_cast<GpuRegister>(0), static_cast<GpuRegister>(0), rd, 0, 0x12);
-}
-
 void Mips64Assembler::Sb(GpuRegister rt, GpuRegister rs, uint16_t imm16) {
   EmitI(0x28, rs, rt, imm16);
 }