MIPS: Replace JR/JALR with JIC/JIALC for r6

src/mips/assembler-mips.h

Index: src/mips/assembler-mips.h
diff --git a/src/mips/assembler-mips.h b/src/mips/assembler-mips.h
index fbeed471610211a67091e50244f73b5881314c7e..15783f4f233d6b64a064c71a7902993b80a90246 100644
--- a/src/mips/assembler-mips.h
+++ b/src/mips/assembler-mips.h
@@ -524,8 +524,13 @@ class Assembler : public AssemblerBase {
   // the instruction that follows LUI/ORI instruction pair. Now, with new jump
   // optimization, where jump-through-register instruction that usually
   // follows LUI/ORI pair is substituted with J/JAL, this constant equals

[paul.l..., 2016/01/11 22:34:57]

These comments about J/JAL should have been removed in
https://codereview.chromium.org/1419793014. Please remove them now.

[miran.karic, 2016/02/18 08:38:05]

Done.

-  // to 3 instructions (LUI+ORI+J/JAL/JR/JALR).
+// to 3 instructions (LUI+ORI+J/JAL/JR/JALR). On r6, 32bit constant is placed
+// in 2 instructions (LUI+JIC)
+#ifdef _MIPS_ARCH_MIPS32R6
+  static const int kInstructionsFor32BitConstant = 2;
+#else
   static const int kInstructionsFor32BitConstant = 3;

[paul.l..., 2016/01/11 22:34:57]

I _think_ this case of 3 was only useful when we had J/JAL optimization. I think
we should use 2 now everywhere. However, we must be certain that all tests work,
with and without snapshots on sim and board. It might be prudent to remove all
this cruft, and test/submit in a separate CL from this JIC work.

[miran.karic, 2016/02/18 08:38:05]

Done. New CL created.

+#endif
 
   // Distance between the instruction referring to the address of the call
   // target and the return address.
@@ -1086,6 +1091,7 @@ class Assembler : public AssemblerBase {
   static bool IsBnezc(Instr instr);
   static bool IsBeqc(Instr instr);
   static bool IsBnec(Instr instr);
+  static bool IsJicOrJialc(Instr instr);
 
   static bool IsJump(Instr instr);
   static bool IsJ(Instr instr);
@@ -1125,12 +1131,20 @@ class Assembler : public AssemblerBase {
   static int32_t GetBranchOffset(Instr instr);
   static bool IsLw(Instr instr);
   static int16_t GetLwOffset(Instr instr);
+  static int16_t GetJicOrJialcOffset(Instr instr);
+  static int16_t GetLuiOffset(Instr instr);
   static Instr SetLwOffset(Instr instr, int16_t offset);
 
   static bool IsSw(Instr instr);
   static Instr SetSwOffset(Instr instr, int16_t offset);
   static bool IsAddImmediate(Instr instr);
   static Instr SetAddImmediateOffset(Instr instr, int16_t offset);
+  static uint32_t createTargetAddress(Instr instr_lui, Instr instr_jic);
+  static void unpackTargetAddress(uint32_t address, int16_t& lui_offset,
+                                  int16_t& jic_offset);
+  static void unpackTargetAddressUnsigned(uint32_t address,
+                                          uint32_t& lui_offset,
+                                          uint32_t& jic_offset);
 
   static bool IsAndImmediate(Instr instr);
   static bool IsEmittedConstant(Instr instr);
@@ -1211,6 +1225,8 @@ class Assembler : public AssemblerBase {
 
   inline void CheckTrampolinePoolQuick(int extra_instructions = 0);
 
+  inline void CheckBuffer();
+
  private:
   inline static void set_target_internal_reference_encoded_at(Address pc,
                                                               Address target);
@@ -1257,7 +1273,6 @@ class Assembler : public AssemblerBase {
   enum class CompactBranchType : bool { NO = false, COMPACT_BRANCH = true };
 
   // Code emission.
-  inline void CheckBuffer();
   void GrowBuffer();
   inline void emit(Instr x,
                    CompactBranchType is_compact_branch = CompactBranchType::NO);
@@ -1399,7 +1414,11 @@ class Assembler : public AssemblerBase {
   // branch instruction generation, where we use jump instructions rather
   // than regular branch instructions.
   bool trampoline_emitted_;
+#ifdef _MIPS_ARCH_MIPS32R6
+  static const int kTrampolineSlotsSize = 2 * kInstrSize;
+#else
   static const int kTrampolineSlotsSize = 4 * kInstrSize;
+#endif
   static const int kMaxBranchOffset = (1 << (18 - 1)) - 1;
   static const int kMaxCompactBranchOffset = (1 << (28 - 1)) - 1;
   static const int kInvalidSlotPos = -1;