[mips][wasm] Split jump table and lazy compile table

Port 56eaec9d https://crrev.com/c/1698393

Original Commit Message:

    We had both jump slots and lazy compile slots in the same table. This
    increases the space per slot to the maximum of the two, even though we
    often do not use lazy compilation and could have smaller jump slots.
    This CL splits the two into two separate tables. The lazy compile table
    will only be created on demand, and will never be patched.
    The jump table now only contains jumps, and is more compact (which
    might improve performance because of improved locality).

Change-Id: I54a2985d777fd3fa30d420f5af27a3ddc79641b6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1703991Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Yu Yin <xwafish@gmail.com>
Cr-Commit-Position: refs/heads/master@{#62759}

src/wasm/jump-table-assembler.cc

@@ -158,10 +158,14 @@ void JumpTableAssembler::NopBytes(int bytes) {
 #elif V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64
 void JumpTableAssembler::EmitLazyCompileJumpSlot(uint32_t func_index,
                                                  Address lazy_compile_target) {
+  int start = pc_offset();
   li(kWasmCompileLazyFuncIndexRegister, func_index);  // max. 2 instr
   // Jump produces max. 4 instructions for 32-bit platform
   // and max. 6 instructions for 64-bit platform.
   Jump(lazy_compile_target, RelocInfo::NONE);
+  int nop_bytes = start + kLazyCompileTableSlotSize - pc_offset();
+  DCHECK_EQ(nop_bytes % kInstrSize, 0);
+  for (int i = 0; i < nop_bytes; i += kInstrSize) nop();
 }
 
 void JumpTableAssembler::EmitRuntimeStubSlot(Address builtin_target) {

src/wasm/jump-table-assembler.h

@@ -167,14 +167,12 @@ class V8_EXPORT_PRIVATE JumpTableAssembler : public MacroAssembler {
   static constexpr int kJumpTableStubSlotSize = 7 * kInstrSize;
 #elif V8_TARGET_ARCH_MIPS
   static constexpr int kJumpTableLineSize = 6 * kInstrSize;
-  // TODO(mips): Revisit this.
-  static constexpr int kJumpTableSlotSize = 6 * kInstrSize;
+  static constexpr int kJumpTableSlotSize = 4 * kInstrSize;
   static constexpr int kLazyCompileTableSlotSize = 6 * kInstrSize;
   static constexpr int kJumpTableStubSlotSize = 4 * kInstrSize;
 #elif V8_TARGET_ARCH_MIPS64
   static constexpr int kJumpTableLineSize = 8 * kInstrSize;
-  // TODO(mips): Revisit this.
-  static constexpr int kJumpTableSlotSize = 8 * kInstrSize;
+  static constexpr int kJumpTableSlotSize = 6 * kInstrSize;
   static constexpr int kLazyCompileTableSlotSize = 8 * kInstrSize;
   static constexpr int kJumpTableStubSlotSize = 6 * kInstrSize;
 #else