PPC: [Interpreter] Make dispatch table point to code entry instead of code objects.

Port 0c05e02f

Original commit message:
    Modifies Ignition to store code entry addresses in the dispatch table
    rather than code objects. This allows the interpreter to avoid
    calculating the code entry address from the code object on every
    dispatch and provides a ~5-7% performance improvement on Octane with
    Ignition.

    This change adds ArchOpcode::kArchTailCallAddress to TurboFan to enable
    tail call dispatch using these code addresses. It also adds a Dispatch
    linkage creator (distinct from the stub linkage type used previously) to
    allow targetting a code address target (which will diverge further from
    the stub linkage type when we remove the context machine register in
    Ignition).

R=rmcilroy@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, bjaideep@ca.ibm.com
BUG=v8:4280
LOG=N

Review URL: https://codereview.chromium.org/1888053002

Cr-Commit-Position: refs/heads/master@{#35501}

src/compiler/ppc/code-generator-ppc.cc

@@ -771,6 +771,14 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       frame_access_state()->ClearSPDelta();
       break;
     }
+    case kArchTailCallAddress: {
+      int stack_param_delta = i.InputInt32(instr->InputCount() - 1);
+      AssembleDeconstructActivationRecord(stack_param_delta);
+      CHECK(!instr->InputAt(0)->IsImmediate());
+      __ Jump(i.InputRegister(0));
+      frame_access_state()->ClearSPDelta();
+      break;
+    }
     case kArchCallJSFunction: {
       v8::internal::Assembler::BlockTrampolinePoolScope block_trampoline_pool(
           masm());

src/ppc/builtins-ppc.cc

@@ -1054,9 +1054,6 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
                          kInterpreterBytecodeOffsetRegister));
   __ ShiftLeftImm(ip, r4, Operand(kPointerSizeLog2));
   __ LoadPX(ip, MemOperand(kInterpreterDispatchTableRegister, ip));
-  // TODO(rmcilroy): Make dispatch table point to code entrys to avoid untagging
-  // and header removal.
-  __ addi(ip, ip, Operand(Code::kHeaderSize - kHeapObjectTag));
   __ Call(ip);
 
   // Even though the first bytecode handler was called, we will never return.
@@ -1185,7 +1182,6 @@ static void Generate_EnterBytecodeDispatch(MacroAssembler* masm) {
                          kInterpreterBytecodeOffsetRegister));
   __ ShiftLeftImm(ip, r4, Operand(kPointerSizeLog2));
   __ LoadPX(ip, MemOperand(kInterpreterDispatchTableRegister, ip));
-  __ addi(ip, ip, Operand(Code::kHeaderSize - kHeapObjectTag));
   __ Jump(ip);
 }