PPC: [turbofan] Better and more sane support for tail calls

Port ff283f7d

Original commit message:
    * Limit triggering of tail calls to explicit use of a new inline runtime
      function %_TailCall. %_TailCall works just like %_Call except for using
      tail-calling mechanics (currently only in TF).
    * Remove hack that recognized some specific usages of %_Call and converted them
      into tail calls.
    * Support tail calls for all calls where the number of callee stack parameters
      is less than or equal to the number of caller stack parameters.
    * Use the gap resolver to swizzle parameters and registers to tail calls.

R=danno@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, dstence@us.ibm.com
BUG=v8:4076
LOG=n

Review URL: https://codereview.chromium.org/1442143002

Cr-Commit-Position: refs/heads/master@{#31994}

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

@@ -605,11 +605,15 @@ Condition FlagsConditionToCondition(FlagsCondition condition) {
   } while (0)
 
 
-void CodeGenerator::AssembleDeconstructActivationRecord() {
+void CodeGenerator::AssembleDeconstructActivationRecord(int stack_param_delta) {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
   int stack_slots = frame()->GetSpillSlotCount();
+  int sp_delta =
+      (stack_param_delta < 0) ? -stack_param_delta * kPointerSize : 0;
   if (descriptor->IsJSFunctionCall() || stack_slots > 0) {
-    __ LeaveFrame(StackFrame::MANUAL);
+    __ LeaveFrame(StackFrame::MANUAL, sp_delta);
+  } else if (sp_delta) {
+    __ Add(sp, sp, sp_delta, r0);
   }
 }
 
@@ -637,7 +641,8 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       break;
     }
     case kArchTailCallCodeObject: {
-      AssembleDeconstructActivationRecord();
+      int stack_param_delta = i.InputInt32(instr->InputCount() - 1);
+      AssembleDeconstructActivationRecord(stack_param_delta);
       if (HasRegisterInput(instr, 0)) {
         __ addi(ip, i.InputRegister(0),
                 Operand(Code::kHeaderSize - kHeapObjectTag));
@@ -679,7 +684,8 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
         __ cmp(cp, kScratchReg);
         __ Assert(eq, kWrongFunctionContext);
       }
-      AssembleDeconstructActivationRecord();
+      int stack_param_delta = i.InputInt32(instr->InputCount() - 1);
+      AssembleDeconstructActivationRecord(stack_param_delta);
       __ LoadP(ip, FieldMemOperand(func, JSFunction::kCodeEntryOffset));
       __ Jump(ip);
       DCHECK_EQ(LeaveRC, i.OutputRCBit());