[ppc] Port native routines to use UseScratchRegisterScope

Change-Id: I8034f64ba412a7d880fdc1b7bc4dce0b41fe3114
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1696915Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#62786}

src/codegen/ppc/assembler-ppc.cc

@@ -224,6 +224,7 @@ void Assembler::AllocateAndInstallRequestedHeapObjects(Isolate* isolate) {
 Assembler::Assembler(const AssemblerOptions& options,
                      std::unique_ptr<AssemblerBuffer> buffer)
     : AssemblerBase(options, std::move(buffer)),
+      scratch_register_list_(ip.bit()),
       constant_pool_builder_(kLoadPtrMaxReachBits, kLoadDoubleMaxReachBits) {
   reloc_info_writer.Reposition(buffer_start_ + buffer_->size(), pc_);
 
@@ -1947,6 +1948,24 @@ PatchingAssembler::~PatchingAssembler() {
   DCHECK_EQ(reloc_info_writer.pos(), buffer_start_ + buffer_->size());
 }
 
+UseScratchRegisterScope::UseScratchRegisterScope(Assembler* assembler)
+    : assembler_(assembler),
+      old_available_(*assembler->GetScratchRegisterList()) {}
+
+UseScratchRegisterScope::~UseScratchRegisterScope() {
+  *assembler_->GetScratchRegisterList() = old_available_;
+}
+
+Register UseScratchRegisterScope::Acquire() {
+  RegList* available = assembler_->GetScratchRegisterList();
+  DCHECK_NOT_NULL(available);
+  DCHECK_NE(*available, 0);
+  int index = static_cast<int>(base::bits::CountTrailingZeros32(*available));
+  Register reg = Register::from_code(index);
+  *available &= ~reg.bit();
+  return reg;
+}
+
 }  // namespace internal
 }  // namespace v8
 

src/codegen/ppc/assembler-ppc.h

@@ -437,6 +437,7 @@ class Assembler : public AssemblerBase {
   PPC_XX3_OPCODE_LIST(DECLARE_PPC_XX3_INSTRUCTIONS)
 #undef DECLARE_PPC_XX3_INSTRUCTIONS
 
+  RegList* GetScratchRegisterList() { return &scratch_register_list_; }
   // ---------------------------------------------------------------------------
   // Code generation
 
@@ -1182,6 +1183,9 @@ class Assembler : public AssemblerBase {
   static constexpr int kMaxRelocSize = RelocInfoWriter::kMaxSize;
   std::vector<DeferredRelocInfo> relocations_;
 
+  // Scratch registers available for use by the Assembler.
+  RegList scratch_register_list_;
+
   // The bound position, before this we cannot do instruction elimination.
   int last_bound_pos_;
   // Optimizable cmpi information.
@@ -1297,6 +1301,7 @@ class Assembler : public AssemblerBase {
   friend class RelocInfo;
   friend class BlockTrampolinePoolScope;
   friend class EnsureSpace;
+  friend class UseScratchRegisterScope;
 };
 
 class EnsureSpace {
@@ -1311,6 +1316,24 @@ class PatchingAssembler : public Assembler {
   ~PatchingAssembler();
 };
 
+class V8_EXPORT_PRIVATE UseScratchRegisterScope {
+ public:
+  explicit UseScratchRegisterScope(Assembler* assembler);
+  ~UseScratchRegisterScope();
+
+  Register Acquire();
+
+  // Check if we have registers available to acquire.
+  bool CanAcquire() const { return *assembler_->GetScratchRegisterList() != 0; }
+
+ private:
+  friend class Assembler;
+  friend class TurboAssembler;
+
+  Assembler* assembler_;
+  RegList old_available_;
+};
+
 }  // namespace internal
 }  // namespace v8
 

src/deoptimizer/ppc/deoptimizer-ppc.cc

@@ -56,11 +56,13 @@ void Deoptimizer::GenerateDeoptimizationEntries(MacroAssembler* masm,
       __ StoreP(ToRegister(i), MemOperand(sp, kPointerSize * i));
     }
   }
-
-  __ mov(ip, Operand(ExternalReference::Create(
-                 IsolateAddressId::kCEntryFPAddress, isolate)));
-  __ StoreP(fp, MemOperand(ip));
-
+  {
+    UseScratchRegisterScope temps(masm);
+    Register scratch = temps.Acquire();
+    __ mov(scratch, Operand(ExternalReference::Create(
+                        IsolateAddressId::kCEntryFPAddress, isolate)));
+    __ StoreP(fp, MemOperand(scratch));
+  }
   const int kSavedRegistersAreaSize =
       (kNumberOfRegisters * kPointerSize) + kDoubleRegsSize + kFloatRegsSize;
 
@@ -210,19 +212,27 @@ void Deoptimizer::GenerateDeoptimizationEntries(MacroAssembler* masm,
   __ push(r9);
 
   // Restore the registers from the last output frame.
-  DCHECK(!(ip.bit() & restored_regs));
-  __ mr(ip, r5);
-  for (int i = kNumberOfRegisters - 1; i >= 0; i--) {
-    int offset = (i * kPointerSize) + FrameDescription::registers_offset();
-    if ((restored_regs & (1 << i)) != 0) {
-      __ LoadP(ToRegister(i), MemOperand(ip, offset));
+  {
+    UseScratchRegisterScope temps(masm);
+    Register scratch = temps.Acquire();
+    DCHECK(!(scratch.bit() & restored_regs));
+    __ mr(scratch, r5);
+    for (int i = kNumberOfRegisters - 1; i >= 0; i--) {
+      int offset = (i * kPointerSize) + FrameDescription::registers_offset();
+      if ((restored_regs & (1 << i)) != 0) {
+        __ LoadP(ToRegister(i), MemOperand(scratch, offset));
+      }
     }
   }
 
-  __ pop(ip);  // get continuation, leave pc on stack
-  __ pop(r0);
-  __ mtlr(r0);
-  __ Jump(ip);
+  {
+    UseScratchRegisterScope temps(masm);
+    Register scratch = temps.Acquire();
+    __ pop(scratch);  // get continuation, leave pc on stack
+    __ pop(r0);
+    __ mtlr(r0);
+    __ Jump(scratch);
+  }
   __ stop();
 }