ARM, ARM64: Optimize array copy

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 249c22f77bf3176b3e23583f3c29f1c02c274681..48c26526c0b9659d2c63880bea1051bf264dceea 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -4344,6 +4344,125 @@ void LCodeGen::DoStoreKeyedFixedArray(LStoreKeyed* instr) {
 }
 
 
+void LCodeGen::DoFillElements(LFillElements* instr) {
+  Label end;
+  Register elements = ToRegister(instr->elements());
+  Register dst = scratch0();
+  ASSERT(instr->hydrogen()->to()->representation().IsInteger32());
+  ASSERT(instr->hydrogen()->from()->representation().IsInteger32());
+  int shift_size =
+      instr->value()->IsDoubleRegister() ? kDoubleSizeLog2 : kPointerSizeLog2;
+  // We will be able to skip the first test (which checks that we have at
+  // least one value to fill) if we know the number of values to copy.
+  bool skip_first_test = false;
+  Register remain;
+  if (instr->from()->IsConstantOperand()) {
+    int from = ToInteger32(LConstantOperand::cast(instr->from()));
+    int start_offset =
+        FixedDoubleArray::kHeaderSize - kHeapObjectTag + (from << shift_size);
+    if (instr->to()->IsConstantOperand()) {
+      int to = ToInteger32(LConstantOperand::cast(instr->to()));
+      if (instr->scratch() == NULL) {
+        // Scratch is null, if to - from was small enough to unroll the loop.
+        int max = to - from;
+        if (instr->value()->IsDoubleRegister()) {
+          __ add(dst, elements, Operand(start_offset));
+          DoubleRegister value = ToDoubleRegister(instr->value());
+          for (int count = 0; count < max; count++) {
+            __ vstr(value, dst, count * kDoubleSize);
+          }
+        } else {
+          Register value = ToRegister(instr->value());
+          for (int count = 0; count < max; count++) {
+            __ str(value,
+                   MemOperand(elements, start_offset + count * kPointerSize));
+          }
+        }
+        __ bind(&end);
+        return;
+      }
+      __ add(dst, elements, Operand(start_offset));
+      skip_first_test = true;
+      remain = ToRegister(instr->scratch());
+      __ mov(remain, Operand(to - from));
+    } else {
+      remain = ToRegister(instr->scratch());
+      Register to = ToRegister(instr->to());
+      if (from == 0) {
+        __ mov(remain, Operand(to), SetCC);
+      } else {
+        __ sub(remain, to, Operand(from), SetCC);
+      }
+      __ add(dst, elements, Operand(start_offset));
+    }
+  } else {
+    remain = ToRegister(instr->scratch());
+    Register from = ToRegister(instr->from());
+    if (instr->to()->IsConstantOperand()) {
+      int to = ToInteger32(LConstantOperand::cast(instr->to()));
+      __ rsb(remain, from, Operand(to), SetCC);
+    } else {
+      Register to = ToRegister(instr->to());
+      __ sub(remain, to, Operand(from), SetCC);
+    }
+    __ add(dst, elements,
+           Operand(FixedDoubleArray::kHeaderSize - kHeapObjectTag));
+    __ add(dst, dst, Operand(from, LSL, shift_size));
+  }
+  Label loop, done;
+  if (!skip_first_test) {
+    __ b(le, &done);
+  }
+  __ bind(&loop);
+  __ sub(remain, remain, Operand(1), SetCC);
+  if (instr->value()->IsDoubleRegister()) {
+    DoubleRegister value = ToDoubleRegister(instr->value());
+    __ vstr(value, dst, 0);
+    __ add(dst, dst, Operand(kDoubleSize));
+  } else {
+    Register value = ToRegister(instr->value());
+    __ str(value, MemOperand(dst, kPointerSize, PostIndex));
+  }
+  __ b(gt, &loop);
+  if (!skip_first_test) {
+    __ bind(&done);
+  }
+  __ bind(&end);
+}
+
+
+void LCodeGen::DoCopyElements(LCopyElements* instr) {
+  Label loop, done;
+  Register dst = ToRegister(instr->dst());
+  Register src = ToRegister(instr->src());
+  Register length = ToRegister(instr->length());
+  __ cmp(length, Operand::Zero());
+  __ add(src, src, Operand(FixedDoubleArray::kHeaderSize - kHeapObjectTag));
+  __ add(dst, dst,
+         Operand(FixedDoubleArray::kHeaderSize - kHeapObjectTag));
+  __ b(eq, &done);
+  __ bind(&loop);
+  if (instr->hydrogen()->length()->representation().IsSmi()) {
+    __ sub(length, length, Operand(Smi::FromInt(1)), SetCC);
+  } else {
+    __ sub(length, length, Operand(1), SetCC);
+  }
+  if (IsFastSmiOrObjectElementsKind(instr->elements_kind())) {
+    Register value = scratch0();
+    __ ldr(value, MemOperand(src, kPointerSize, PostIndex));
+    __ str(value, MemOperand(dst, kPointerSize, PostIndex));
+  } else {
+    DoubleRegister value = double_scratch0();
+    __ vldr(value, src, 0);
+    __ vstr(value, dst, 0);
+    __ add(src, src, Operand(kDoubleSize));
+    __ add(dst, dst, Operand(kDoubleSize));
+  }
+  __ b(gt, &loop);
+  __ bind(&done);
+}
+
+
 void LCodeGen::DoStoreKeyed(LStoreKeyed* instr) {
   // By cases: external, fast double
   if (instr->is_typed_elements()) {