Optimize fast element conversion in arm using batch store/loads.

src/arm/macro-assembler-arm.h

Index: src/arm/macro-assembler-arm.h
diff --git a/src/arm/macro-assembler-arm.h b/src/arm/macro-assembler-arm.h
index 2222baaf975ea97ff2d93a2e69815fa572707724..90c4b375491c175f821966677a42ae2d08e32727 100644
--- a/src/arm/macro-assembler-arm.h
+++ b/src/arm/macro-assembler-arm.h
@@ -320,8 +320,11 @@ class MacroAssembler: public Assembler {
   }
 
   // Push four registers.  Pushes leftmost register first (to highest address).
-  void Push(Register src1, Register src2,
-            Register src3, Register src4, Condition cond = al) {
+  void Push(Register src1,
+            Register src2,
+            Register src3,
+            Register src4,
+            Condition cond = al) {
     ASSERT(!src1.is(src2));
     ASSERT(!src2.is(src3));
     ASSERT(!src1.is(src3));
@@ -360,6 +363,57 @@ class MacroAssembler: public Assembler {
     }
   }
 

[Yang, 2011/10/19 11:41:11]

Not moving the function body to macro-assembler-arm.cc because ldm is not
defined there.

+  // Pop three registers.  Pops rightmost register first (from lower address).
+  void Pop(Register src1, Register src2, Register src3, Condition cond = al) {
+    ASSERT(!src1.is(src2));
+    ASSERT(!src2.is(src3));
+    ASSERT(!src1.is(src3));
+    if (src1.code() > src2.code()) {
+      if (src2.code() > src3.code()) {
+        ldm(ia_w, sp, src1.bit() | src2.bit() | src3.bit(), cond);
+      } else {
+        ldr(src3, MemOperand(sp, 4, PostIndex), cond);
+        ldm(ia_w, sp, src1.bit() | src2.bit(), cond);
+      }
+    } else {
+      Pop(src2, src3, cond);
+      str(src1, MemOperand(sp, 4, PostIndex), cond);
+    }
+  }
+
+  // Pop four registers.  Pops rightmost register first (from lower address).
+  void Pop(Register src1,
+           Register src2,
+           Register src3,
+           Register src4,
+           Condition cond = al) {
+    ASSERT(!src1.is(src2));
+    ASSERT(!src2.is(src3));
+    ASSERT(!src1.is(src3));
+    ASSERT(!src1.is(src4));
+    ASSERT(!src2.is(src4));
+    ASSERT(!src3.is(src4));
+    if (src1.code() > src2.code()) {
+      if (src2.code() > src3.code()) {
+        if (src3.code() > src4.code()) {
+          ldm(ia_w,
+              sp,
+              src1.bit() | src2.bit() | src3.bit() | src4.bit(),
+              cond);
+        } else {
+          ldr(src4, MemOperand(sp, 4, PostIndex), cond);
+          ldm(ia_w, sp, src1.bit() | src2.bit() | src3.bit(), cond);
+        }
+      } else {
+        Pop(src3, src4, cond);
+        ldm(ia_w, sp, src1.bit() | src2.bit(), cond);
+      }
+    } else {
+      Pop(src2, src3, src4, cond);
+      ldr(src1, MemOperand(sp, 4, PostIndex), cond);
+    }
+  }
+
   // Push and pop the registers that can hold pointers, as defined by the
   // RegList constant kSafepointSavedRegisters.
   void PushSafepointRegisters();