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Date: Fri, 12 Oct 2012 14:06:14 +0000
Subject: [v8] r12718 committed - Use immediate add when possible in space allocator...
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Revision: 12718
Author:   da...@chromium.org
Date:     Fri Oct 12 07:06:03 2012
Log:      Use immediate add when possible in space allocator

Save one instruction in allocating new space by using an immediate add if
possible to calculate the new top of heap.

BUG=

Review URL: https://chromiumcodereview.appspot.com/11091068
Patch from Anthony Berent <aber...@chromium.org>.
http://code.google.com/p/v8/source/detail?r=12718

Modified:
  /branches/bleeding_edge/src/arm/macro-assembler-arm.cc

=======================================
--- /branches/bleeding_edge/src/arm/macro-assembler-arm.cc	Fri Oct 12  
04:09:14 2012
+++ /branches/bleeding_edge/src/arm/macro-assembler-arm.cc	Fri Oct 12  
07:06:03 2012
@@ -1570,7 +1570,11 @@
    Register topaddr = scratch1;
    Register obj_size_reg = scratch2;
    mov(topaddr, Operand(new_space_allocation_top));
-  mov(obj_size_reg, Operand(object_size));
+  Operand obj_size_operand = Operand(object_size);
+  if (!obj_size_operand.is_single_instruction(this)) {
+    // We are about to steal IP, so we need to load this value first
+    mov(obj_size_reg, obj_size_operand);
+  }

    // This code stores a temporary value in ip. This is OK, as the code  
below
    // does not need ip for implicit literal generation.
@@ -1592,7 +1596,13 @@

    // Calculate new top and bail out if new space is exhausted. Use result
    // to calculate the new top.
-  add(scratch2, result, Operand(obj_size_reg), SetCC);
+  if (obj_size_operand.is_single_instruction(this)) {
+    // We can add the size as an immediate
+    add(scratch2, result, obj_size_operand, SetCC);
+  } else {
+    // Doesn't fit in an immediate, we have to use the register
+    add(scratch2, result, obj_size_reg, SetCC);
+  }
    b(cs, gc_required);
    cmp(scratch2, Operand(ip));
    b(hi, gc_required);