Add CODE_POINTER_ALIGN, use it in Page to align generated code.

src/globals.h

Index: src/globals.h
diff --git a/src/globals.h b/src/globals.h
index f168d6eb14ebef213928a5145017bc3196b42d1e..ff712f9e6a3c5d0d2f0f32111b0eb074446d232f 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -214,6 +214,12 @@ const intptr_t kMapAlignmentBits = kObjectAlignmentBits + 3;
 const intptr_t kMapAlignment = (1 << kMapAlignmentBits);
 const intptr_t kMapAlignmentMask = kMapAlignment - 1;
 
+// Desired alignment for generated code.
+// Code entry points are aligned to 32 bytes (cache line size in some CPUs).

[Vitaly Repeshko, 2010/09/24 15:45:38]

In most of the CPUs we deal with it's actually 64. Please change the
parenthetical remark to "to improve cache line utilization".

+const int kCodeAlignmentBits = 5;
+const intptr_t kCodeAlignment = 1 << kCodeAlignmentBits;
+const intptr_t kCodeAlignmentMask = kCodeAlignment - 1;
+
 // Tag information for Failure.
 const int kFailureTag = 3;
 const int kFailureTagSize = 2;
@@ -588,6 +594,10 @@ enum StateTag {
 #define MAP_POINTER_ALIGN(value)                                \
   (((value) + kMapAlignmentMask) & ~kMapAlignmentMask)
 
+// CODE_POINTER_ALIGN returns the value aligned as a generated code segment.
+#define CODE_POINTER_ALIGN(value)                               \
+  (((value) + kCodeAlignmentMask) & ~kCodeAlignmentMask)
+
 // The expression OFFSET_OF(type, field) computes the byte-offset
 // of the specified field relative to the containing type. This
 // corresponds to 'offsetof' (in stddef.h), except that it doesn't