Add flag to set minimum semi-space size.

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/279513003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21220 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/flag-definitions.h

@@ -463,6 +463,9 @@ DEFINE_bool(always_inline_smi_code, false,
             "always inline smi code in non-opt code")
 
 // heap.cc
+DEFINE_int(min_semi_space_size, 0,
+    "min size of a semi-space (in MBytes), the new space consists of two"
+    "semi-spaces")
 DEFINE_int(max_semi_space_size, 0,
     "max size of a semi-space (in MBytes), the new space consists of two"
     "semi-spaces")

src/heap.cc

@@ -5018,7 +5018,7 @@ bool Heap::ConfigureHeap(int max_semi_space_size,
     if (max_semi_space_size_ > reserved_semispace_size_) {
       max_semi_space_size_ = reserved_semispace_size_;
       if (FLAG_trace_gc) {
-        PrintPID("Max semispace size cannot be more than %dkbytes\n",
+        PrintPID("Max semi-space size cannot be more than %d kbytes\n",
                  reserved_semispace_size_ >> 10);
       }
     }
@@ -5038,6 +5038,20 @@ bool Heap::ConfigureHeap(int max_semi_space_size,
   // for containment.
   max_semi_space_size_ = RoundUpToPowerOf2(max_semi_space_size_);
   reserved_semispace_size_ = RoundUpToPowerOf2(reserved_semispace_size_);
+
+  if (FLAG_min_semi_space_size > 0) {
+    int initial_semispace_size = FLAG_min_semi_space_size * MB;
+    if (initial_semispace_size > max_semi_space_size_) {
+      initial_semispace_size_ = max_semi_space_size_;
+      if (FLAG_trace_gc) {
+        PrintPID("Min semi-space size cannot be more than the maximum"
+                 "semi-space size of %d MB\n", max_semi_space_size_);
+      }
+    } else {
+      initial_semispace_size_ = initial_semispace_size;
+    }
+  }
+
   initial_semispace_size_ = Min(initial_semispace_size_, max_semi_space_size_);
 
   // The external allocation limit should be below 256 MB on all architectures