2 files changed, 12 insertions, 4 deletions
diff --git a/lib/System/Unix/Memory.inc b/lib/System/Unix/Memory.inc
index a89fd22..4475960 100644
--- a/lib/System/Unix/Memory.inc
+++ b/lib/System/Unix/Memory.inc
@@ -25,7 +25,7 @@ namespace llvm {
 /// to emit code to the memory then jump to it.  Getting this type of memory
 /// is very OS specific.
 ///
-MemoryBlock Memory::AllocateRWX(unsigned NumBytes) {
+MemoryBlock Memory::AllocateRWX(unsigned NumBytes, const MemoryBlock* NearBlock) {
   if (NumBytes == 0) return MemoryBlock();
 
   long pageSize = Process::GetPageSize();
@@ -47,10 +47,16 @@ MemoryBlock Memory::AllocateRWX(unsigned NumBytes) {
   MAP_ANON
 #endif
   ;
-  void *pa = ::mmap(0, pageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC,
+
+  void* start = NearBlock ? (unsigned char*) NearBlock->base() + NearBlock->size() : 0;
+
+  void *pa = ::mmap(start, pageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC,
                     flags, fd, 0);
   if (pa == MAP_FAILED) {
-    ThrowErrno("Can't allocate RWX Memory");
+    if (NearBlock) //Try again without a near hint
+      return AllocateRWX(NumBytes, 0);
+    else
+      ThrowErrno("Can't allocate RWX Memory");
   }
   MemoryBlock result;
   result.Address = pa;
diff --git a/lib/System/Win32/Memory.inc b/lib/System/Win32/Memory.inc
index 9ebef6a..7e93dee 100644
--- a/lib/System/Win32/Memory.inc
+++ b/lib/System/Win32/Memory.inc
@@ -23,12 +23,14 @@ using namespace sys;
 //===          and must not be UNIX code
 //===----------------------------------------------------------------------===//
 
-MemoryBlock Memory::AllocateRWX(unsigned NumBytes) {
+MemoryBlock Memory::AllocateRWX(unsigned NumBytes, const MemoryBlock* NearBlock) {
   if (NumBytes == 0) return MemoryBlock();
 
   static const long pageSize = Process::GetPageSize();
   unsigned NumPages = (NumBytes+pageSize-1)/pageSize;
 
+  //FIXME: support NearBlock if ever needed on Win64.
+
   void *pa = VirtualAlloc(NULL, NumPages*pageSize, MEM_COMMIT,
                   PAGE_EXECUTE_READWRITE);
   if (pa == NULL) {