Add an AllocateRW to match AllocateRWX.

llvm-svn: 48676

1 files changed, 47 insertions, 0 deletions

diff --git a/llvm/lib/System/Unix/Memory.inc b/llvm/lib/System/Unix/Memory.inc
index afa8f03117f..164988793f7 100644
--- a/llvm/lib/System/Unix/Memory.inc
+++ b/llvm/lib/System/Unix/Memory.inc
@@ -67,6 +67,53 @@ llvm::sys::Memory::AllocateRWX(unsigned NumBytes, const MemoryBlock* NearBlock,
   return result;
 }
 
+/// AllocateRWMemory - Allocate a slab of memory with read/write permissions. 
+/// This memory needs to have executable permissions set before it can be used
+/// to execute JIT'ed code.
+llvm::sys::MemoryBlock 
+llvm::sys::Memory::AllocateRW(unsigned NumBytes, const MemoryBlock* NearBlock,
+                               std::string *ErrMsg) {
+  if (NumBytes == 0) return MemoryBlock();
+
+  long pageSize = Process::GetPageSize();
+  unsigned NumPages = (NumBytes+pageSize-1)/pageSize;
+
+  int fd = -1;
+#ifdef NEED_DEV_ZERO_FOR_MMAP
+  static int zero_fd = open("/dev/zero", O_RDWR);
+  if (zero_fd == -1) {
+    MakeErrMsg(ErrMsg, "Can't open /dev/zero device");
+    return MemoryBlock();
+  }
+  fd = zero_fd;
+#endif
+
+  int flags = MAP_PRIVATE |
+#ifdef HAVE_MMAP_ANONYMOUS
+  MAP_ANONYMOUS
+#else
+  MAP_ANON
+#endif
+  ;
+
+  void* start = NearBlock ? (unsigned char*)NearBlock->base() + 
+                            NearBlock->size() : 0;
+
+  void *pa = ::mmap(start, pageSize*NumPages, PROT_READ|PROT_WRITE,
+                    flags, fd, 0);
+  if (pa == MAP_FAILED) {
+    if (NearBlock) //Try again without a near hint
+      return AllocateRWX(NumBytes, 0);
+
+    MakeErrMsg(ErrMsg, "Can't allocate RWX Memory");
+    return MemoryBlock();
+  }
+  MemoryBlock result;
+  result.Address = pa;
+  result.Size = NumPages*pageSize;
+  return result;
+}
+
 bool llvm::sys::Memory::ReleaseRWX(MemoryBlock &M, std::string *ErrMsg) {
   if (M.Address == 0 || M.Size == 0) return false;
   if (0 != ::munmap(M.Address, M.Size))