Runtime linker: Break m32 allocator out into its own file

This makes the code a little more modular and allows the removal of some
CPP hackery. By providing dummy implementations of of the `m32_*`
functions (which simply call `errorBelch`) it means that the call sites
for these functions are syntax checked even when `RTS_LINKER_USE_MMAP`
is `0`.

Also changes some size parameter types from `unsigned int` to `size_t`.

Test Plan: Validate on Linux, OS X and Windows

Reviewers: Phyx, hsyl20, bgamari, simonmar, austin

Reviewed By: simonmar, austin

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2237

1 files changed, 16 insertions, 1 deletions

diff --git a/rts/sm/OSMem.h b/rts/sm/OSMem.h
index a9d4fc9cd2..8518f05d1b 100644
--- a/rts/sm/OSMem.h
+++ b/rts/sm/OSMem.h
@@ -16,10 +16,25 @@ void *osGetMBlocks(uint32_t n);
 void osFreeMBlocks(void *addr, uint32_t n);
 void osReleaseFreeMemory(void);
 void osFreeAllMBlocks(void);
-W_ getPageSize (void);
+size_t getPageSize (void);
 StgWord64 getPhysicalMemorySize (void);
 void setExecutable (void *p, W_ len, rtsBool exec);
 
+INLINE_HEADER size_t
+roundDownToPage (size_t x)
+{
+    size_t size = getPageSize();
+    return (x & ~(size - 1));
+}
+
+INLINE_HEADER size_t
+roundUpToPage (size_t x)
+{
+    size_t size = getPageSize();
+    return ((x + size - 1) & ~(size - 1));
+}
+
+
 #ifdef USE_LARGE_ADDRESS_SPACE
 
 /*