Subzero: Use CFG-local arena allocation for relevant containers.

src/assembler.h

Index: src/assembler.h
diff --git a/src/assembler.h b/src/assembler.h
index dc706683ea676cc8c21445ab753c5f700c03e2b0..cdbc50553a0a2bf4ea454537ff64fd82172f6cb2 100644
--- a/src/assembler.h
+++ b/src/assembler.h
@@ -24,9 +24,7 @@
 #define SUBZERO_SRC_ASSEMBLER_H
 
 #include "IceDefs.h"
-
 #include "IceFixups.h"
-#include "llvm/Support/Allocator.h"
 
 namespace Ice {
 
@@ -232,7 +230,7 @@ public:
   void emitIASBytes(GlobalContext *Ctx) const;
 
 private:
-  llvm::BumpPtrAllocator Allocator;
+  ArenaAllocator Allocator;

[jvoung (off chromium), 2014/12/18 18:39:59]

I wonder if the assembler should just use the CFG allocator. Its allocation
should happen after the other CFG allocations. There are tiny relocation
objects, and label objects that get allocated. Then there is the contiguous
AssemblerBuffer chunks that represent the function's .text section, that get
allocated/grow.


Anyway, that can be tuned later.

[Jim Stichnoth, 2014/12/18 23:39:56]

I think the assembler should use its own allocator for the machine code bytes
and the fixups.  This is because we probably want a separate thread to serialize
the assembly across all functions into the ELF file.  The translator threads
would add the assembly buffers to a work queue, destroy the Cfg, and grab a new
function to translate.

I added a new ALLOCATION.rst file to try to document these assumptions.

 
 protected:
   AssemblerBuffer buffer_;