3 files changed, 22 insertions, 7 deletions

diff --git a/compiler/llvmGen/Llvm/AbsSyn.hs b/compiler/llvmGen/Llvm/AbsSyn.hs
index f92bd89c5c..24d0856ea3 100644
--- a/compiler/llvmGen/Llvm/AbsSyn.hs
+++ b/compiler/llvmGen/Llvm/AbsSyn.hs
@@ -65,6 +65,8 @@ data LlvmFunction = LlvmFunction {
 
 type LlvmFunctions = [LlvmFunction]
 
+type SingleThreaded = Bool
+
 -- | LLVM ordering types for synchronization purposes. (Introduced in LLVM
 -- 3.0). Please see the LLVM documentation for a better description.
 data LlvmSyncOrdering
@@ -224,6 +226,11 @@ data LlvmExpression
   | Load LlvmVar
 
   {- |
+    Atomic load of the value at location ptr
+  -}
+  | ALoad LlvmSyncOrdering SingleThreaded LlvmVar
+
+  {- |
     Navigate in an structure, selecting elements
       * inbound: Is the pointer inbounds? (computed pointer doesn't overflow)
       * ptr:     Location of the structure
diff --git a/compiler/llvmGen/Llvm/PpLlvm.hs b/compiler/llvmGen/Llvm/PpLlvm.hs
index b8343ceff3..73077257f8 100644
--- a/compiler/llvmGen/Llvm/PpLlvm.hs
+++ b/compiler/llvmGen/Llvm/PpLlvm.hs
@@ -1,3 +1,5 @@
+{-# LANGUAGE CPP #-}
+
 --------------------------------------------------------------------------------
 -- | Pretty print LLVM IR Code.
 --
@@ -237,6 +239,7 @@ ppLlvmExpression expr
         Insert     vec elt idx      -> ppInsert vec elt idx
         GetElemPtr inb ptr indexes  -> ppGetElementPtr inb ptr indexes
         Load       ptr              -> ppLoad ptr
+        ALoad      ord st ptr       -> ppALoad ord st ptr
         Malloc     tp amount        -> ppMalloc tp amount
         Phi        tp precessors    -> ppPhi tp precessors
         Asm        asm c ty v se sk -> ppAsm asm c ty v se sk
@@ -325,13 +328,18 @@ ppSyncOrdering SyncSeqCst    = text "seq_cst"
 -- of specifying alignment.
 
 ppLoad :: LlvmVar -> SDoc
-ppLoad var
-    | isVecPtrVar var = text "load" <+> ppr var <>
-                        comma <+> text "align 1"
-    | otherwise       = text "load" <+> ppr var
+ppLoad var = text "load" <+> ppr var <> align
   where
-    isVecPtrVar :: LlvmVar -> Bool
-    isVecPtrVar = isVector . pLower . getVarType
+    align | isVector . pLower . getVarType $ var = text ", align 1"
+          | otherwise = empty
+
+ppALoad :: LlvmSyncOrdering -> SingleThreaded -> LlvmVar -> SDoc
+ppALoad ord st var = sdocWithDynFlags $ \dflags ->
+  let alignment = (llvmWidthInBits dflags $ getVarType var) `quot` 8
+      align     = text ", align" <+> ppr alignment
+      sThreaded | st        = text " singlethread"
+                | otherwise = empty
+  in text "load atomic" <+> ppr var <> sThreaded <+> ppSyncOrdering ord <> align
 
 ppStore :: LlvmVar -> LlvmVar -> SDoc
 ppStore val dst
diff --git a/compiler/llvmGen/Llvm/Types.hs b/compiler/llvmGen/Llvm/Types.hs
index 6b9c8c181a..89b0e4e141 100644
--- a/compiler/llvmGen/Llvm/Types.hs
+++ b/compiler/llvmGen/Llvm/Types.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE CPP, GeneralizedNewtypeDeriving #-}
 
 --------------------------------------------------------------------------------
 -- | The LLVM Type System.