on ARMv7 with VFPv3[D16] support pass appropriate -mattr value to LLVM llc

compiler/main/DriverPipeline.hs

@@ -1333,7 +1333,8 @@ runPhase LlvmLlc input_fn dflags
                     SysTools.Option $ "-relocation-model=" ++ rmodel,
                     SysTools.FileOption "" input_fn,
                     SysTools.Option "-o", SysTools.FileOption "" output_fn]
-                ++ map SysTools.Option lc_opts)
+                ++ map SysTools.Option lc_opts
+                ++ map SysTools.Option fpOpts)
 
     return (LlvmMangle, output_fn)
   where
@@ -1341,6 +1342,17 @@ runPhase LlvmLlc input_fn dflags
         llvmOpts = if platformOS (targetPlatform dflags) == OSDarwin
                    then ["-O1", "-O2", "-O2"]
                    else ["-O1", "-O2", "-O3"]
+        -- On ARMv7 using LLVM, LLVM fails to allocate floating point registers
+        -- while compiling GHC source code. It's probably due to fact
+        -- that it does not enable VFP by default. Let's do this manually
+        -- here
+        fpOpts = case platformArch (targetPlatform dflags) of 
+                   ArchARM ARMv7 ext -> if (elem VFPv3 ext)
+                                      then ["-mattr=+v7,+vfp3"]
+                                      else if (elem VFPv3D16 ext)
+                                           then ["-mattr=+v7,+vfp3,+d16"]
+                                           else []
+                   _               -> []
 
 -----------------------------------------------------------------------------
 -- LlvmMangle phase
@@ -1465,8 +1477,8 @@ mkExtraObjToLinkIntoBinary dflags dep_packages = do
 
             elfSectionNote :: String
             elfSectionNote = case platformArch (targetPlatform dflags) of
-                               ArchARM    -> "%note"
-                               _          -> "@note"
+                               ArchARM _ _ -> "%note"
+                               _           -> "@note"
 
 -- The "link info" is a string representing the parameters of the
 -- link.  We save this information in the binary, and the next time we