Re: [PATCH ARM]: PR67745: Fix function alignment after __attribute__ 2/2

[Christian Bruel <christian.bruel@st.com>]

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The ARM target can switch different alignment requirements between the 
thumb or arm, thanks to the attribute ((target)). Using 
FUNCTION_BOUNDARY that now depends on the switchable target_flag.

The previous attempt to fix this was to use the set_current_function 
hook to reset DECL_ALIGN. On a second thought I found this not 
satisfactory because this hook is called multiple time between passes, 
whereas the setting only needs to be done once.

Instead, this patch resets the function's DECL_ALIGN in 
allocate_struct_function, when not enforced by the user or the language, 
after the attributes are processed.

Tested for arm-none-eabi (with the 1/2 part 
https://gcc.gnu.org/ml/gcc-patches/2015-09/msg02198.html)

Bootstraped for x86_64-unknown-linux-gnu and tested (c+,c++,fortran)

Comments ? OK for trunk ?

thanks

Christian



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2015-10-07  Christian Bruel  <christian.bruel@st.com>

	PR target/67745
	* function.c (allocate_struct_function): Relayout function's alignment.

Index: gcc/function.c
===================================================================
--- gcc/function.c	(revision 228515)
+++ gcc/function.c	(working copy)
@@ -4840,6 +4840,12 @@ allocate_struct_function (tree fndecl, b
 	  for (tree parm = DECL_ARGUMENTS (fndecl); parm;
 	       parm = DECL_CHAIN (parm))
 	    relayout_decl (parm);
+
+	  /* Similarly, relayout function's alignment if not forced.  */
+	  if (!DECL_USER_ALIGN (fndecl)
+	      && (TREE_CODE (fntype) != METHOD_TYPE
+		  || TARGET_PTRMEMFUNC_VBIT_LOCATION != ptrmemfunc_vbit_in_pfn))
+	    DECL_ALIGN (fndecl) = FUNCTION_BOUNDARY;
 	}
 
       if (!abstract_p && aggregate_value_p (result, fndecl))