re PR rtl-optimization/6627 (-fno-align-functions regression from 2.95)

	PR optimization/6627
	* toplev.c (force_align_functions_log): New global variable.
	* flags.h (force_align_functions_log): Add extern prototype.
	* varasm.c (assemble_start_function): Use it to force minimum
	function alignment.
	* config/i386/i386.h (FUNCTION_BOUNDARY): Set the correct
	minimum function alignment to one byte.
	(TARGET_PTRMEMFUNC_VBIT_LOCATION): Store the virtual bit in
	the least significant bit of vtable member function pointers.
	* tree.h (enum ptrmemfunc_vbit_where_t): Move definition to
	here from cp/cp-tree.h.

	* cp/cp-tree.h (enum ptrmemfunc_vbit_where_t): Delete definition
	from here, and move it to tree.h.
	* cp/decl.c (cxx_init_decl_processing): If storing the vbit
	in function pointers, ensure that force_align_functions_log
	is atleast one.

	* java/lang.c (java_init): If storing the vbit in function
	pointers, ensure that force_align_functions_log is atleast
	one to aid compatability with g++ vtables.

From-SVN: r57745

1 files changed, 27 insertions, 0 deletions

diff --git a/gcc/tree.h b/gcc/tree.h
index 1d0941c..252c2bc 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -2114,6 +2114,33 @@ enum tls_model {
 
 extern enum tls_model flag_tls_default;
 
+/* A pointer-to-function member type looks like:
+
+     struct {
+       __P __pfn;
+       ptrdiff_t __delta;
+     };
+
+   If __pfn is NULL, it is a NULL pointer-to-member-function.
+
+   (Because the vtable is always the first thing in the object, we
+   don't need its offset.)  If the function is virtual, then PFN is
+   one plus twice the index into the vtable; otherwise, it is just a
+   pointer to the function.
+
+   Unfortunately, using the lowest bit of PFN doesn't work in
+   architectures that don't impose alignment requirements on function
+   addresses, or that use the lowest bit to tell one ISA from another,
+   for example.  For such architectures, we use the lowest bit of
+   DELTA instead of the lowest bit of the PFN, and DELTA will be
+   multiplied by 2.  */
+
+enum ptrmemfunc_vbit_where_t
+{
+  ptrmemfunc_vbit_in_pfn,
+  ptrmemfunc_vbit_in_delta
+};
+
 #define NULL_TREE (tree) NULL
 
 /* Approximate positive square root of a host double.  This is for