Add target hook to override DWARF2 frame register size

gcc/

	* target.def (TARGET_DWARF_FRAME_REG_MODE): New target hook.
	* targhooks.c (default_dwarf_frame_reg_mode): New function.
	* targhooks.h (default_dwarf_frame_reg_mode): New prototype.
	* doc/tm.texi.in (TARGET_DWARF_FRAME_REG_MODE): Document.
	* doc/tm.texi: Regenerate.
	* dwarf2cfi.c (expand_builtin_init_dwarf_reg_sizes): Abstract mode
	selection logic to default_dwarf_frame_reg_mode.

From-SVN: r214898

7 files changed, 45 insertions, 3 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9ae222b..94cf799 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2014-09-03  Matthew Fortune  <matthew.fortune@imgtec.com>
+
+	* target.def (TARGET_DWARF_FRAME_REG_MODE): New target hook.
+	* targhooks.c (default_dwarf_frame_reg_mode): New function.
+	* targhooks.h (default_dwarf_frame_reg_mode): New prototype.
+	* doc/tm.texi.in (TARGET_DWARF_FRAME_REG_MODE): Document.
+	* doc/tm.texi: Regenerate.
+	* dwarf2cfi.c (expand_builtin_init_dwarf_reg_sizes): Abstract mode
+	selection logic to default_dwarf_frame_reg_mode.
+
 2014-09-03  Marek Polacek  <polacek@redhat.com>
 
 	* doc/invoke.texi: Document that -Wlogical-not-parentheses is enabled
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 0c44d51..9496477 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -8871,6 +8871,13 @@ register in Dwarf.  Otherwise, this hook should return @code{NULL_RTX}.
 If not defined, the default is to return @code{NULL_RTX}.
 @end deftypefn
 
+@deftypefn {Target Hook} {enum machine_mode} TARGET_DWARF_FRAME_REG_MODE (int @var{regno})
+Given a register, this hook should return the mode which the
+corresponding Dwarf frame register should have.  This is normally
+used to return a smaller mode than the raw mode to prevent call
+clobbered parts of a register altering the frame register size
+@end deftypefn
+
 @deftypefn {Target Hook} void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree @var{address})
 If some registers are represented in Dwarf-2 unwind information in
 multiple pieces, define this hook to fill in information about the
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 7a63353..152d37d 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -6594,6 +6594,8 @@ the target supports DWARF 2 frame unwind information.
 
 @hook TARGET_DWARF_REGISTER_SPAN
 
+@hook TARGET_DWARF_FRAME_REG_MODE
+
 @hook TARGET_INIT_DWARF_REG_SIZES_EXTRA
 
 @hook TARGET_ASM_TTYPE
diff --git a/gcc/dwarf2cfi.c b/gcc/dwarf2cfi.c
index f30274e..b1659dd 100644
--- a/gcc/dwarf2cfi.c
+++ b/gcc/dwarf2cfi.c
@@ -271,11 +271,9 @@ expand_builtin_init_dwarf_reg_sizes (tree address)
       if (rnum < DWARF_FRAME_REGISTERS)
 	{
 	  HOST_WIDE_INT offset = rnum * GET_MODE_SIZE (mode);
-	  enum machine_mode save_mode = reg_raw_mode[i];
 	  HOST_WIDE_INT size;
+	  enum machine_mode save_mode = targetm.dwarf_frame_reg_mode (i);
 
-	  if (HARD_REGNO_CALL_PART_CLOBBERED (i, save_mode))
-	    save_mode = choose_hard_reg_mode (i, 1, true);
 	  if (dnum == DWARF_FRAME_RETURN_COLUMN)
 	    {
 	      if (save_mode == VOIDmode)
diff --git a/gcc/target.def b/gcc/target.def
index e7212ea..29285f2 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -3218,6 +3218,17 @@ If not defined, the default is to return @code{NULL_RTX}.",
  rtx, (rtx reg),
  hook_rtx_rtx_null)
 
+/* Given a register return the mode of the corresponding DWARF frame
+   register.  */
+DEFHOOK
+(dwarf_frame_reg_mode,
+ "Given a register, this hook should return the mode which the\n\
+corresponding Dwarf frame register should have.  This is normally\n\
+used to return a smaller mode than the raw mode to prevent call\n\
+clobbered parts of a register altering the frame register size",
+ enum machine_mode, (int regno),
+ default_dwarf_frame_reg_mode)
+
 /* If expand_builtin_init_dwarf_reg_sizes needs to fill in table
    entries not corresponding directly to registers below
    FIRST_PSEUDO_REGISTER, this hook should generate the necessary
diff --git a/gcc/targhooks.c b/gcc/targhooks.c
index 59ba9a7..61d19e4 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -1456,6 +1456,19 @@ default_debug_unwind_info (void)
   return UI_NONE;
 }
 
+/* Determine the correct mode for a Dwarf frame register that represents
+   register REGNO.  */
+
+enum machine_mode
+default_dwarf_frame_reg_mode (int regno)
+{
+  enum machine_mode save_mode = reg_raw_mode[regno];
+
+  if (HARD_REGNO_CALL_PART_CLOBBERED (regno, save_mode))
+    save_mode = choose_hard_reg_mode (regno, 1, true);
+  return save_mode;
+}
+
 /* To be used by targets where reg_raw_mode doesn't return the right
    mode for registers used in apply_builtin_return and apply_builtin_arg.  */
 
diff --git a/gcc/targhooks.h b/gcc/targhooks.h
index bbc9a82..0a1f6e9 100644
--- a/gcc/targhooks.h
+++ b/gcc/targhooks.h
@@ -194,6 +194,7 @@ extern int default_label_align_max_skip (rtx);
 extern int default_jump_align_max_skip (rtx);
 extern section * default_function_section(tree decl, enum node_frequency freq,
 					  bool startup, bool exit);
+extern enum machine_mode default_dwarf_frame_reg_mode (int);
 extern enum machine_mode default_get_reg_raw_mode (int);
 extern bool default_keep_leaf_when_profiled ();