From 04c5580f371b08c0cccb05a520b69097512e3f62 Mon Sep 17 00:00:00 2001
From: Jan Hubicka <jh@suse.cz>
Date: Fri, 18 Apr 2003 01:31:41 +0200
Subject: emit-rtl.c (subreg_hard_regno): Check that register is representable.

	* emit-rtl.c (subreg_hard_regno):  Check that register is representable.
	* reload.c (reload_inner_reg_of_subreg):  When register is not
	representable, reload the whole thing.
	(find_reloads): Likewsie.
	* rtlanal.c (subreg_representable_p):  New function.

	* profile.c (compute_branch_probabilities):  Cleanup sanity checking;
	allow negative probabilities for edges from the call to exit.
	(branch_prob): Do not add fake edges for functions that may return twice

From-SVN: r65757
---
 gcc/rtlanal.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

(limited to 'gcc/rtlanal.c')

diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index f7923c2..3b024ad 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -3387,6 +3387,77 @@ subreg_regno_offset (xregno, xmode, offset, ymode)
   return (y_offset / (mode_multiple / nregs_multiple)) * nregs_ymode;
 }
 
+/* This function returns true when the offset is representable via
+   subreg_offset in the given regno.
+   xregno - A regno of an inner hard subreg_reg (or what will become one).
+   xmode  - The mode of xregno.
+   offset - The byte offset.
+   ymode  - The mode of a top level SUBREG (or what may become one).
+   RETURN - The regno offset which would be used.  */
+bool
+subreg_offset_representable_p (xregno, xmode, offset, ymode)
+     unsigned int xregno;
+     enum machine_mode xmode;
+     unsigned int offset;
+     enum machine_mode ymode;
+{
+  int nregs_xmode, nregs_ymode;
+  int mode_multiple, nregs_multiple;
+  int y_offset;
+
+  if (xregno >= FIRST_PSEUDO_REGISTER)
+    abort ();
+
+  nregs_xmode = HARD_REGNO_NREGS (xregno, xmode);
+  nregs_ymode = HARD_REGNO_NREGS (xregno, ymode);
+
+  /* paradoxical subregs are always valid.  */
+  if (offset == 0
+      && nregs_ymode > nregs_xmode
+      && (GET_MODE_SIZE (ymode) > UNITS_PER_WORD
+	  ? WORDS_BIG_ENDIAN : BYTES_BIG_ENDIAN))
+    return true;
+
+  /* Lowpart subregs are always valid.  */
+  if (offset == subreg_lowpart_offset (ymode, xmode))
+    return true;
+
+#ifdef ENABLE_CHECKING
+  /* This should always pass, otherwise we don't know how to verify the
+     constraint. 
+
+     These conditions may be relaxed but subreg_offset would need to be
+     redesigned.  */
+  if (GET_MODE_SIZE (xmode) % GET_MODE_SIZE (ymode)
+      || GET_MODE_SIZE (ymode) % nregs_ymode
+      || mode_for_size (GET_MODE_SIZE (ymode) / nregs_ymode,
+	      		MODE_INT, 0) == VOIDmode
+      || nregs_xmode % nregs_ymode)
+    abort ();
+#endif
+
+  /* The XMODE value can be seen as an vector of NREGS_XMODE
+     values.  The subreg must represent an lowpart of given field.
+     Compute what field it is.  */
+  offset -= subreg_lowpart_offset (mode_for_size (GET_MODE_SIZE (ymode)
+			  			  / nregs_ymode,
+						  MODE_INT, 0), xmode);
+
+  /* size of ymode must not be greater than the size of xmode.  */
+  mode_multiple = GET_MODE_SIZE (xmode) / GET_MODE_SIZE (ymode);
+  if (mode_multiple == 0)
+    abort ();
+
+  y_offset = offset / GET_MODE_SIZE (ymode);
+  nregs_multiple =  nregs_xmode / nregs_ymode;
+#ifdef ENABLE_CHECKING
+  if (offset % GET_MODE_SIZE (ymode)
+      || mode_multiple % nregs_multiple)
+    abort ();
+#endif
+  return (!(y_offset % (mode_multiple / nregs_multiple)));
+}
+
 /* Return the final regno that a subreg expression refers to.  */
 unsigned int
 subreg_regno (x)
-- 
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