From: Geoff Keating <geoffk@cygnus.com>
Date: Sun, 28 May 2000 01:06:11 +0000 (+0000)
Subject: combine.c (subst): Honour CLASS_CANNOT_CHANGE_SIZE when substituting the REG in a... 
X-Git-Tag: prereleases/libstdc++-2.92~6140
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ed8afe3ab07e9ed5cd22900331946b0d19eb6a04;p=thirdparty%2Fgcc.git

combine.c (subst): Honour CLASS_CANNOT_CHANGE_SIZE when substituting the REG in a (subreg:X (reg:Y...

* combine.c (subst): Honour CLASS_CANNOT_CHANGE_SIZE when
substituting the REG in a (subreg:X (reg:Y ...)).

From-SVN: r34217
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a2d525367eac..f491f3c7edf9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2000-05-27  Geoff Keating  <geoffk@cygnus.com>
+
+	* combine.c (subst): Honour CLASS_CANNOT_CHANGE_SIZE when
+	substituting the REG in a (subreg:X (reg:Y ...)).
+
 2000-05-28  Neil Booth  <NeilB@earthling.net>
 
 	* cpplex.c (_cpp_lex_line): Merge vertical space.  Flag
diff --git a/gcc/combine.c b/gcc/combine.c
index c9d6a52f294c..8a14d806c68e 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -3400,6 +3400,18 @@ subst (x, from, to, in_dest, unique_copy)
 		      )
 		    return gen_rtx_CLOBBER (VOIDmode, const0_rtx);
 
+#ifdef CLASS_CANNOT_CHANGE_SIZE
+		  if (code == SUBREG
+		      && GET_CODE (to) == REG
+		      && REGNO (to) < FIRST_PSEUDO_REGISTER
+		      && (TEST_HARD_REG_BIT
+			  (reg_class_contents[(int) CLASS_CANNOT_CHANGE_SIZE],
+			   REGNO (to)))
+		      && (GET_MODE_BITSIZE (GET_MODE (to)) 
+			  != GET_MODE_BITSIZE (GET_MODE (x))))
+		    return gen_rtx_CLOBBER (VOIDmode, const0_rtx);
+#endif
+
 		  new = (unique_copy && n_occurrences ? copy_rtx (to) : to);
 		  n_occurrences++;
 		}