diff -r 000000000000 -r eeea35fbf182 patches/gcc/4.0.0/pr20973-fix.patch
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/patches/gcc/4.0.0/pr20973-fix.patch	Sat Feb 24 11:00:05 2007 +0000
@@ -0,0 +1,80 @@
+http://gcc.gnu.org/PR20973
+
+"gcc 4 (about RC1) miscompiles khtml, in fact something in CSS, which basically 
+leads to all websites being misrendered.  I can't easily reduce the testcase, 
+but have applied the whole preprocessed source of css/cssstyleselector.ii. 
+ 
+It is to be compiled with g++ -O2 -fPIC -march=i586 -mtune=i686 
+-fno-exceptions.  A more detailed analysis will follow, as we've found out 
+some things already."
+
+---
+
+Subject: Bug 20973
+
+CVSROOT:	/cvs/gcc
+Module name:	gcc
+Branch: 	gcc-4_0-branch
+Changes by:	matz@gcc.gnu.org	2005-04-22 17:30:21
+
+Modified files:
+	gcc            : ChangeLog reload.c 
+
+Log message:
+	PR middle-end/20973
+	* reload.c (push_reload, find_dummy_reload): Check for uninitialized
+	pseudos.
+
+Patches:
+http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=2.7592.2.177&r2=2.7592.2.178
+http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/reload.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.268&r2=1.268.2.1
+
+---
+
+===================================================================
+RCS file: /cvs/gcc/gcc/gcc/reload.c,v
+retrieving revision 1.268
+retrieving revision 1.268.2.1
+diff -u -r1.268 -r1.268.2.1
+--- gcc/gcc/reload.c	2005/02/24 22:06:06	1.268
++++ gcc/gcc/reload.c	2005/04/22 17:30:15	1.268.2.1
+@@ -1520,7 +1520,7 @@
+      But if there is no spilling in this block, that is OK.
+      An explicitly used hard reg cannot be a spill reg.  */
+ 
+-  if (rld[i].reg_rtx == 0 && in != 0)
++  if (rld[i].reg_rtx == 0 && in != 0 && hard_regs_live_known)
+     {
+       rtx note;
+       int regno;
+@@ -1534,6 +1534,11 @@
+ 	    && REG_P (XEXP (note, 0))
+ 	    && (regno = REGNO (XEXP (note, 0))) < FIRST_PSEUDO_REGISTER
+ 	    && reg_mentioned_p (XEXP (note, 0), in)
++	    /* Check that we don't use a hardreg for an uninitialized
++	       pseudo.  See also find_dummy_reload().  */
++	    && (ORIGINAL_REGNO (XEXP (note, 0)) < FIRST_PSEUDO_REGISTER
++		|| ! bitmap_bit_p (ENTRY_BLOCK_PTR->global_live_at_end,
++				   ORIGINAL_REGNO (XEXP (note, 0))))
+ 	    && ! refers_to_regno_for_reload_p (regno,
+ 					       (regno
+ 						+ hard_regno_nregs[regno]
+@@ -1997,7 +2002,17 @@
+ 				is a subreg, and in that case, out
+ 				has a real mode.  */
+ 			     (GET_MODE (out) != VOIDmode
+-			      ? GET_MODE (out) : outmode)))
++			      ? GET_MODE (out) : outmode))
++        /* But only do all this if we can be sure, that this input
++           operand doesn't correspond with an uninitialized pseudoreg.
++           global can assign some hardreg to it, which is the same as
++	   a different pseudo also currently live (as it can ignore the
++	   conflict).  So we never must introduce writes to such hardregs,
++	   as they would clobber the other live pseudo using the same.
++	   See also PR20973.  */
++      && (ORIGINAL_REGNO (in) < FIRST_PSEUDO_REGISTER
++          || ! bitmap_bit_p (ENTRY_BLOCK_PTR->global_live_at_end,
++			     ORIGINAL_REGNO (in))))
+     {
+       unsigned int regno = REGNO (in) + in_offset;
+       unsigned int nwords = hard_regno_nregs[regno][inmode];