From: Falk Hueffner <falk@debian.org>
Date: Sat, 27 Nov 2004 16:59:16 +0000 (+0100)
Subject: re PR rtl-optimization/18577 (variable use moved before initialization)
X-Git-Tag: releases/gcc-3.3.6~220
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=996e40f613e39df0e8bc4230aaa3357247121cf1;p=thirdparty%2Fgcc.git

re PR rtl-optimization/18577 (variable use moved before initialization)

	PR optimization/18577
	* unroll.c (unroll_loop): Test both REGNO_LAST_UID and
	REGNO_LAST_NOTE_UID to decide whether a pseudo is local
	to the loop.

Co-Authored-By: Eric Botcazou <ebotcazou@libertysurf.fr>

From-SVN: r91383
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index bbfd8f5efcd5..8882add1203b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2004-11-27  Falk Hueffner  <falk@debian.org>
+            Eric Botcazou  <ebotcazou@libertysurf.fr>
+
+	PR optimization/18577
+	* unroll.c (unroll_loop): Test both REGNO_LAST_UID and
+	REGNO_LAST_NOTE_UID to decide whether a pseudo is local
+	to the loop.
+
 2004-11-27  Alan Modra  <amodra@bigpond.net.au>
 
 	PR target/12769
diff --git a/gcc/regclass.c b/gcc/regclass.c
index 45c69d8b89a1..ecc630f42da3 100644
--- a/gcc/regclass.c
+++ b/gcc/regclass.c
@@ -2415,9 +2415,15 @@ reg_scan_mark_refs (x, insn, note_flag, min_regno)
 
 	if (regno >= min_regno)
 	  {
+	    /* While the following 3 lines means that the inequality
+	         REGNO_LAST_UID (regno) <= REGNO_LAST_NOTE_UID (regno)
+	       is true at the end of the scanning, it may be subsequently
+	       invalidated (e.g. in load_mems) so it should not be relied
+	       upon.  */
 	    REGNO_LAST_NOTE_UID (regno) = INSN_UID (insn);
 	    if (!note_flag)
 	      REGNO_LAST_UID (regno) = INSN_UID (insn);
+
 	    if (REGNO_FIRST_UID (regno) == 0)
 	      REGNO_FIRST_UID (regno) = INSN_UID (insn);
 	    /* If we are called by reg_scan_update() (indicated by min_regno
diff --git a/gcc/regs.h b/gcc/regs.h
index 2e838e329398..e823298614de 100644
--- a/gcc/regs.h
+++ b/gcc/regs.h
@@ -49,6 +49,9 @@ typedef struct reg_info_def
   int first_uid;		/* UID of first insn to use (REG n) */
   int last_uid;			/* UID of last insn to use (REG n) */
   int last_note_uid;		/* UID of last note to use (REG n) */
+				/* See the comment in reg_scan_mark_refs on
+				   the relationship between last_uid and
+				   last_note_uid.  */
 
 				/* fields set by reg_scan & flow_analysis */
   int sets;			/* # of times (REG n) is set */
diff --git a/gcc/unroll.c b/gcc/unroll.c
index a81420809180..8498874df41b 100644
--- a/gcc/unroll.c
+++ b/gcc/unroll.c
@@ -794,6 +794,10 @@ unroll_loop (loop, insn_count, strength_reduce_p)
       for (r = FIRST_PSEUDO_REGISTER; r < max_reg_before_loop; ++r)
 	if (REGNO_FIRST_UID (r) > 0 && REGNO_FIRST_UID (r) < max_uid_for_loop
 	    && REGNO_FIRST_LUID (r) >= copy_start_luid
+	    /* See the comment in reg_scan_mark_refs on the relationship between
+	       last_uid and last_note_uid.  */
+	    && REGNO_LAST_UID (r) > 0 && REGNO_LAST_UID (r) < max_uid_for_loop
+	    && REGNO_LAST_LUID (r) <= copy_end_luid
 	    && REGNO_LAST_NOTE_UID (r) > 0 && REGNO_LAST_NOTE_UID (r) < max_uid_for_loop
 	    && REGNO_LAST_NOTE_LUID (r) <= copy_end_luid)
 	  {