[Bug optimization/10817] gcc does not optimize result=0;if(t!=0)result=t; to result=t;

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10817



------- Additional Comments From cvs-commit at gcc dot gnu dot org  2003-11-02 13:56 -------
Subject: Bug 10817

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	sayle@gcc.gnu.org	2003-11-02 13:56:42

Modified files:
	gcc            : ChangeLog ifcvt.c simplify-rtx.c 
	gcc/testsuite  : ChangeLog 
Added files:
	gcc/testsuite/gcc.c-torture/compile: 20031102-1.c 

Log message:
	PR optimization/10817
	* ifcvt.c (noce_emit_move_insn): Improve documentation comment.
	(noce_try_move): New function to optimize an if-the-else into an
	unconditional move, i.e. "if (a!=b) x=a; else x=b" into "x=a".
	(noce_process_if_block): Attempt simplification with noce_try_move.
	
	* simplify-rtx.c (simplify_ternary_operation): Some minor fixes
	and improvements to the optimizations of IF_THEN_ELSE expressions.
	(simplify_subreg): Silence signed/unsigned comparison warning.
	
	* gcc.c-torture/compile/20031102-1.c: New test case.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.1652&r2=2.1653
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ifcvt.c.diff?cvsroot=gcc&r1=1.128&r2=1.129
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/simplify-rtx.c.diff?cvsroot=gcc&r1=1.164&r2=1.165
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.3164&r2=1.3165
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.c-torture/compile/20031102-1.c.diff?cvsroot=gcc&r1=NONE&r2=1.1