This backport contains 1 patch from gcc main stream tree.
The commit id of these patchs list as following in the order of time.

0001-combine-Don-t-generate-IF_THEN_ELSE.patch
ddbb5da5199fb421dc398911c37fa7f896efc13f

diff --git a/gcc/combine.c b/gcc/combine.c
index 4de759a8e6b..ce7aeecb5c2 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -5909,14 +5909,6 @@ combine_simplify_rtx (rtx x, machine_mode op0_mode, int in_dest,
 								 mode, VOIDmode,
 								 cond, cop1),
 					mode);
-	      else
-		return gen_rtx_IF_THEN_ELSE (mode,
-					     simplify_gen_relational (cond_code,
-								      mode,
-								      VOIDmode,
-								      cond,
-								      cop1),
-					     true_rtx, false_rtx);
 
 	      code = GET_CODE (x);
 	      op0_mode = VOIDmode;