re PR target/66660 ([ia64] Speculative load not checked before use, leading to a…

re PR target/66660 ([ia64] Speculative load not checked before use, leading to a NaT Consumption Vector interruption)

        PR target/66660
        * sel-sched-ir.c (merge_expr): Avoid changing the speculative pattern
        to non-speculative when propagating trap bits.

From-SVN: r234218

gcc/sel-sched-ir.c

@@ -1871,12 +1871,16 @@ merge_expr (expr_t to, expr_t from, insn_t split_point)
   /* Make sure that speculative pattern is propagated into exprs that
      have non-speculative one.  This will provide us with consistent
      speculative bits and speculative patterns inside expr.  */
-  if ((EXPR_SPEC_DONE_DS (from) != 0
-       && EXPR_SPEC_DONE_DS (to) == 0)
-      /* Do likewise for volatile insns, so that we always retain
-	 the may_trap_p bit on the resulting expression.  */
-      || (VINSN_MAY_TRAP_P (EXPR_VINSN (from))
-	  && !VINSN_MAY_TRAP_P (EXPR_VINSN (to))))
+  if (EXPR_SPEC_DONE_DS (to) == 0
+      && (EXPR_SPEC_DONE_DS (from) != 0
+	  /* Do likewise for volatile insns, so that we always retain
+	     the may_trap_p bit on the resulting expression.  However,
+	     avoid propagating the trapping bit into the instructions
+	     already speculated.  This would result in replacing the
+	     speculative pattern with the non-speculative one and breaking
+	     the speculation support.  */
+	  || (!VINSN_MAY_TRAP_P (EXPR_VINSN (to))
+	      && VINSN_MAY_TRAP_P (EXPR_VINSN (from)))))
     change_vinsn_in_expr (to, EXPR_VINSN (from));
 
   merge_expr_data (to, from, split_point);