re PR middle-end/52592 (compilation failure with undefined reference to `__builtin_iround')

	PR middle-end/52592
	* builtins.c (expand_builtin_int_roundingfn_2): If expanding
	BUILT_IN_IR{INT,OUND}* using optab fails, emit lr{int,ound}*
	calls instead of __builtin_ir{int,ound}*.

	* gcc.dg/pr52592.c: New test.

Co-Authored-By: Andrew Pinski <apinski@cavium.com>

From-SVN: r185431

1 files changed, 52 insertions, 23 deletions

diff --git a/gcc/builtins.c b/gcc/builtins.c
index b937d3d..a086a8c 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -2841,10 +2841,7 @@ expand_builtin_int_roundingfn_2 (tree exp, rtx target)
   tree fndecl = get_callee_fndecl (exp);
   tree arg;
   enum machine_mode mode;
-
-  /* There's no easy way to detect the case we need to set EDOM.  */
-  if (flag_errno_math)
-    return NULL_RTX;
+  enum built_in_function fallback_fn = BUILT_IN_NONE;
 
   if (!validate_arglist (exp, REAL_TYPE, VOID_TYPE))
      gcc_unreachable ();
@@ -2854,46 +2851,78 @@ expand_builtin_int_roundingfn_2 (tree exp, rtx target)
   switch (DECL_FUNCTION_CODE (fndecl))
     {
     CASE_FLT_FN (BUILT_IN_IRINT):
+      fallback_fn = BUILT_IN_LRINT;
+      /* FALLTHRU */
     CASE_FLT_FN (BUILT_IN_LRINT):
     CASE_FLT_FN (BUILT_IN_LLRINT):
-      builtin_optab = lrint_optab; break;
+      builtin_optab = lrint_optab;
+      break;
 
     CASE_FLT_FN (BUILT_IN_IROUND):
+      fallback_fn = BUILT_IN_LROUND;
+      /* FALLTHRU */
     CASE_FLT_FN (BUILT_IN_LROUND):
     CASE_FLT_FN (BUILT_IN_LLROUND):
-      builtin_optab = lround_optab; break;
+      builtin_optab = lround_optab;
+      break;
 
     default:
       gcc_unreachable ();
     }
 
+  /* There's no easy way to detect the case we need to set EDOM.  */
+  if (flag_errno_math && fallback_fn == BUILT_IN_NONE)
+    return NULL_RTX;
+
   /* Make a suitable register to place result in.  */
   mode = TYPE_MODE (TREE_TYPE (exp));
 
-  target = gen_reg_rtx (mode);
+  /* There's no easy way to detect the case we need to set EDOM.  */
+  if (!flag_errno_math)
+    {
+      target = gen_reg_rtx (mode);
 
-  /* Wrap the computation of the argument in a SAVE_EXPR, as we may
-     need to expand the argument again.  This way, we will not perform
-     side-effects more the once.  */
-  CALL_EXPR_ARG (exp, 0) = arg = builtin_save_expr (arg);
+      /* Wrap the computation of the argument in a SAVE_EXPR, as we may
+	 need to expand the argument again.  This way, we will not perform
+	 side-effects more the once.  */
+      CALL_EXPR_ARG (exp, 0) = arg = builtin_save_expr (arg);
 
-  op0 = expand_expr (arg, NULL, VOIDmode, EXPAND_NORMAL);
+      op0 = expand_expr (arg, NULL, VOIDmode, EXPAND_NORMAL);
 
-  start_sequence ();
+      start_sequence ();
 
-  if (expand_sfix_optab (target, op0, builtin_optab))
-    {
-      /* Output the entire sequence.  */
-      insns = get_insns ();
+      if (expand_sfix_optab (target, op0, builtin_optab))
+	{
+	  /* Output the entire sequence.  */
+	  insns = get_insns ();
+	  end_sequence ();
+	  emit_insn (insns);
+	  return target;
+	}
+
+      /* If we were unable to expand via the builtin, stop the sequence
+	 (without outputting the insns) and call to the library function
+	 with the stabilized argument list.  */
       end_sequence ();
-      emit_insn (insns);
-      return target;
     }
 
-  /* If we were unable to expand via the builtin, stop the sequence
-     (without outputting the insns) and call to the library function
-     with the stabilized argument list.  */
-  end_sequence ();
+  if (fallback_fn != BUILT_IN_NONE)
+    {
+      /* Fall back to rounding to long int.  Use implicit_p 0 - for non-C99
+	 targets, (int) round (x) should never be transformed into
+	 BUILT_IN_IROUND and if __builtin_iround is called directly, emit
+	 a call to lround in the hope that the target provides at least some
+	 C99 functions.  This should result in the best user experience for
+	 not full C99 targets.  */
+      tree fallback_fndecl = mathfn_built_in_1 (TREE_TYPE (arg),
+						fallback_fn, 0);
+
+      exp = build_call_nofold_loc (EXPR_LOCATION (exp),
+				   fallback_fndecl, 1, arg);
+
+      target = expand_call (exp, NULL_RTX, target == const0_rtx);
+      return convert_to_mode (mode, target, 0);
+    }
 
   target = expand_call (exp, target, target == const0_rtx);