2019-08-30  Jakub Jelinek  <jakub@redhat.com>

	Backported from mainline
	2019-02-20  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/88074
	PR middle-end/89415
	* toplev.c (do_compile): Double the emin/emax exponents to workaround
	buggy mpc_norm.

	2019-02-19  Richard Biener  <rguenther@suse.de>

        PR middle-end/88074
	* toplev.c (do_compile): Initialize mpfr's exponent range
	based on available float modes.

	2019-02-20  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/88074
	PR middle-end/89415
	* gcc.dg/pr88074-2.c: New test.

	2019-02-19  Richard Biener  <rguenther@suse.de>

        PR middle-end/88074
	* gcc.dg/pr88074.c: New testcase.

--- gcc/toplev.c	(revision 270711)
+++ gcc/toplev.c	(revision 270712)
@@ -1981,6 +1981,36 @@ do_compile ()
 	else
 	  int_n_enabled_p[i] = false;
 
+      /* Initialize mpfrs exponent range.  This is important to get
+         underflow/overflow in a reasonable timeframe.  */
+      machine_mode mode;
+      int min_exp = -1;
+      int max_exp = 1;
+      for (mode = GET_CLASS_NARROWEST_MODE (MODE_FLOAT);
+	   mode != VOIDmode;
+	   mode = GET_MODE_WIDER_MODE (mode))
+	if (SCALAR_FLOAT_MODE_P (mode))
+	  {
+	    const real_format *fmt = REAL_MODE_FORMAT (mode);
+	    if (fmt)
+	      {
+		/* fmt->emin - fmt->p + 1 should be enough but the
+		   back-and-forth dance in real_to_decimal_for_mode we
+		   do for checking fails due to rounding effects then.  */
+		if ((fmt->emin - fmt->p) < min_exp)
+		  min_exp = fmt->emin - fmt->p;
+		if (fmt->emax > max_exp)
+		  max_exp = fmt->emax;
+	      }
+	  }
+      /* E.g. mpc_norm assumes it can square a number without bothering with
+	 with range scaling, so until that is fixed, double the minimum
+	 and maximum exponents, plus add some buffer for arithmetics
+	 on the squared numbers.  */
+      if (mpfr_set_emin (2 * (min_exp - 1))
+	  || mpfr_set_emax (2 * (max_exp + 1)))
+	sorry ("mpfr not configured to handle all float modes");
+
       /* Set up the back-end if requested.  */
       if (!no_backend)
 	backend_init ();
--- gcc/testsuite/gcc.dg/pr88074.c	(nonexistent)
+++ gcc/testsuite/gcc.dg/pr88074.c	(revision 270712)
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+#include <complex.h>
+
+int main()
+{
+  _Complex double x;
+  __real x = 3.091e+8;
+  __imag x = -4.045e+8;
+  /* This used to spend huge amounts of compile-time inside mpc.  */
+  volatile _Complex double y = ctan (x);
+  return 0;
+}
--- gcc/testsuite/gcc.dg/pr88074-2.c	(nonexistent)
+++ gcc/testsuite/gcc.dg/pr88074-2.c	(revision 270712)
@@ -0,0 +1,17 @@
+/* PR middle-end/88074 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* { dg-add-options float128 } */
+/* { dg-require-effective-target float128 } */
+/* { dg-final { scan-tree-dump-not "link_error " "optimized" } } */
+
+extern void link_error (void);
+int
+main ()
+{
+  if (((__FLT128_MAX__ * 0.5 + __FLT128_MAX__ * 0.5i)
+       / (__FLT128_MAX__ * 0.25 + __FLT128_MAX__ * 0.25i))
+      != (_Complex _Float128) 2)
+    link_error ();
+  return 0;
+}