re PR middle-end/86627 (Signed 128-bit division by 2 no longer expanded to RTL)

	PR middle-end/86627
	* expmed.c (expand_divmod): Punt if d == HOST_WIDE_INT_MIN
	and size > HOST_BITS_PER_WIDE_INT.  For size > HOST_BITS_PER_WIDE_INT
	and abs_d == d, do the power of two handling if profitable.

	* gcc.target/i386/pr86627.c: New test.

From-SVN: r262948

gcc/ChangeLog

+2018-07-24  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/86627
+	* expmed.c (expand_divmod): Punt if d == HOST_WIDE_INT_MIN
+	and size > HOST_BITS_PER_WIDE_INT.  For size > HOST_BITS_PER_WIDE_INT
+	and abs_d == d, do the power of two handling if profitable.
+
 2018-07-24  Richard Biener  <rguenther@suse.de>
 
 	* match.pd: Add BIT_FIELD_REF canonicalizations.

gcc/expmed.c

@@ -4480,6 +4480,11 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
 		HOST_WIDE_INT d = INTVAL (op1);
 		unsigned HOST_WIDE_INT abs_d;
 
+		/* Not prepared to handle division/remainder by
+		   0xffffffffffffffff8000000000000000 etc.  */
+		if (d == HOST_WIDE_INT_MIN && size > HOST_BITS_PER_WIDE_INT)
+		  break;
+
 		/* Since d might be INT_MIN, we have to cast to
 		   unsigned HOST_WIDE_INT before negating to avoid
 		   undefined signed overflow.  */
@@ -4522,9 +4527,7 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
 			     || (optab_handler (sdivmod_optab, int_mode)
 				 != CODE_FOR_nothing)))
 		  ;
-		else if (EXACT_POWER_OF_2_OR_ZERO_P (abs_d)
-			 && (size <= HOST_BITS_PER_WIDE_INT
-			     || abs_d != (unsigned HOST_WIDE_INT) d))
+		else if (EXACT_POWER_OF_2_OR_ZERO_P (abs_d))
 		  {
 		    if (rem_flag)
 		      {

gcc/testsuite/ChangeLog

 2018-07-24  Jakub Jelinek  <jakub@redhat.com>
 
+	PR middle-end/86627
+	* gcc.target/i386/pr86627.c: New test.
+
 	PR testsuite/86649
 	* g++.dg/tree-ssa-/pr19476-1.C: Check dom2 dump instead of ccp1.
 	* g++.dg/tree-ssa-/pr19476-5.C: Likewise.

gcc/testsuite/gcc.target/i386/pr86627.c

+/* PR middle-end/86627 */
+/* { dg-do compile { target int128 } } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-not "call\[^\n\r]*__divti3" } } */
+
+__int128_t
+f1 (__int128_t a)
+{
+  return a / 2;
+}
+
+__int128_t
+f2 (__int128_t a)
+{
+  return a / -2;
+}
+
+__int128_t
+f3 (__int128_t a)
+{
+  return a / 0x4000000000000000LL;
+}
+
+__int128_t
+f4 (__int128_t a)
+{
+  return a / -0x4000000000000000LL;
+}