From: Jakub Jelinek <jakub@redhat.com>
Date: Fri, 12 Oct 2018 14:53:11 +0000 (+0200)
Subject: backport: re PR middle-end/86627 (Signed 128-bit division by 2 no longer expanded... 
X-Git-Tag: releases/gcc-7.4.0~105
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5dd76907d07ee1145d7a5ff8b9c0983695da404b;p=thirdparty%2Fgcc.git

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

	Backported from mainline
	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.

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

From-SVN: r265109
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6f147d3a1b28..8363ff264063 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,6 +1,13 @@
 2018-10-12  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	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.
+
 	2018-07-17  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/86542
diff --git a/gcc/expmed.c b/gcc/expmed.c
index 30001ac0a713..b9f12576b0cf 100644
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -4314,6 +4314,11 @@ 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.  */
@@ -4357,9 +4362,7 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
 						compute_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)
 		      {
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index d8a76b9b5122..c9f55dda7527 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,6 +1,11 @@
 2018-10-12  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2018-07-24  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/86627
+	* gcc.target/i386/pr86627.c: New test.
+
 	2018-07-10  Jakub Jelinek  <jakub@redhat.com>
 
 	PR fortran/86421
diff --git a/gcc/testsuite/gcc.target/i386/pr86627.c b/gcc/testsuite/gcc.target/i386/pr86627.c
new file mode 100644
index 000000000000..5aefbed0a0b9
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr86627.c
@@ -0,0 +1,28 @@
+/* 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;
+}