From 198a0ce90f7f31eb196068569c1a27b188d642d7 Mon Sep 17 00:00:00 2001
From: aoliva <aoliva@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Wed, 7 Nov 2018 06:25:30 +0000
Subject: [PATCH] [PR87874] avoid const-wide-int subreg in LRA

Just like CONST_INT, CONST_WIDE_INT is VOIDmode, so LRA might be
tempted to build a SUBREG to "convert" it to the wanted mode.  That's
no use.  Test for CONST_SCALAR_INT_P instead of CONST_INT_P so that we
skip the subreg creation for both.

for  gcc/ChangeLog

	PR rtl-optimization/87874
	* lra.c (lra_substitute_pseudo): Do not create a subreg for
	const wide ints.

for  gcc/testsuite/ChangeLog

	PR rtl-optimization/87874
	* gcc.dg/pr87874.c: New.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@265860 138bc75d-0d04-0410-961f-82ee72b054a4
---
 gcc/ChangeLog                  |  6 ++++++
 gcc/lra.c                      |  2 +-
 gcc/testsuite/ChangeLog        |  5 +++++
 gcc/testsuite/gcc.dg/pr87874.c | 35 +++++++++++++++++++++++++++++++++++
 4 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr87874.c

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0c33c678a70..d1fde63c79c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-11-07  Alexandre Oliva <aoliva@redhat.com>
+
+	PR rtl-optimization/87874
+	* lra.c (lra_substitute_pseudo): Do not create a subreg for
+	const wide ints.
+
 2018-11-06  Aaron Sawdey  <acsawdey@linux.ibm.com>
 
 	* config/rs6000/rs6000.md (bswap<mode>2): Force address into register
diff --git a/gcc/lra.c b/gcc/lra.c
index aa768fb2a23..5d58d90f3a6 100644
--- a/gcc/lra.c
+++ b/gcc/lra.c
@@ -1961,7 +1961,7 @@ lra_substitute_pseudo (rtx *loc, int old_regno, rtx new_reg, bool subreg_p,
       machine_mode inner_mode = GET_MODE (new_reg);
 
       if (mode != inner_mode
-	  && ! (CONST_INT_P (new_reg) && SCALAR_INT_MODE_P (mode)))
+	  && ! (CONST_SCALAR_INT_P (new_reg) && SCALAR_INT_MODE_P (mode)))
 	{
 	  poly_uint64 offset = 0;
 	  if (partial_subreg_p (mode, inner_mode)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 4c1610dd169..66a09d6895e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-11-07  Alexandre Oliva <aoliva@redhat.com>
+
+	PR rtl-optimization/87874
+	* gcc.dg/pr87874.c: New.
+
 2018-11-06  Ilya Leoshkevich  <iii@linux.ibm.com>
 
 	* gcc.target/s390/load-and-test-fp-1.c: Accept cdb.
diff --git a/gcc/testsuite/gcc.dg/pr87874.c b/gcc/testsuite/gcc.dg/pr87874.c
new file mode 100644
index 00000000000..3ab5dcf68ff
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr87874.c
@@ -0,0 +1,35 @@
+/* { dg-do compile } */
+/* { dg-options "-g -O1 -fgcse -fno-dce -fno-tree-ccp -fno-tree-coalesce-vars -fno-tree-copy-prop -fno-tree-dce -fno-tree-dominator-opts -fno-tree-fre -fno-tree-loop-optimize -fno-tree-sink" } */
+
+int *vk;
+int m2;
+#if __SIZEOF_INT128__
+__int128 nb;
+
+void
+em (int u5, int fo, int s7)
+{
+  for (;;)
+    {
+      long int es;
+
+      es = !!u5 ? (!!fo && !!m2) : fo;
+      if (es == 0)
+        if (nb == *vk)
+          {
+            const unsigned long int uint64_max = 18446744073709551615ul;
+            __int128 ks = uint64_max / 2 + 1;
+
+            while (s7 < 1)
+              while (nb < 2)
+                {
+                  for (ks = 0; ks < 3; ++ks)
+                    {
+                    }
+
+                  ++nb;
+                }
+          }
+    }
+}
+#endif
-- 
2.11.4.GIT