From: Teresa Johnson <tejohnson@google.com>
Date: Fri, 26 Oct 2012 17:19:35 +0000 (+0000)
Subject: Avoid conservative behavior in REE by allowing removal of redundant extends when...
X-Git-Tag: releases/gcc-4.8.0~2522
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ca3f371f1246db1bf2b71abfdf844a08e0f5dc31;p=thirdparty%2Fgcc.git

Avoid conservative behavior in REE by allowing removal of redundant extends when...

Avoid conservative behavior in REE by allowing removal of redundant extends
when the def feeds another extend with a different mode. This works because
in merge_def_and_ext only calls combine_set_extension if the candidate for
removal has a wider mode than the def extend's mode, otherwise the def extend
mode is preserved. In combine_set_extension the def is modified to use the
wider candidate's mode.

2012-10-26  Teresa Johnson  <tejohnson@google.com>

	* ree.c (add_removable_extension): Remove unnecessary
	mode check with other extension.
	* testsuite/gcc.c-torture/execute/20111227-2.c: New test.
	* testsuite/gcc.c-torture/execute/20111227-3.c: Ditto.

From-SVN: r192850
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 768f530609c0..db8c3520563c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2012-10-26  Teresa Johnson  <tejohnson@google.com>
+
+	* ree.c (add_removable_extension): Remove unnecessary
+	mode check with other extension.
+	* testsuite/gcc.c-torture/execute/20111227-2.c: New test.
+	* testsuite/gcc.c-torture/execute/20111227-3.c: Ditto.
+
 2012-10-26  Jan Hubicka  <jh@suse.cz>
 
 	* ipa-inline-transform.c (inline_call): Only account size changes
diff --git a/gcc/ree.c b/gcc/ree.c
index 167efa3fe1dd..a2ede97b72e3 100644
--- a/gcc/ree.c
+++ b/gcc/ree.c
@@ -803,7 +803,7 @@ add_removable_extension (const_rtx expr, rtx insn,
       for (def = defs; def; def = def->next)
 	if ((idx = def_map[INSN_UID(DF_REF_INSN (def->ref))])
 	    && (cand = &VEC_index (ext_cand, *insn_list, idx - 1))
-	    && (cand->code != code || cand->mode != mode))
+	    && cand->code != code)
 	  {
 	    if (dump_file)
 	      {
diff --git a/gcc/testsuite/gcc.c-torture/execute/20111227-2.c b/gcc/testsuite/gcc.c-torture/execute/20111227-2.c
new file mode 100644
index 000000000000..692c947e9a8d
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/20111227-2.c
@@ -0,0 +1,44 @@
+/* Testcase derived from 20111227-1.c to ensure that REE is combining
+   redundant zero extends with zero extend to wider mode.  */
+/* { dg-options "-fdump-rtl-ree -O" } */
+extern void abort (void);
+
+unsigned short s;
+unsigned int i;
+unsigned long l;
+unsigned char v = -1;
+
+void __attribute__((noinline,noclone))
+bar (int t)
+{
+  if (t == 2 && s != 0xff)
+    abort ();
+  if (t == 1 && i != 0xff)
+    abort ();
+  if (t == 0 && l != 0xff)
+    abort ();
+}
+
+void __attribute__((noinline,noclone))
+foo (unsigned char *a, int t)
+{
+  unsigned char r = v;
+
+  if (t == 2)
+    s = (unsigned short) r;
+  else if (t == 1)
+    i = (unsigned int) r;
+  else if (t == 0)
+    l = (unsigned long) r;
+  bar (t);
+}
+
+int main(void)
+{
+  foo (&v, 0);
+  foo (&v, 1);
+  foo (&v, 2);
+  return 0;
+}
+/* { dg-final { scan-rtl-dump "Elimination opportunities = 3 realized = 3" "ree" } }  */
+/* { dg-final { cleanup-rtl-dump "ree" } }  */
diff --git a/gcc/testsuite/gcc.c-torture/execute/20111227-3.c b/gcc/testsuite/gcc.c-torture/execute/20111227-3.c
new file mode 100644
index 000000000000..d6726c473558
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/20111227-3.c
@@ -0,0 +1,45 @@
+/* Testcase derived from 20111227-1.c to ensure that REE is combining
+   redundant sign extends with sign extend to wider mode.  */
+/* { dg-options "-fdump-rtl-ree -O" } */
+
+extern void abort (void);
+
+signed short s;
+signed int i;
+signed long l;
+signed char v = -1;
+
+void __attribute__((noinline,noclone))
+bar (int t)
+{
+  if (t == 2 && s != -1)
+    abort ();
+  if (t == 1 && i != -1)
+    abort ();
+  if (t == 0 && l != -1)
+    abort ();
+}
+
+void __attribute__((noinline,noclone))
+foo (signed char *a, int t)
+{
+  signed char r = v;
+
+  if (t == 2)
+    s = (signed short) r;
+  else if (t == 1)
+    i = (signed int) r;
+  else if (t == 0)
+    l = (signed long) r;
+  bar (t);
+}
+
+int main(void)
+{
+  foo (&v, 0);
+  foo (&v, 1);
+  foo (&v, 2);
+  return 0;
+}
+/* { dg-final { scan-rtl-dump "Elimination opportunities = 3 realized = 3" "ree" } }  */
+/* { dg-final { cleanup-rtl-dump "ree" } }  */