From: Alan Hayward <alan.hayward@arm.com>
Date: Wed, 21 Jan 2015 17:53:04 +0000 (+0000)
Subject: rtlanal.c (subreg_get_info): Exit early for simple and common cases.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=9ab41c76dd2db2e2880a17eb4e6d760a087dfa45;p=gcc.git

rtlanal.c (subreg_get_info): Exit early for simple and common cases.

gcc/
2015-01-25  Alan Hayward  <alan.hayward@arm.com>

	* rtlanal.c (subreg_get_info): Exit early for simple and common
	cases.

From-SVN: r219957
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3f1dda4188d..40422a38d54 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2015-01-21  Alan Hayward  <alan.hayward@arm.com>
+
+	* rtlanal.c (subreg_get_info): Exit early for simple and common
+	cases.
+
 2015-01-21  Richard Henderson  <rth@redhat.com>
 
 	PR target/64669
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index 513feeb577b..743aad6705c 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -3440,6 +3440,22 @@ subreg_get_info (unsigned int xregno, machine_mode xmode,
 	  info->offset = offset / regsize_xmode;
 	  return;
 	}
+      /* Quick exit for the simple and common case of extracting whole
+	 subregisters from a multiregister value.  */
+      /* ??? It would be better to integrate this into the code below,
+	 if we can generalize the concept enough and figure out how
+	 odd-sized modes can coexist with the other weird cases we support.  */
+      if (!rknown
+	  && WORDS_BIG_ENDIAN == REG_WORDS_BIG_ENDIAN
+	  && regsize_xmode == regsize_ymode
+	  && (offset % regsize_ymode) == 0)
+	{
+	  info->representable_p = true;
+	  info->nregs = nregs_ymode;
+	  info->offset = offset / regsize_ymode;
+	  gcc_assert (info->offset + info->nregs <= nregs_xmode);
+	  return;
+	}
     }
 
   /* Lowpart subregs are otherwise valid.  */