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From a582b0a53d1dc8604a201348b99ca8de48784e7e Mon Sep 17 00:00:00 2001
From: jiwang <jiwang@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Thu, 12 May 2016 17:00:52 +0000
Subject: [PATCH] [LRA] PR70904, relax the restriction on subreg reload for
 wide mode

2016-05-12  Jiong Wang  <jiong.wang@arm.com>

gcc/
  PR rtl-optimization/70904
  * lra-constraint.c (process_addr_reg): Relax the restriction on
  subreg reload for wide mode.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@236181 138bc75d-0d04-0410-961f-82ee72b054a4
---
Upstream-Status: Backport
Signed-off-by: Khem Raj <raj.khem@gmail.com>

 gcc/lra-constraints.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/gcc/lra-constraints.c b/gcc/lra-constraints.c
index f96fd458e23..73fb72a2ea5 100644
--- a/gcc/lra-constraints.c
+++ b/gcc/lra-constraints.c
@@ -1326,7 +1326,21 @@ process_addr_reg (rtx *loc, bool check_only_p, rtx_insn **before, rtx_insn **aft
 
   subreg_p = GET_CODE (*loc) == SUBREG;
   if (subreg_p)
-    loc = &SUBREG_REG (*loc);
+    {
+      reg = SUBREG_REG (*loc);
+      mode = GET_MODE (reg);
+
+      /* For mode with size bigger than ptr_mode, there unlikely to be "mov"
+	 between two registers with different classes, but there normally will
+	 be "mov" which transfers element of vector register into the general
+	 register, and this normally will be a subreg which should be reloaded
+	 as a whole.  This is particularly likely to be triggered when
+	 -fno-split-wide-types specified.  */
+      if (in_class_p (reg, cl, &new_class)
+	  || GET_MODE_SIZE (mode) <= GET_MODE_SIZE (ptr_mode))
+       loc = &SUBREG_REG (*loc);
+    }
+
   reg = *loc;
   mode = GET_MODE (reg);
   if (! REG_P (reg))
-- 
2.14.2