From bd3647bf76d1d207eaa80c7c6b5a460fecc327a9 Mon Sep 17 00:00:00 2001
From: Jakub Jelinek <jakub@redhat.com>
Date: Thu, 23 May 2013 11:17:34 +0200
Subject: re PR rtl-optimization/57344 (wrong code with pragma pack(1) and -O1
 on x86)

	PR middle-end/57344
	* expmed.c (store_split_bit_field): If op0 is a REG or
	SUBREG of a REG, don't lower unit.  Handle unit not being
	always BITS_PER_WORD.

	* gcc.c-torture/execute/pr57344-1.c: New test.
	* gcc.c-torture/execute/pr57344-2.c: New test.
	* gcc.c-torture/execute/pr57344-3.c: New test.
	* gcc.c-torture/execute/pr57344-4.c: New test.

From-SVN: r199238
---
 gcc/expmed.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

(limited to 'gcc/expmed.c')

diff --git a/gcc/expmed.c b/gcc/expmed.c
index c85e68c..daadd3d 100644
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -1094,10 +1094,14 @@ store_split_bit_field (rtx op0, unsigned HOST_WIDE_INT bitsize,
       thispos = (bitpos + bitsdone) % unit;
 
       /* When region of bytes we can touch is restricted, decrease
-	 UNIT close to the end of the region as needed.  */
+	 UNIT close to the end of the region as needed.  If op0 is a REG
+	 or SUBREG of REG, don't do this, as there can't be data races
+	 on a register and we can expand shorter code in some cases.  */
       if (bitregion_end
 	  && unit > BITS_PER_UNIT
-	  && bitpos + bitsdone - thispos + unit > bitregion_end + 1)
+	  && bitpos + bitsdone - thispos + unit > bitregion_end + 1
+	  && !REG_P (op0)
+	  && (GET_CODE (op0) != SUBREG || !REG_P (SUBREG_REG (op0))))
 	{
 	  unit = unit / 2;
 	  continue;
@@ -1147,14 +1151,15 @@ store_split_bit_field (rtx op0, unsigned HOST_WIDE_INT bitsize,
 	 the current word starting from the base register.  */
       if (GET_CODE (op0) == SUBREG)
 	{
-	  int word_offset = (SUBREG_BYTE (op0) / UNITS_PER_WORD) + offset;
+	  int word_offset = (SUBREG_BYTE (op0) / UNITS_PER_WORD)
+			    + (offset * unit / BITS_PER_WORD);
 	  enum machine_mode sub_mode = GET_MODE (SUBREG_REG (op0));
 	  if (sub_mode != BLKmode && GET_MODE_SIZE (sub_mode) < UNITS_PER_WORD)
 	    word = word_offset ? const0_rtx : op0;
 	  else
 	    word = operand_subword_force (SUBREG_REG (op0), word_offset,
 					  GET_MODE (SUBREG_REG (op0)));
-	  offset = 0;
+	  offset &= BITS_PER_WORD / unit - 1;
 	}
       else if (REG_P (op0))
 	{
@@ -1162,8 +1167,9 @@ store_split_bit_field (rtx op0, unsigned HOST_WIDE_INT bitsize,
 	  if (op0_mode != BLKmode && GET_MODE_SIZE (op0_mode) < UNITS_PER_WORD)
 	    word = offset ? const0_rtx : op0;
 	  else
-	    word = operand_subword_force (op0, offset, GET_MODE (op0));
-	  offset = 0;
+	    word = operand_subword_force (op0, offset * unit / BITS_PER_WORD,
+					  GET_MODE (op0));
+	  offset &= BITS_PER_WORD / unit - 1;
 	}
       else
 	word = op0;
-- 
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