From: Richard Sandiford <richard.sandiford@arm.com>
Date: Tue, 15 Nov 2016 17:54:20 +0000 (+0000)
Subject: Move misplaced assignment in num_sign_bit_copies1
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=89e64bc0305f36a4abe486ce07cbee7c13a6dc81;p=gcc.git

Move misplaced assignment in num_sign_bit_copies1

The old assignment to bitwidth was before we handled VOIDmode with:

      if (mode == VOIDmode)
        mode = GET_MODE (x);

so when VOIDmode was specified we would always use:

      if (bitwidth < GET_MODE_PRECISION (GET_MODE (x)))
        {
          num0 = cached_num_sign_bit_copies (x, GET_MODE (x),
                                             known_x, known_mode, known_ret);
          return MAX (1,
                      num0 - (int) (GET_MODE_PRECISION (GET_MODE (x)) - bitwidth));
        }

For a zero bitwidth this always returns 1 (which is the most
pessimistic result).

gcc/
2016-11-15  Richard Sandiford  <richard.sandiford@arm.com>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

	* rtlanal.c (num_sign_bit_copies1): Calculate bitwidth after
	handling VOIDmode.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r242440
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f5ab2f3275f..95e3dc5047c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2016-11-15  Richard Sandiford  <richard.sandiford@arm.com>
+	    Alan Hayward  <alan.hayward@arm.com>
+	    David Sherwood  <david.sherwood@arm.com>
+
+	* rtlanal.c (num_sign_bit_copies1): Calculate bitwidth after
+	handling VOIDmode.
+
 2016-11-15  Matthias Klose  <doko@ubuntu.com>
 
 	* doc/install.texi: Remove references to gcj/libjava.
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index 4617e8ee449..e08f2be789b 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -4795,7 +4795,6 @@ num_sign_bit_copies1 (const_rtx x, machine_mode mode, const_rtx known_x,
 		      unsigned int known_ret)
 {
   enum rtx_code code = GET_CODE (x);
-  unsigned int bitwidth = GET_MODE_PRECISION (mode);
   machine_mode inner_mode;
   int num0, num1, result;
   unsigned HOST_WIDE_INT nonzero;
@@ -4811,7 +4810,8 @@ num_sign_bit_copies1 (const_rtx x, machine_mode mode, const_rtx known_x,
       || VECTOR_MODE_P (GET_MODE (x)) || VECTOR_MODE_P (mode))
     return 1;
 
-  /* For a smaller object, just ignore the high bits.  */
+  /* For a smaller mode, just ignore the high bits.  */
+  unsigned int bitwidth = GET_MODE_PRECISION (mode);
   if (bitwidth < GET_MODE_PRECISION (GET_MODE (x)))
     {
       num0 = cached_num_sign_bit_copies (x, GET_MODE (x),