Fwd: [PATCH, i386]: Remove special handling of memory operands from *testqi_ext_3

[Uros Bizjak]

Hello!

It turned out that recent changes made special handling of memory
operands in *testqi_ext_3 obsolete. Combine now always pass correct
width of memory operands for the extraction, as assured by added
assert.

2017-01-05  Uros Bizjak  <ubiz...@gmail.com>

    * config/i386/i386.md (*testqi_ext_3): No need to handle memory
    operands in a special way.  Assert that pos+len <= mode precision.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.

Committed to mainline SVN.

Uros.

Index: i386.md
===================================================================
--- i386.md     (revision 244058)
+++ i386.md     (working copy)
@@ -8007,36 +8007,30 @@
   rtx val = operands[2];
   HOST_WIDE_INT len = INTVAL (operands[3]);
   HOST_WIDE_INT pos = INTVAL (operands[4]);
-  machine_mode mode, submode;
+  machine_mode mode = GET_MODE (val);
 
-  mode = GET_MODE (val);
-  if (MEM_P (val))
+  if (SUBREG_P (val))
     {
-      /* ??? Combine likes to put non-volatile mem extractions in QImode
-        no matter the size of the test.  So find a mode that works.  */
-      if (! MEM_VOLATILE_P (val))
+      machine_mode submode = GET_MODE (SUBREG_REG (val));
+
+      /* Narrow paradoxical subregs to prevent partial register stalls.  */
+      if (GET_MODE_BITSIZE (mode) > GET_MODE_BITSIZE (submode)
+         && GET_MODE_CLASS (submode) == MODE_INT)
        {
-         mode = smallest_mode_for_size (pos + len, MODE_INT);
-         val = adjust_address (val, mode, 0);
+         val = SUBREG_REG (val);
+         mode = submode;
        }
     }
-  else if (SUBREG_P (val)
-          && (submode = GET_MODE (SUBREG_REG (val)),
-              GET_MODE_BITSIZE (mode) > GET_MODE_BITSIZE (submode))
-          && pos + len <= GET_MODE_BITSIZE (submode)
-          && GET_MODE_CLASS (submode) == MODE_INT)
+
+  /* Small HImode tests can be converted to QImode.  */
+  if (register_operand (val, HImode) && pos + len <= 8)
     {
-      /* Narrow a paradoxical subreg to prevent partial register stalls.  */
-      mode = submode;
-      val = SUBREG_REG (val);
-    }
-  else if (mode == HImode && pos + len <= 8)
-    {
-      /* Small HImode tests can be converted to QImode.  */
+      val = gen_lowpart (QImode, val);
       mode = QImode;
-      val = gen_lowpart (QImode, val);
     }
 
+  gcc_assert (pos + len <= GET_MODE_PRECISION (mode));
+
   wide_int mask
     = wi::shifted_mask (pos, len, false, GET_MODE_PRECISION (mode));