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[PATCH] Fix ix86_split_long_move collision handling with TLS (PR target/66470)


Hi!

As mentioned in the PR, when trying to split:
(insn 7 15 13 2 (set (reg:DI 0 ax [92])
        (mem:DI (plus:SI (plus:SI (mult:SI (reg/v:SI 1 dx [orig:89 b ] [89])
                        (const_int 8 [0x8]))
                    (unspec:SI [
                            (const_int 0 [0])
                        ] UNSPEC_TP))
                (reg:SI 0 ax [91])) [1 a S8 A64])) rh1212265.i:2 85 {*movdi_internal}
     (nil))
which has collisions == 2 (both ax and dx used on lhs and both
ax and dx used in the memory address), we generate invalid insn
- lea with %gs: or %fs: in it.  This patch fixes it by using
normal lea instead (so remove the unspec UNSPEC_TP from the address
for lea) and duplicating the unspec UNSPEC_TP to all the memory loads.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk/5/4.9/4.8?

2015-06-09  Jakub Jelinek  <jakub@redhat.com>

	PR target/66470
	* config/i386/i386.c (ix86_split_long_move): For collisions
	involving direct tls segment refs, move the UNSPEC_TP out of
	the address for lea, to each of the memory loads.

	* gcc.dg/tls/pr66470.c: New test.

--- gcc/config/i386/i386.c.jj	2015-06-08 15:41:19.000000000 +0200
+++ gcc/config/i386/i386.c	2015-06-09 11:50:29.960859723 +0200
@@ -22866,7 +22866,7 @@ ix86_split_long_move (rtx operands[])
 	 Do an lea to the last part and use only one colliding move.  */
       else if (collisions > 1)
 	{
-	  rtx base;
+	  rtx base, addr, tls_base = NULL_RTX;
 
 	  collisions = 1;
 
@@ -22877,10 +22877,45 @@ ix86_split_long_move (rtx operands[])
 	  if (GET_MODE (base) != Pmode)
 	    base = gen_rtx_REG (Pmode, REGNO (base));
 
-	  emit_insn (gen_rtx_SET (base, XEXP (part[1][0], 0)));
+	  addr = XEXP (part[1][0], 0);
+	  if (TARGET_TLS_DIRECT_SEG_REFS)
+	    {
+	      struct ix86_address parts;
+	      int ok = ix86_decompose_address (addr, &parts);
+	      gcc_assert (ok);
+	      if (parts.seg == DEFAULT_TLS_SEG_REG)
+		{
+		  /* It is not valid to use %gs: or %fs: in
+		     lea though, so we need to remove it from the
+		     address used for lea and add it to each individual
+		     memory loads instead.  */
+		  addr = copy_rtx (addr);
+		  rtx *x = &addr;
+		  while (GET_CODE (*x) == PLUS)
+		    {
+		      for (i = 0; i < 2; i++)
+			if (GET_CODE (XEXP (*x, i)) == UNSPEC
+			    && XINT (XEXP (*x, i), 1) == UNSPEC_TP)
+			  {
+			    tls_base = XEXP (*x, i);
+			    *x = XEXP (*x, 1 - i);
+			    break;
+			  }
+		      if (tls_base)
+			break;
+		      x = &XEXP (*x, 0);
+		    }
+		  gcc_assert (tls_base);
+		}
+	    }
+	  emit_insn (gen_rtx_SET (base, addr));
+	  if (tls_base)
+	    base = gen_rtx_PLUS (GET_MODE (base), base, tls_base);
 	  part[1][0] = replace_equiv_address (part[1][0], base);
 	  for (i = 1; i < nparts; i++)
 	    {
+	      if (tls_base)
+		base = copy_rtx (base);
 	      tmp = plus_constant (Pmode, base, UNITS_PER_WORD * i);
 	      part[1][i] = replace_equiv_address (part[1][i], tmp);
 	    }
--- gcc/testsuite/gcc.dg/tls/pr66470.c.jj	2015-06-09 11:59:05.543954781 +0200
+++ gcc/testsuite/gcc.dg/tls/pr66470.c	2015-06-09 11:58:43.000000000 +0200
@@ -0,0 +1,29 @@
+/* PR target/66470 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-require-effective-target tls } */
+
+extern __thread unsigned long long a[10];
+extern __thread struct S { int a, b; } b[10];
+
+unsigned long long
+foo (long x)
+{
+  return a[x];
+}
+
+struct S
+bar (long x)
+{
+  return b[x];
+}
+
+#ifdef __SIZEOF_INT128__
+extern __thread unsigned __int128 c[10];
+
+unsigned __int128
+baz (long x)
+{
+  return c[x];
+}
+#endif

	Jakub


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