[PATCH, i386]: Fix PR78626, wrong code with -fschedule-insns

[Uros Bizjak]

Hello!

We need earlyclobber on output operand of doubleword shift insns,
since we have to prevent (partial) output matching %ecx as count
argument.

2016-11-09  Uros Bizjak  <ubiz...@gmail.com>

    PR target/78262
    * config/i386/i386.md (*<shift_insn><mode>3_doubleword): Mark
    operand 0 as earlyclobber.

testsuite/ChangeLog:

2016-11-09  Uros Bizjak  <ubiz...@gmail.com>

    PR target/78262
    * gcc.target/i386/pr78262.c: New test.

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

Committed to mainline, will be backported to release branches.

Uros.

Index: config/i386/i386.md
===================================================================
--- config/i386/i386.md (revision 242004)
+++ config/i386/i386.md (working copy)
@@ -10339,7 +10339,7 @@
   "operands[2] = gen_lowpart (QImode, operands[2]);")
 
 (define_insn_and_split "*<shift_insn><mode>3_doubleword"
-  [(set (match_operand:DWI 0 "register_operand" "=r")
+  [(set (match_operand:DWI 0 "register_operand" "=&r")
        (any_shiftrt:DWI (match_operand:DWI 1 "register_operand" "0")
                         (match_operand:QI 2 "nonmemory_operand" "<S>c")))
    (clobber (reg:CC FLAGS_REG))]
Index: testsuite/gcc.target/i386/pr78262.c
===================================================================
--- testsuite/gcc.target/i386/pr78262.c (nonexistent)
+++ testsuite/gcc.target/i386/pr78262.c (working copy)
@@ -0,0 +1,32 @@
+/* { dg-do run } */
+/* { dg-require-effective-target int128 } */
+/* { dg-options "-O -fschedule-insns" } */
+
+typedef unsigned char u8;
+typedef unsigned __int128 u128;
+
+static u128 u128_0;
+static u128 *p128;
+
+u128 __attribute__ ((noinline, noclone))
+foo(u8 u8_0)
+{
+  p128 = &u128_0;
+  u128_0 = u8_0;
+  u128_0 = u128_0 << 127 | u128_0 >> 1;
+  u128_0 >>= (u8)u128_0;
+  return 2 + u128_0;
+}
+
+int
+main()
+{
+  u128 x = foo(5);
+  if (p128 != &u128_0)
+    __builtin_abort();
+  if (u128_0 != ((u128)2 << 124))
+    __builtin_abort();
+  if (x != ((u128)2 << 124) + 2)
+    __builtin_abort();
+  return 0;
+}