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re PR tree-optimization/9814 (gcc fails to optimise if (l&2) l|=2 away)
PR tree-optimization/9814 * ifcvt.c (noce_emit_move_insn): If we fail to recognize the move instruction, add the necessary clobbers by re-expanding the RTL for arithmetic operations via optab.c's expand_unop/expand_binop. (noce_try_bitop): New function to optimize bit manipulation idioms of the form "if (x & C) x = x op C" and "if (!(x & C) x = x op C". (noce_process_if_block): Call noce_try_bitop. * gcc.dg/pr9814-1.c: New test case. From-SVN: r100240
This commit is contained in:
Roger Sayle
Roger Sayle
parent
2c9ed0af7e
commit
1acdf11bd5
@ -1,3 +1,13 @@
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2005-05-26 Roger Sayle <roger@eyesopen.com>
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PR tree-optimization/9814
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* ifcvt.c (noce_emit_move_insn): If we fail to recognize the move
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instruction, add the necessary clobbers by re-expanding the RTL
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for arithmetic operations via optab.c's expand_unop/expand_binop.
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(noce_try_bitop): New function to optimize bit manipulation idioms
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of the form "if (x & C) x = x op C" and "if (!(x & C) x = x op C".
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(noce_process_if_block): Call noce_try_bitop.
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2005-05-26 Roger Sayle <roger@eyesopen.com>
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* reg-stack.c (convert_regs_entry, convert_regs_exit,
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153
gcc/ifcvt.c
153
gcc/ifcvt.c
@ -687,7 +687,57 @@ noce_emit_move_insn (rtx x, rtx y)
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if (GET_CODE (x) != STRICT_LOW_PART)
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{
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emit_move_insn (x, y);
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rtx seq, insn, target;
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optab ot;
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start_sequence ();
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insn = emit_move_insn (x, y);
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seq = get_insns ();
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end_sequence();
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if (recog_memoized (insn) <= 0)
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switch (GET_RTX_CLASS (GET_CODE (y)))
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{
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case RTX_UNARY:
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ot = code_to_optab[GET_CODE (y)];
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if (ot)
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{
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start_sequence ();
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target = expand_unop (GET_MODE (y), ot, XEXP (y, 0), x, 0);
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if (target != NULL_RTX)
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{
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if (target != x)
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emit_move_insn (x, target);
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seq = get_insns ();
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}
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end_sequence ();
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}
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break;
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case RTX_BIN_ARITH:
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case RTX_COMM_ARITH:
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ot = code_to_optab[GET_CODE (y)];
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if (ot)
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{
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start_sequence ();
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target = expand_binop (GET_MODE (y), ot,
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XEXP (y, 0), XEXP (y, 1),
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x, 0, OPTAB_DIRECT);
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if (target != NULL_RTX)
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{
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if (target != x)
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emit_move_insn (x, target);
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seq = get_insns ();
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}
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end_sequence ();
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}
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break;
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default:
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break;
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}
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emit_insn (seq);
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return;
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}
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@ -1815,6 +1865,105 @@ noce_try_sign_mask (struct noce_if_info *if_info)
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}
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/* Optimize away "if (x & C) x |= C" and similar bit manipulation
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transformations. */
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static int
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noce_try_bitop (struct noce_if_info *if_info)
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{
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rtx cond, x, a, result, seq;
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enum machine_mode mode;
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enum rtx_code code;
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int bitnum;
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x = if_info->x;
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cond = if_info->cond;
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code = GET_CODE (cond);
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/* Check for no else condition. */
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if (! rtx_equal_p (x, if_info->b))
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return FALSE;
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/* Check for a suitable condition. */
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if (code != NE && code != EQ)
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return FALSE;
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if (XEXP (cond, 1) != const0_rtx)
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return FALSE;
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cond = XEXP (cond, 0);
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/* ??? We could also handle AND here. */
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if (GET_CODE (cond) == ZERO_EXTRACT)
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{
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if (XEXP (cond, 1) != const1_rtx
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|| GET_CODE (XEXP (cond, 2)) != CONST_INT
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|| ! rtx_equal_p (x, XEXP (cond, 0)))
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return FALSE;
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bitnum = INTVAL (XEXP (cond, 2));
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mode = GET_MODE (x);
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if (bitnum >= HOST_BITS_PER_WIDE_INT)
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return FALSE;
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}
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else
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return FALSE;
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a = if_info->a;
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if (GET_CODE (a) == IOR || GET_CODE (a) == XOR)
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{
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/* Check for "if (X & C) x = x op C". */
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if (! rtx_equal_p (x, XEXP (a, 0))
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|| GET_CODE (XEXP (a, 1)) != CONST_INT
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|| (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
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!= (unsigned HOST_WIDE_INT) 1 << bitnum)
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return FALSE;
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/* if ((x & C) == 0) x |= C; is transformed to x |= C. */
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/* if ((x & C) != 0) x |= C; is transformed to nothing. */
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if (GET_CODE (a) == IOR)
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result = (code == NE) ? a : NULL_RTX;
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else if (code == NE)
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{
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/* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
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result = gen_int_mode ((HOST_WIDE_INT) 1 << bitnum, mode);
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result = simplify_gen_binary (IOR, mode, x, result);
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}
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else
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{
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/* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
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result = gen_int_mode (~((HOST_WIDE_INT) 1 << bitnum), mode);
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result = simplify_gen_binary (AND, mode, x, result);
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}
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}
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else if (GET_CODE (a) == AND)
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{
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/* Check for "if (X & C) x &= ~C". */
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if (! rtx_equal_p (x, XEXP (a, 0))
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|| GET_CODE (XEXP (a, 1)) != CONST_INT
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|| (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
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!= (~((HOST_WIDE_INT) 1 << bitnum) & GET_MODE_MASK (mode)))
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return FALSE;
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/* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
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/* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
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result = (code == EQ) ? a : NULL_RTX;
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}
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else
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return FALSE;
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if (result)
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{
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start_sequence ();
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noce_emit_move_insn (x, result);
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seq = end_ifcvt_sequence (if_info);
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if (!seq)
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return FALSE;
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emit_insn_before_setloc (seq, if_info->jump,
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INSN_LOCATOR (if_info->insn_a));
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}
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return TRUE;
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}
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/* Similar to get_condition, only the resulting condition must be
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valid at JUMP, instead of at EARLIEST. */
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@ -2078,6 +2227,8 @@ noce_process_if_block (struct ce_if_block * ce_info)
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goto success;
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if (noce_try_store_flag (&if_info))
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goto success;
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if (noce_try_bitop (&if_info))
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goto success;
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if (noce_try_minmax (&if_info))
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goto success;
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if (noce_try_abs (&if_info))
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@ -1,3 +1,8 @@
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2005-05-26 Roger Sayle <roger@eyesopen.com>
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PR tree-optimization/9814
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* gcc.dg/pr9814-1.c: New test case.
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2005-05-26 Ziemowit Laski <zlaski@apple.com>
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* objc.dg/comp-types-8.m, objc.dg/encode-6.m,
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107
gcc/testsuite/gcc.dg/pr9814-1.c
Normal file
107
gcc/testsuite/gcc.dg/pr9814-1.c
Normal file
@ -0,0 +1,107 @@
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/* PR tree-optimization/9814 */
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/* { dg-do run } */
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/* { dg-options "-O2" } */
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extern void abort(void);
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int test1(int x)
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{
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if (x & 2)
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x |= 2;
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return x;
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}
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int test2(int x)
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{
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if (!(x & 2))
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x |= 2;
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return x;
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}
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int test3(int x)
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{
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if (x & 2)
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x ^= 2;
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return x;
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}
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int test4(int x)
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{
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if (!(x & 2))
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x ^= 2;
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return x;
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}
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int test5(int x)
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{
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if (x & 2)
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x &= ~2;
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return x;
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}
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int test6(int x)
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{
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if (!(x & 2))
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x &= ~2;
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return x;
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}
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int main()
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{
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if (test1(0) != 0)
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abort();
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if (test1(2) != 2)
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abort();
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if (test1(5) != 5)
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abort();
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if (test1(7) != 7)
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abort();
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if (test2(0) != 2)
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abort();
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if (test2(2) != 2)
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abort();
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if (test2(5) != 7)
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abort();
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if (test2(7) != 7)
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abort();
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if (test3(0) != 0)
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abort();
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if (test3(2) != 0)
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abort();
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if (test3(5) != 5)
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abort();
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if (test3(7) != 5)
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abort();
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if (test4(0) != 2)
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abort();
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if (test4(2) != 2)
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abort();
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if (test4(5) != 7)
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abort();
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if (test4(7) != 7)
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abort();
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if (test5(0) != 0)
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abort();
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if (test5(2) != 0)
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abort();
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if (test5(5) != 5)
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abort();
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if (test5(7) != 5)
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abort();
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if (test6(0) != 0)
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abort();
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if (test6(2) != 2)
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abort();
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if (test6(5) != 5)
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abort();
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if (test6(7) != 7)
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abort();
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return 0;
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}
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