fold-const.c (fold_binary): Fold BIT_AND_EXPR's with a pointer operand.
gcc/ fold-const.c (fold_binary): Fold BIT_AND_EXPR's with a pointer operand. (get_pointer_modulus_and_residue): New function. gcc/testsuite/ gcc.dg/fold-bitand-1.c: New test. gcc.dg/fold-bitand-2.c: New test. gcc.dg/fold-bitand-3.c: New test. gcc.dg/fold-bitand-4.c: New test. From-SVN: r128701
This commit is contained in:
Ollie Wild
Ollie Wild
parent
50b73fcde4
commit
e5901cad3f
@ -1,3 +1,8 @@
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2007-09-23 Ollie Wild <aaw@google.com>
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fold-const.c (fold_binary): Fold BIT_AND_EXPR's with a pointer operand.
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(get_pointer_modulus_and_residue): New function.
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2007-09-23 Richard Sandiford <rsandifo@nildram.co.uk>
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* config/mips/mips.c (build_mips16_call_stub): On 64-bit targets,
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108
gcc/fold-const.c
108
gcc/fold-const.c
@ -9384,6 +9384,97 @@ fold_mult_zconjz (tree type, tree expr)
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}
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/* Subroutine of fold_binary. If P is the value of EXPR, computes
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power-of-two M and (arbitrary) N such that M divides (P-N). This condition
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guarantees that P and N have the same least significant log2(M) bits.
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N is not otherwise constrained. In particular, N is not normalized to
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0 <= N < M as is common. In general, the precise value of P is unknown.
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M is chosen as large as possible such that constant N can be determined.
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Returns M and sets *RESIDUE to N. */
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static unsigned HOST_WIDE_INT
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get_pointer_modulus_and_residue (tree expr, unsigned HOST_WIDE_INT *residue)
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{
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enum tree_code code;
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*residue = 0;
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code = TREE_CODE (expr);
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if (code == ADDR_EXPR)
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{
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expr = TREE_OPERAND (expr, 0);
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if (handled_component_p (expr))
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{
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HOST_WIDE_INT bitsize, bitpos;
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tree offset;
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enum machine_mode mode;
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int unsignedp, volatilep;
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expr = get_inner_reference (expr, &bitsize, &bitpos, &offset,
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&mode, &unsignedp, &volatilep, false);
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*residue = bitpos / BITS_PER_UNIT;
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if (offset)
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{
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if (TREE_CODE (offset) == INTEGER_CST)
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*residue += TREE_INT_CST_LOW (offset);
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else
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/* We don't handle more complicated offset expressions. */
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return 1;
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}
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}
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if (DECL_P (expr))
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return DECL_ALIGN_UNIT (expr);
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}
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else if (code == POINTER_PLUS_EXPR)
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{
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tree op0, op1;
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unsigned HOST_WIDE_INT modulus;
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enum tree_code inner_code;
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op0 = TREE_OPERAND (expr, 0);
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STRIP_NOPS (op0);
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modulus = get_pointer_modulus_and_residue (op0, residue);
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op1 = TREE_OPERAND (expr, 1);
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STRIP_NOPS (op1);
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inner_code = TREE_CODE (op1);
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if (inner_code == INTEGER_CST)
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{
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*residue += TREE_INT_CST_LOW (op1);
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return modulus;
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}
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else if (inner_code == MULT_EXPR)
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{
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op1 = TREE_OPERAND (op1, 1);
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if (TREE_CODE (op1) == INTEGER_CST)
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{
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unsigned HOST_WIDE_INT align;
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/* Compute the greatest power-of-2 divisor of op1. */
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align = TREE_INT_CST_LOW (op1);
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align &= -align;
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/* If align is non-zero and less than *modulus, replace
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*modulus with align., If align is 0, then either op1 is 0
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or the greatest power-of-2 divisor of op1 doesn't fit in an
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unsigned HOST_WIDE_INT. In either case, no additional
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constraint is imposed. */
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if (align)
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modulus = MIN (modulus, align);
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return modulus;
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}
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}
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}
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/* If we get here, we were unable to determine anything useful about the
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expression. */
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return 1;
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}
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/* Fold a binary expression of code CODE and type TYPE with operands
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OP0 and OP1. Return the folded expression if folding is
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successful. Otherwise, return NULL_TREE. */
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@ -10915,6 +11006,23 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
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TREE_OPERAND (arg1, 0)));
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}
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/* If arg0 is derived from the address of an object or function, we may
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be able to fold this expression using the object or function's
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alignment. */
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if (POINTER_TYPE_P (TREE_TYPE (arg0)) && host_integerp (arg1, 1))
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{
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unsigned HOST_WIDE_INT modulus, residue;
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unsigned HOST_WIDE_INT low = TREE_INT_CST_LOW (arg1);
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modulus = get_pointer_modulus_and_residue (arg0, &residue);
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/* This works because modulus is a power of 2. If this weren't the
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case, we'd have to replace it by its greatest power-of-2
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divisor: modulus & -modulus. */
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if (low < modulus)
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return build_int_cst (type, residue & low);
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}
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goto associate;
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case RDIV_EXPR:
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@ -1,3 +1,10 @@
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2007-09-23 Ollie Wild <aaw@google.com>
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gcc.dg/fold-bitand-1.c: New test.
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gcc.dg/fold-bitand-2.c: New test.
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gcc.dg/fold-bitand-3.c: New test.
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gcc.dg/fold-bitand-4.c: New test.
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2007-09-23 Richard Sandiford <rsandifo@nildram.co.uk>
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* gcc.target/mips/gcc-have-sync-compare-and-swap-1.c: Don't expect
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34
gcc/testsuite/gcc.dg/fold-bitand-1.c
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34
gcc/testsuite/gcc.dg/fold-bitand-1.c
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@ -0,0 +1,34 @@
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/* { dg-do compile } */
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/* { dg-options "-fdump-tree-original" } */
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char c1 __attribute__ ((aligned (1)));
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char c2 __attribute__ ((aligned (2)));
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char c4 __attribute__ ((aligned (4)));
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char c8 __attribute__ ((aligned (8)));
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unsigned f1(void)
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{
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return 3 & (__SIZE_TYPE__)&c1;
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}
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unsigned f2(void)
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{
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return 3 & (__SIZE_TYPE__)&c2;
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}
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unsigned f3(void)
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{
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return 3 & (__SIZE_TYPE__)&c4;
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}
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unsigned f4(void)
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{
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return 3 & (__SIZE_TYPE__)&c8;
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}
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/* { dg-final { scan-tree-dump-times "\&c1 \& 3" 1 "original" } } */
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/* { dg-final { scan-tree-dump-times "\&c2 \& 3" 1 "original" } } */
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/* { dg-final { scan-tree-dump-times "\&c4 \& 3" 0 "original" } } */
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/* { dg-final { scan-tree-dump-times "\&c8 \& 3" 0 "original" } } */
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/* { dg-final { scan-tree-dump-times "return 0" 2 "original" } } */
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/* { dg-final { cleanup-tree-dump "original" } } */
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42
gcc/testsuite/gcc.dg/fold-bitand-2.c
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42
gcc/testsuite/gcc.dg/fold-bitand-2.c
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@ -0,0 +1,42 @@
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/* { dg-do compile } */
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/* { dg-options "-fdump-tree-original" } */
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struct {
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char c1;
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char c2;
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char c3;
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char c4;
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} s __attribute__ ((aligned (4)));
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unsigned f1 (void)
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{
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return 3 & (__SIZE_TYPE__)&s.c1;
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}
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unsigned f2 (void)
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{
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return 3 & (__SIZE_TYPE__)&s.c2;
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}
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unsigned f3 (void)
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{
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return 3 & (__SIZE_TYPE__)&s.c3;
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}
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unsigned f4 (void)
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{
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return 3 & (__SIZE_TYPE__)&s.c4;
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}
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unsigned f5 (void)
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{
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return 4 & (__SIZE_TYPE__)&s.c1;
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}
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/* { dg-final { scan-tree-dump-times "\& 3" 0 "original" } } */
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/* { dg-final { scan-tree-dump-times "\& 4" 1 "original" } } */
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/* { dg-final { scan-tree-dump-times "return 0" 1 "original" } } */
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/* { dg-final { scan-tree-dump-times "return 1" 1 "original" } } */
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/* { dg-final { scan-tree-dump-times "return 2" 1 "original" } } */
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/* { dg-final { scan-tree-dump-times "return 3" 1 "original" } } */
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/* { dg-final { cleanup-tree-dump "original" } } */
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25
gcc/testsuite/gcc.dg/fold-bitand-3.c
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25
gcc/testsuite/gcc.dg/fold-bitand-3.c
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@ -0,0 +1,25 @@
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/* { dg-do compile } */
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/* { dg-options "-fdump-tree-original" } */
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char c[4] __attribute__ ((aligned (4)));
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struct S {
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char c1;
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char c2;
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char c3;
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char c4;
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};
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int f1 (void)
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{
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return 3 & (__SIZE_TYPE__)&c[1];
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}
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int f2 (void)
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{
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return 3 & (__SIZE_TYPE__)&((struct S *)&c)->c2;
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}
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/* { dg-final { scan-tree-dump-times "\& 3" 0 "original" } } */
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/* { dg-final { scan-tree-dump-times "return 1" 2 "original" } } */
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/* { dg-final { cleanup-tree-dump "original" } } */
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44
gcc/testsuite/gcc.dg/fold-bitand-4.c
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44
gcc/testsuite/gcc.dg/fold-bitand-4.c
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/* { dg-do compile } */
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/* { dg-options "-fdump-tree-original" } */
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typedef char char4[4] __attribute__ ((aligned (4)));
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char4 c4[4] __attribute__ ((aligned (16)));
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typedef char char16[16] __attribute__ ((aligned (16)));
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char16 c16[4] __attribute__ ((aligned (4)));
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int f1 (void)
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{
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/* 12 */
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return 15 & (__SIZE_TYPE__)&c4[3];
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}
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int f2 (int i)
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{
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/* Indeterminate */
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return 15 & (__SIZE_TYPE__)&c4[i];
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}
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int f3 (int i)
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{
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/* 0 */
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return 3 & (__SIZE_TYPE__)&c4[i];
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}
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int f4 (int i)
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{
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/* Indeterminate */
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return 7 & (__SIZE_TYPE__)&c16[i];
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}
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int f5 (int i)
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{
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/* 0 */
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return 3 & (__SIZE_TYPE__)&c16[i];
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}
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/* { dg-final { scan-tree-dump-times "return 12" 1 "original" } } */
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/* { dg-final { scan-tree-dump-times "\& 15" 1 "original" } } */
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/* { dg-final { scan-tree-dump-times "return 0" 2 "original" } } */
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/* { dg-final { scan-tree-dump-times "\& 7" 1 "original" } } */
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/* { dg-final { cleanup-tree-dump "original" } } */
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