fold-const: Handle bitfields in native_encode_initializer [PR93121]
When working on __builtin_bit_cast that needs to handle bitfields too, I've made the following change to handle at least some bitfields in native_encode_initializer (those that have integral representative). 2020-07-20 Jakub Jelinek <jakub@redhat.com> PR libstdc++/93121 * fold-const.c (native_encode_initializer): Handle bit-fields. * gcc.dg/tree-ssa/pr93121-1.c: New test.
This commit is contained in:
Jakub Jelinek
parent
0251a7eef9
commit
83b171655d
114
gcc/fold-const.c
114
gcc/fold-const.c
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@ -8047,6 +8047,7 @@ native_encode_initializer (tree init, unsigned char *ptr, int len,
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tree field = ce->index;
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tree val = ce->value;
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HOST_WIDE_INT pos, fieldsize;
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unsigned HOST_WIDE_INT bpos = 0, epos = 0;
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if (field == NULL_TREE)
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return 0;
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@ -8066,15 +8067,122 @@ native_encode_initializer (tree init, unsigned char *ptr, int len,
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if (fieldsize == 0)
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continue;
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if (DECL_BIT_FIELD (field))
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{
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if (!tree_fits_uhwi_p (DECL_FIELD_BIT_OFFSET (field)))
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return 0;
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fieldsize = TYPE_PRECISION (TREE_TYPE (field));
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bpos = tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field));
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if (bpos % BITS_PER_UNIT)
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bpos %= BITS_PER_UNIT;
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else
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bpos = 0;
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fieldsize += bpos;
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epos = fieldsize % BITS_PER_UNIT;
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fieldsize += BITS_PER_UNIT - 1;
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fieldsize /= BITS_PER_UNIT;
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}
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if (off != -1 && pos + fieldsize <= off)
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continue;
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if (DECL_BIT_FIELD (field))
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return 0;
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if (val == NULL_TREE)
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continue;
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if (DECL_BIT_FIELD (field))
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{
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/* FIXME: Handle PDP endian. */
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if (BYTES_BIG_ENDIAN != WORDS_BIG_ENDIAN)
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return 0;
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tree repr = DECL_BIT_FIELD_REPRESENTATIVE (field);
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if (repr == NULL_TREE
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|| TREE_CODE (val) != INTEGER_CST
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|| !INTEGRAL_TYPE_P (TREE_TYPE (repr)))
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return 0;
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HOST_WIDE_INT rpos = int_byte_position (repr);
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if (rpos > pos)
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return 0;
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wide_int w = wi::to_wide (val,
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TYPE_PRECISION (TREE_TYPE (repr)));
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int diff = (TYPE_PRECISION (TREE_TYPE (repr))
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- TYPE_PRECISION (TREE_TYPE (field)));
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HOST_WIDE_INT bitoff = (pos - rpos) * BITS_PER_UNIT + bpos;
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if (!BYTES_BIG_ENDIAN)
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w = wi::lshift (w, bitoff);
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else
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w = wi::lshift (w, diff - bitoff);
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val = wide_int_to_tree (TREE_TYPE (repr), w);
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unsigned char buf[MAX_BITSIZE_MODE_ANY_INT
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/ BITS_PER_UNIT + 1];
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int l = native_encode_int (val, buf, sizeof buf, 0);
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if (l * BITS_PER_UNIT != TYPE_PRECISION (TREE_TYPE (repr)))
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return 0;
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if (ptr == NULL)
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continue;
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/* If the bitfield does not start at byte boundary, handle
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the partial byte at the start. */
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if (bpos
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&& (off == -1 || (pos >= off && len >= 1)))
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{
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if (!BYTES_BIG_ENDIAN)
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{
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int mask = (1 << bpos) - 1;
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buf[pos - rpos] &= ~mask;
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buf[pos - rpos] |= ptr[pos - o] & mask;
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}
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else
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{
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int mask = (1 << (BITS_PER_UNIT - bpos)) - 1;
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buf[pos - rpos] &= mask;
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buf[pos - rpos] |= ptr[pos - o] & ~mask;
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}
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}
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/* If the bitfield does not end at byte boundary, handle
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the partial byte at the end. */
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if (epos
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&& (off == -1
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|| pos + fieldsize <= (HOST_WIDE_INT) off + len))
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{
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if (!BYTES_BIG_ENDIAN)
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{
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int mask = (1 << epos) - 1;
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buf[pos - rpos + fieldsize - 1] &= mask;
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buf[pos - rpos + fieldsize - 1]
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|= ptr[pos + fieldsize - 1 - o] & ~mask;
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}
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else
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{
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int mask = (1 << (BITS_PER_UNIT - epos)) - 1;
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buf[pos - rpos + fieldsize - 1] &= ~mask;
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buf[pos - rpos + fieldsize - 1]
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|= ptr[pos + fieldsize - 1 - o] & mask;
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}
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}
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if (off == -1
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|| (pos >= off
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&& (pos + fieldsize <= (HOST_WIDE_INT) off + len)))
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memcpy (ptr + pos - o, buf + (pos - rpos), fieldsize);
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else
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{
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/* Partial overlap. */
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HOST_WIDE_INT fsz = fieldsize;
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if (pos < off)
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{
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fsz -= (off - pos);
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pos = off;
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}
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if (pos + fsz > (HOST_WIDE_INT) off + len)
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fsz = (HOST_WIDE_INT) off + len - pos;
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memcpy (ptr + pos - off, buf + (pos - rpos), fsz);
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}
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continue;
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}
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if (off == -1
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|| (pos >= off
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&& (pos + fieldsize <= (HOST_WIDE_INT) off + len)))
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@ -0,0 +1,56 @@
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/* PR libstdc++/93121 */
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/* { dg-do compile { target { ilp32 || lp64 } } } */
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/* { dg-options "-O2 -fdump-tree-optimized" } */
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union U { int a[3]; short c[6]; struct S { int d; int a : 2; int f : 1; int b : 24; int c : 5; int e; } b; };
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const union U u = { .b = { 0x7efa3412, 3, 0, 0x50eca8, 0xb, 0x1eeffeed } };
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const union U v = { .b = { 0x7efa3412, 1, 1, 0x7feedb, 0x5, 0x1eeffeed } };
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union W { struct T { long long int a, b : 11, c : 3, d : 37, e : 1, f : 10, g : 2, h; } a; int b[6]; short c[12]; long long d[3]; };
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const union W w = { .a = { 0x0feedbacdeadbeefLL, -1011, 2, -0xbacdeadbeLL, -1, 721, 1, 0x0feedbacdeadbeefLL } };
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int a, b, c, d, e, f, g, h, i, j, k, l;
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long long m;
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void
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foo ()
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{
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a = u.a[1];
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b = v.a[1];
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c = u.c[2];
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d = u.c[3];
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e = v.c[2];
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f = v.c[3];
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g = w.b[2];
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h = w.b[3];
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i = w.c[4];
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j = w.c[5];
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k = w.c[6];
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l = w.c[7];
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m = w.d[1];
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}
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/* { dg-final { scan-tree-dump-times "a = 1518822723;" 1 "optimized" { target le } } } */
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/* { dg-final { scan-tree-dump-times "b = 738162397;" 1 "optimized" { target le } } } */
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/* { dg-final { scan-tree-dump-times "c = 25923;" 1 "optimized" { target le } } } */
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/* { dg-final { scan-tree-dump-times "d = 23175;" 1 "optimized" { target le } } } */
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/* { dg-final { scan-tree-dump-times "e = 30429;" 1 "optimized" { target le } } } */
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/* { dg-final { scan-tree-dump-times "f = 11263;" 1 "optimized" { target le } } } */
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/* { dg-final { scan-tree-dump-times "g = 1418761229;" 1 "optimized" { target le } } } */
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/* { dg-final { scan-tree-dump-times "h = 1830622408;" 1 "optimized" { target le } } } */
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/* { dg-final { scan-tree-dump-times "i = -27635;" 1 "optimized" { target le } } } */
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/* { dg-final { scan-tree-dump-times "j = 21648;" 1 "optimized" { target le } } } */
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/* { dg-final { scan-tree-dump-times "k = 5320;" 1 "optimized" { target le } } } */
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/* { dg-final { scan-tree-dump-times "l = 27933;" 1 "optimized" { target le } } } */
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/* { dg-final { scan-tree-dump-times "m = 7862463375103529997;" 1 "optimized" { target le } } } */
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/* { dg-final { scan-tree-dump-times "a = -904030965;" 1 "optimized" { target be } } } */
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/* { dg-final { scan-tree-dump-times "b = 1878907749;" 1 "optimized" { target be } } } */
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/* { dg-final { scan-tree-dump-times "c = -13795;" 1 "optimized" { target be } } } */
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/* { dg-final { scan-tree-dump-times "d = -27381;" 1 "optimized" { target be } } } */
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/* { dg-final { scan-tree-dump-times "e = 28669;" 1 "optimized" { target be } } } */
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/* { dg-final { scan-tree-dump-times "f = -9371;" 1 "optimized" { target be } } } */
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/* { dg-final { scan-tree-dump-times "g = -2119529884;" 1 "optimized" { target be } } } */
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/* { dg-final { scan-tree-dump-times "h = 709385029;" 1 "optimized" { target be } } } */
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/* { dg-final { scan-tree-dump-times "i = -32342;" 1 "optimized" { target be } } } */
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/* { dg-final { scan-tree-dump-times "j = -30108;" 1 "optimized" { target be } } } */
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/* { dg-final { scan-tree-dump-times "k = 10824;" 1 "optimized" { target be } } } */
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/* { dg-final { scan-tree-dump-times "l = 23365;" 1 "optimized" { target be } } } */
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/* { dg-final { scan-tree-dump-times "m = -9103311533965288635;" 1 "optimized" { target be } } } */
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