On Sat, 18 Jul 2020, Jakub Jelinek wrote:
> Hi!
>
> 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).
>
> Bootstrapped/regtested on {x86_64,i686,powerpc64{,le}}-linux, ok for trunk?
OK.
Thanks,
Richard.
> 2020-07-18 Jakub Jelinek <ja...@redhat.com>
>
> PR libstdc++/93121
> * fold-const.c (native_encode_initializer): Handle bit-fields.
>
> * gcc.dg/tree-ssa/pr93121-1.c: New test.
>
> --- gcc/fold-const.c.jj 2020-06-24 10:39:48.995469213 +0200
> +++ gcc/fold-const.c 2020-07-17 13:51:53.181392890 +0200
> @@ -8047,6 +8047,7 @@ native_encode_initializer (tree init, un
> tree field = ce->index;
> tree val = ce->value;
> HOST_WIDE_INT pos, fieldsize;
> + unsigned HOST_WIDE_INT bpos = 0, epos = 0;
>
> if (field == NULL_TREE)
> return 0;
> @@ -8066,15 +8067,122 @@ native_encode_initializer (tree init, un
> if (fieldsize == 0)
> continue;
>
> + if (DECL_BIT_FIELD (field))
> + {
> + if (!tree_fits_uhwi_p (DECL_FIELD_BIT_OFFSET (field)))
> + return 0;
> + fieldsize = TYPE_PRECISION (TREE_TYPE (field));
> + bpos = tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field));
> + if (bpos % BITS_PER_UNIT)
> + bpos %= BITS_PER_UNIT;
> + else
> + bpos = 0;
> + fieldsize += bpos;
> + epos = fieldsize % BITS_PER_UNIT;
> + fieldsize += BITS_PER_UNIT - 1;
> + fieldsize /= BITS_PER_UNIT;
> + }
> +
> if (off != -1 && pos + fieldsize <= off)
> continue;
>
> - if (DECL_BIT_FIELD (field))
> - return 0;
> -
> if (val == NULL_TREE)
> continue;
>
> + if (DECL_BIT_FIELD (field))
> + {
> + /* FIXME: Handle PDP endian. */
> + if (BYTES_BIG_ENDIAN != WORDS_BIG_ENDIAN)
> + return 0;
> +
> + tree repr = DECL_BIT_FIELD_REPRESENTATIVE (field);
> + if (repr == NULL_TREE
> + || TREE_CODE (val) != INTEGER_CST
> + || !INTEGRAL_TYPE_P (TREE_TYPE (repr)))
> + return 0;
> +
> + HOST_WIDE_INT rpos = int_byte_position (repr);
> + if (rpos > pos)
> + return 0;
> + wide_int w = wi::to_wide (val,
> + TYPE_PRECISION (TREE_TYPE (repr)));
> + int diff = (TYPE_PRECISION (TREE_TYPE (repr))
> + - TYPE_PRECISION (TREE_TYPE (field)));
> + HOST_WIDE_INT bitoff = (pos - rpos) * BITS_PER_UNIT + bpos;
> + if (!BYTES_BIG_ENDIAN)
> + w = wi::lshift (w, bitoff);
> + else
> + w = wi::lshift (w, diff - bitoff);
> + val = wide_int_to_tree (TREE_TYPE (repr), w);
> +
> + unsigned char buf[MAX_BITSIZE_MODE_ANY_INT
> + / BITS_PER_UNIT + 1];
> + int l = native_encode_int (val, buf, sizeof buf, 0);
> + if (l * BITS_PER_UNIT != TYPE_PRECISION (TREE_TYPE (repr)))
> + return 0;
> +
> + if (ptr == NULL)
> + continue;
> +
> + /* If the bitfield does not start at byte boundary, handle
> + the partial byte at the start. */
> + if (bpos
> + && (off == -1 || (pos >= off && len >= 1)))
> + {
> + if (!BYTES_BIG_ENDIAN)
> + {
> + int mask = (1 << bpos) - 1;
> + buf[pos - rpos] &= ~mask;
> + buf[pos - rpos] |= ptr[pos - o] & mask;
> + }
> + else
> + {
> + int mask = (1 << (BITS_PER_UNIT - bpos)) - 1;
> + buf[pos - rpos] &= mask;
> + buf[pos - rpos] |= ptr[pos - o] & ~mask;
> + }
> + }
> + /* If the bitfield does not end at byte boundary, handle
> + the partial byte at the end. */
> + if (epos
> + && (off == -1
> + || pos + fieldsize <= (HOST_WIDE_INT) off + len))
> + {
> + if (!BYTES_BIG_ENDIAN)
> + {
> + int mask = (1 << epos) - 1;
> + buf[pos - rpos + fieldsize - 1] &= mask;
> + buf[pos - rpos + fieldsize - 1]
> + |= ptr[pos + fieldsize - 1 - o] & ~mask;
> + }
> + else
> + {
> + int mask = (1 << (BITS_PER_UNIT - epos)) - 1;
> + buf[pos - rpos + fieldsize - 1] &= ~mask;
> + buf[pos - rpos + fieldsize - 1]
> + |= ptr[pos + fieldsize - 1 - o] & mask;
> + }
> + }
> + if (off == -1
> + || (pos >= off
> + && (pos + fieldsize <= (HOST_WIDE_INT) off + len)))
> + memcpy (ptr + pos - o, buf + (pos - rpos), fieldsize);
> + else
> + {
> + /* Partial overlap. */
> + HOST_WIDE_INT fsz = fieldsize;
> + if (pos < off)
> + {
> + fsz -= (off - pos);
> + pos = off;
> + }
> + if (pos + fsz > (HOST_WIDE_INT) off + len)
> + fsz = (HOST_WIDE_INT) off + len - pos;
> + memcpy (ptr + pos - off, buf + (pos - rpos), fsz);
> + }
> + continue;
> + }
> +
> if (off == -1
> || (pos >= off
> && (pos + fieldsize <= (HOST_WIDE_INT) off + len)))
> --- gcc/testsuite/gcc.dg/tree-ssa/pr93121-1.c.jj 2020-07-17
> 13:33:47.106539060 +0200
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr93121-1.c 2020-07-17 13:54:46.786813165
> +0200
> @@ -0,0 +1,56 @@
> +/* PR libstdc++/93121 */
> +/* { dg-do compile { target { ilp32 || lp64 } } } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +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; };
> +const union U u = { .b = { 0x7efa3412, 3, 0, 0x50eca8, 0xb, 0x1eeffeed } };
> +const union U v = { .b = { 0x7efa3412, 1, 1, 0x7feedb, 0x5, 0x1eeffeed } };
> +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]; };
> +const union W w = { .a = { 0x0feedbacdeadbeefLL, -1011, 2, -0xbacdeadbeLL,
> -1, 721, 1, 0x0feedbacdeadbeefLL } };
> +int a, b, c, d, e, f, g, h, i, j, k, l;
> +long long m;
> +
> +void
> +foo ()
> +{
> + a = u.a[1];
> + b = v.a[1];
> + c = u.c[2];
> + d = u.c[3];
> + e = v.c[2];
> + f = v.c[3];
> + g = w.b[2];
> + h = w.b[3];
> + i = w.c[4];
> + j = w.c[5];
> + k = w.c[6];
> + l = w.c[7];
> + m = w.d[1];
> +}
> +
> +/* { dg-final { scan-tree-dump-times "a = 1518822723;" 1 "optimized" {
> target le } } } */
> +/* { dg-final { scan-tree-dump-times "b = 738162397;" 1 "optimized" { target
> le } } } */
> +/* { dg-final { scan-tree-dump-times "c = 25923;" 1 "optimized" { target le
> } } } */
> +/* { dg-final { scan-tree-dump-times "d = 23175;" 1 "optimized" { target le
> } } } */
> +/* { dg-final { scan-tree-dump-times "e = 30429;" 1 "optimized" { target le
> } } } */
> +/* { dg-final { scan-tree-dump-times "f = 11263;" 1 "optimized" { target le
> } } } */
> +/* { dg-final { scan-tree-dump-times "g = 1418761229;" 1 "optimized" {
> target le } } } */
> +/* { dg-final { scan-tree-dump-times "h = 1830622408;" 1 "optimized" {
> target le } } } */
> +/* { dg-final { scan-tree-dump-times "i = -27635;" 1 "optimized" { target le
> } } } */
> +/* { dg-final { scan-tree-dump-times "j = 21648;" 1 "optimized" { target le
> } } } */
> +/* { dg-final { scan-tree-dump-times "k = 5320;" 1 "optimized" { target le }
> } } */
> +/* { dg-final { scan-tree-dump-times "l = 27933;" 1 "optimized" { target le
> } } } */
> +/* { dg-final { scan-tree-dump-times "m = 7862463375103529997;" 1
> "optimized" { target le } } } */
> +/* { dg-final { scan-tree-dump-times "a = -904030965;" 1 "optimized" {
> target be } } } */
> +/* { dg-final { scan-tree-dump-times "b = 1878907749;" 1 "optimized" {
> target be } } } */
> +/* { dg-final { scan-tree-dump-times "c = -13795;" 1 "optimized" { target be
> } } } */
> +/* { dg-final { scan-tree-dump-times "d = -27381;" 1 "optimized" { target be
> } } } */
> +/* { dg-final { scan-tree-dump-times "e = 28669;" 1 "optimized" { target be
> } } } */
> +/* { dg-final { scan-tree-dump-times "f = -9371;" 1 "optimized" { target be
> } } } */
> +/* { dg-final { scan-tree-dump-times "g = -2119529884;" 1 "optimized" {
> target be } } } */
> +/* { dg-final { scan-tree-dump-times "h = 709385029;" 1 "optimized" { target
> be } } } */
> +/* { dg-final { scan-tree-dump-times "i = -32342;" 1 "optimized" { target be
> } } } */
> +/* { dg-final { scan-tree-dump-times "j = -30108;" 1 "optimized" { target be
> } } } */
> +/* { dg-final { scan-tree-dump-times "k = 10824;" 1 "optimized" { target be
> } } } */
> +/* { dg-final { scan-tree-dump-times "l = 23365;" 1 "optimized" { target be
> } } } */
> +/* { dg-final { scan-tree-dump-times "m = -9103311533965288635;" 1
> "optimized" { target be } } } */
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
