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| author | Jakub Jelinek <jakub@redhat.com> | 2024-12-03 11:16:37 +0100 |
|---|---|---|
| committer | Jakub Jelinek <jakub@gcc.gnu.org> | 2024-12-03 11:16:37 +0100 |
| commit | 0b89341f124eadc689682d01193309225adfec23 (patch) | |
| tree | b0092d41bb651645edca37abe8ff54fefcbd8e5e | |
| parent | 3d72e50caebf232fdd7f70613616ca4fd4fb472b (diff) | |
| download | gcc-0b89341f124eadc689682d01193309225adfec23.zip gcc-0b89341f124eadc689682d01193309225adfec23.tar.gz gcc-0b89341f124eadc689682d01193309225adfec23.tar.bz2 | |
bitintlower: Fix up ?ROTATE_EXPR lowering [PR117847]
In the ?ROTATE_EXPR lowering I forgot to handle rotation by 0 correctly.
INTEGER_CST 0 is very unlikely, it would be probably folded away, but
a non-constant count can't use just p - n because then the shift count
is out of bounds for zero.
In the FE I use n == 0 ? x : (x << n) | (x >> (p - n)) but bitintlower
here isn't prepared at this point to have bb split and am not sure if
using COND_EXPR is a good idea either, so the patch uses (p - n) % p.
Perhaps I should just disable lowering the rotate in the FE for the
non-mode precision BITINT_TYPEs too.
2024-12-03 Jakub Jelinek <jakub@redhat.com>
PR middle-end/117847
* gimple-lower-bitint.cc (gimple_lower_bitint) <case LROTATE_EXPR>:
Use m = (p - n) % p instead of m = p - n for the other shift count.
* gcc.dg/torture/bitint-75.c: New test.
| -rw-r--r-- | gcc/gimple-lower-bitint.cc | 13 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/torture/bitint-75.c | 27 |
2 files changed, 38 insertions, 2 deletions
diff --git a/gcc/gimple-lower-bitint.cc b/gcc/gimple-lower-bitint.cc index 1b7c2f4..7fa679b 100644 --- a/gcc/gimple-lower-bitint.cc +++ b/gcc/gimple-lower-bitint.cc @@ -6233,11 +6233,20 @@ gimple_lower_bitint (void) tree p = build_int_cst (TREE_TYPE (n), TYPE_PRECISION (type)); if (TREE_CODE (n) == INTEGER_CST) - m = fold_build2 (MINUS_EXPR, TREE_TYPE (n), p, n); + { + if (integer_zerop (n)) + m = n; + else + m = fold_build2 (MINUS_EXPR, TREE_TYPE (n), p, n); + } else { + tree tem = make_ssa_name (TREE_TYPE (n)); + g = gimple_build_assign (tem, MINUS_EXPR, p, n); + gsi_insert_before (&gsi, g, GSI_SAME_STMT); + gimple_set_location (g, loc); m = make_ssa_name (TREE_TYPE (n)); - g = gimple_build_assign (m, MINUS_EXPR, p, n); + g = gimple_build_assign (m, TRUNC_MOD_EXPR, tem, p); gsi_insert_before (&gsi, g, GSI_SAME_STMT); gimple_set_location (g, loc); } diff --git a/gcc/testsuite/gcc.dg/torture/bitint-75.c b/gcc/testsuite/gcc.dg/torture/bitint-75.c new file mode 100644 index 0000000..365e6d6 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/bitint-75.c @@ -0,0 +1,27 @@ +/* PR middle-end/117847 */ +/* { dg-do run { target bitint } } */ +/* { dg-options "-std=c23" } */ +/* { dg-skip-if "" { ! run_expensive_tests } { "*" } { "-O0" "-O2" } } */ +/* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */ + +#if __BITINT_MAXWIDTH__ >= 512 +typedef unsigned _BitInt(512) B; + +__attribute__((noipa)) B +foo (B a, int r) +{ + B b = __builtin_stdc_rotate_left (a, r); + return b; +} +#endif + +int +main () +{ +#if __BITINT_MAXWIDTH__ >= 512 + B a = 0x4ad4fdecc8717d7c6f8b1afb82fdb742477ef2ab34057d1dcc79ba30c38a352dea3253c8c25126d98da02213ad54b90d2998f947941ea4b45e71c61dc1fe3192uwb; + B x = foo (a, 0); + if (x != a) + __builtin_abort (); +#endif +} |