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From: Jakub Jelinek <jakub@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-5529] i386: Fix up ix86_convert_const_wide_int_to_broadcast [PR108599] Date: Tue, 31 Jan 2023 09:12:52 +0000 (GMT) [thread overview] Message-ID: <20230131091252.A77873858D28@sourceware.org> (raw) https://gcc.gnu.org/g:963315a922e228c4f6853826666151fc540f111a commit r13-5529-g963315a922e228c4f6853826666151fc540f111a Author: Jakub Jelinek <jakub@redhat.com> Date: Tue Jan 31 10:12:19 2023 +0100 i386: Fix up ix86_convert_const_wide_int_to_broadcast [PR108599] The following testcase is miscompiled. The problem is that during RTL DSE we see a V4DI register is being loaded { 16, 16, 0, 0 } value and DSE mostly works in terms of scalar modes, so it calls movoi to set an OImode REG to (const_wide_int 0x100000000000000010) and ix86_convert_const_wide_int_to_broadcast thinks it can compute that value by broadcasting DImode 0x10. While it is true that for TImode result the broadcast could be used, for OImode/XImode it can't be, because all but the lowest 2 HOST_WIDE_INTs aren't present (so are 0 or -1 depending on sign), not 0x10 in this case. The function checks if the least significant HOST_WIDE_INT elt of the CONST_WIDE_INT is broadcastable from QI/HI/SI/DImode and then /* Check if OP can be broadcasted from VAL. */ for (int i = 1; i < CONST_WIDE_INT_NUNITS (op); i++) if (val != CONST_WIDE_INT_ELT (op, i)) return nullptr; That is needed of course, but nothing checks that CONST_WIDE_INT_NUNITS (op) isn't too small for the mode in question. I think if op would be 0 or -1, it ought to be never CONST_WIDE_INT, but CONST_INT and so we can just punt whenever the number of CONST_WIDE_INT elts is not the expected one. 2023-01-31 Jakub Jelinek <jakub@redhat.com> PR target/108599 * config/i386/i386-expand.cc (ix86_convert_const_wide_int_to_broadcast): Return nullptr if CONST_WIDE_INT_NUNITS (op) times HOST_BITS_PER_WIDE_INT isn't equal to bitsize of mode. * gcc.target/i386/avx2-pr108599.c: New test. Diff: --- gcc/config/i386/i386-expand.cc | 4 +++- gcc/testsuite/gcc.target/i386/avx2-pr108599.c | 32 +++++++++++++++++++++++++++ 2 files changed, 35 insertions(+), 1 deletion(-) diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc index e2e2d28bb47..e59c7b0150f 100644 --- a/gcc/config/i386/i386-expand.cc +++ b/gcc/config/i386/i386-expand.cc @@ -291,7 +291,9 @@ ix86_convert_const_wide_int_to_broadcast (machine_mode mode, rtx op) broadcast only if vector broadcast is available. */ if (!TARGET_AVX || !CONST_WIDE_INT_P (op) - || standard_sse_constant_p (op, mode)) + || standard_sse_constant_p (op, mode) + || (CONST_WIDE_INT_NUNITS (op) * HOST_BITS_PER_WIDE_INT + != GET_MODE_BITSIZE (mode))) return nullptr; HOST_WIDE_INT val = CONST_WIDE_INT_ELT (op, 0); diff --git a/gcc/testsuite/gcc.target/i386/avx2-pr108599.c b/gcc/testsuite/gcc.target/i386/avx2-pr108599.c new file mode 100644 index 00000000000..d5ddab7609f --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/avx2-pr108599.c @@ -0,0 +1,32 @@ +/* PR target/108599 */ +/* { dg-do run { target avx2 } } */ +/* { dg-options "-O2 -mavx2 -mtune=skylake-avx512" } */ + +#include "avx2-check.h" + +struct S { unsigned long long a, b, c, d; }; + +__attribute__((noipa)) void +foo (unsigned long long x, unsigned long long y, + unsigned long long z, unsigned long long w, const struct S s) +{ + if (s.a != x || s.b != y || s.c != z || s.d != w) + abort (); +} + +typedef unsigned long long V __attribute__((may_alias, vector_size (4 * sizeof (unsigned long long)))); + +static void +avx2_test (void) +{ + { + struct S s; + *(V *)&s = (V) { 16, 0, 0, 0 }; + foo (16, 0, 0, 0, s); + } + { + struct S s; + *(V *)&s = (V) { 16, 16, 0, 0 }; + foo (16, 16, 0, 0, s); + } +}
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