From a87d3f964df31d4fbceb822c6d293e85c117d992 Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Wed, 14 Apr 2021 20:06:45 +0100 Subject: Check for matching CONST_VECTOR encodings [PR99929] MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit PR99929 is one of those “how did we get away with this for so long” bugs: the equality routines weren't checking whether two variable-length CONST_VECTORs had the same encoding. This meant that: { 1, 0, 0, 0, 0, 0, ... } would appear to be equal to: { 1, 0, 1, 0, 1, 0, ... } since both are represented using the elements { 1, 0 }. gcc/ PR rtl-optimization/99929 * rtl.h (same_vector_encodings_p): New function. * cse.c (exp_equiv_p): Check that CONST_VECTORs have the same encoding. * cselib.c (rtx_equal_for_cselib_1): Likewise. * jump.c (rtx_renumbered_equal_p): Likewise. * lra-constraints.c (operands_match_p): Likewise. * reload.c (operands_match_p): Likewise. * rtl.c (rtx_equal_p_cb, rtx_equal_p): Likewise. gcc/testsuite/ * gcc.target/aarch64/sve/pr99929_1.c: New file. * gcc.target/aarch64/sve/pr99929_2.c: Likewise. --- gcc/rtl.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'gcc/rtl.h') diff --git a/gcc/rtl.h b/gcc/rtl.h index a392721..398d745 100644 --- a/gcc/rtl.h +++ b/gcc/rtl.h @@ -3087,6 +3087,23 @@ vec_series_p (const_rtx x, rtx *base_out, rtx *step_out) return const_vec_series_p (x, base_out, step_out); } +/* Return true if CONST_VECTORs X and Y, which are known to have the same mode, + also have the same encoding. This means that they are equal whenever their + operands are equal. */ + +inline bool +same_vector_encodings_p (const_rtx x, const_rtx y) +{ + /* Don't be fussy about the encoding of constant-length vectors, + since XVECEXP (X, 0) and XVECEXP (Y, 0) list all the elements anyway. */ + if (poly_uint64 (CONST_VECTOR_NUNITS (x)).is_constant ()) + return true; + + return (CONST_VECTOR_NPATTERNS (x) == CONST_VECTOR_NPATTERNS (y) + && (CONST_VECTOR_NELTS_PER_PATTERN (x) + == CONST_VECTOR_NELTS_PER_PATTERN (y))); +} + /* Return the unpromoted (outer) mode of SUBREG_PROMOTED_VAR_P subreg X. */ inline scalar_int_mode -- cgit v1.1