[gcc r15-6309] middle-end/118062 - bogus lowering of vector compares

[Richard Biener via Gcc-cvs]

https://gcc.gnu.org/g:cfe1ad3c488693a10fafb39d68c8cabc6e48daa7

commit r15-6309-gcfe1ad3c488693a10fafb39d68c8cabc6e48daa7
Author: Richard Biener <rguent...@suse.de>
Date:   Tue Dec 17 11:23:02 2024 +0100

    middle-end/118062 - bogus lowering of vector compares
    
    The generic expand_vector_piecewise routine supports lowering of
    a vector operation to vector operations of smaller size.  When
    computing the extract position from the larger vector it uses the
    element size in bits of the original result vector to determine
    the number of elements in the smaller vector.  That is wrong when
    lowering a compare as the vector element size of a bool vector
    does not have to agree with that of the compare operand.  The
    following simplifies this, fixing the error.
    
            PR middle-end/118062
            * tree-vect-generic.cc (expand_vector_piecewise): Properly
            compute delta.

Diff:
---
 gcc/tree-vect-generic.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcc/tree-vect-generic.cc b/gcc/tree-vect-generic.cc
index 78f6e552cc7b..4b9cf734bdd1 100644
--- a/gcc/tree-vect-generic.cc
+++ b/gcc/tree-vect-generic.cc
@@ -292,7 +292,8 @@ expand_vector_piecewise (gimple_stmt_iterator *gsi, 
elem_op_func f,
   tree part_width = TYPE_SIZE (inner_type);
   tree index = bitsize_int (0);
   int nunits = nunits_for_known_piecewise_op (type);
-  int delta = tree_to_uhwi (part_width) / vector_element_bits (type);
+  int delta = (VECTOR_TYPE_P (inner_type)
+              ? nunits_for_known_piecewise_op (inner_type) : 1);
   int i;
   location_t loc = gimple_location (gsi_stmt (*gsi));