[Bug target/39327] New: Incorrect addsub patterns in sse.md

[hjl dot tools at gmail dot com]

SSE addsubpX does

Adds odd-numbered single-precision floating-point values of the first source
operand
(second operand) with the corresponding single-precision floating-point values
from
the second source operand (third operand); stores the result in the
odd-numbered
values of the destination operand (first operand). Subtracts the even-numbered
single-precision floating-point values from the second source operand from the
corresponding single-precision floating values in the first source operand;
stores the
result into the even-numbered values of the destination operand.

They are implemented as

(define_insn "sse3_addsubv4sf3"
  [(set (match_operand:V4SF 0 "register_operand" "=x")
        (vec_merge:V4SF
          (plus:V4SF
            (match_operand:V4SF 1 "register_operand" "0")
            (match_operand:V4SF 2 "nonimmediate_operand" "xm"))
          (minus:V4SF (match_dup 1) (match_dup 2))
          (const_int 5)))]
  "TARGET_SSE3"
  "addsubps\t{%2, %0|%0, %2}"
  [(set_attr "type" "sseadd")
   (set_attr "prefix_rep" "1")
   (set_attr "mode" "V4SF")])

We have

@item (vec_merge:@var{m} @var{vec1} @var{vec2} @var{items})
This describes a merge operation between two vectors.  The result is a vector
of mode @var{m}; its elements are selected from either @var{vec1} or
@var{vec2}.  Which elements are selected is described by @var{items}, which
is a bit mask represented by a @code{const_int}; a zero bit indicates the
corresponding element in the result vector is taken from @var{vec2} while
a set bit indicates it is taken from @var{vec1}.

Is item bit reversed?


-- 
           Summary: Incorrect addsub patterns in sse.md
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: hjl dot tools at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39327