[Bug tree-optimization/92819] New: [10 Regression] Worse code generated on avx2 due to simplify_vector_constructor

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92819

            Bug ID: 92819
           Summary: [10 Regression] Worse code generated on avx2 due to
                    simplify_vector_constructor
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
                CC: asolokha at gmx dot com, jakub at gcc dot gnu.org,
                    marxin at gcc dot gnu.org, rguenth at gcc dot gnu.org
        Depends on: 92803
  Target Milestone: ---
              Host: x86_64-linux-gnu

+++ This bug was initially created as a clone of Bug #92803 +++

For

/* { dg-do compile } */
/* { dg-options "-O2 -mavx2" } */

typedef double v4df __attribute__((vector_size (32)));
typedef double v2df __attribute__((vector_size (16)));
typedef short v16hi __attribute__((vector_size (32)));
typedef short v8hi __attribute__((vector_size (16)));

v2df
foo (v4df x, double *p)
{
  return (v2df) { x[1], *p };
}

v2df
bar (v4df x, double *p)
{
  return (v2df) { x[0], *p };
}

v2df
baz (v2df x, double *p)
{
  return (v2df) { x[1], *p };
}

v2df
qux (v2df x, double *p)
{
  return (v2df) { x[0], *p };
}

v2df
corge (v4df x, double *p, v2df y)
{
  return (v2df) { x[3], *p };
}

generated code differences of gcc 9 and current trunk are:

@@ -6,8 +6,9 @@
 foo:
 .LFB0:
        .cfi_startproc
-       vunpckhpd       %xmm0, %xmm0, %xmm0
-       vmovhpd (%rdi), %xmm0, %xmm0
+       vbroadcastsd    (%rdi), %ymm1
+       vinsertf128     $1, %xmm1, %ymm0, %ymm0
+       vpermpd $77, %ymm0, %ymm0
        ret
        .cfi_endproc
 .LFE0:
@@ -18,7 +19,9 @@ foo:
 bar:
 .LFB1:
        .cfi_startproc
-       vmovhpd (%rdi), %xmm0, %xmm0
+       vbroadcastsd    (%rdi), %ymm1
+       vinsertf128     $1, %xmm1, %ymm0, %ymm0
+       vpermpd $76, %ymm0, %ymm0
        ret
        .cfi_endproc
 .LFE1:
@@ -29,8 +32,8 @@ bar:
 baz:
 .LFB2:
        .cfi_startproc
-       vunpckhpd       %xmm0, %xmm0, %xmm0
-       vmovhpd (%rdi), %xmm0, %xmm0
+       vmovddup        (%rdi), %xmm1
+       vunpckhpd       %xmm1, %xmm0, %xmm0
        ret
        .cfi_endproc
 .LFE2:
@@ -41,7 +44,9 @@ baz:
 qux:
 .LFB3:
        .cfi_startproc
-       vmovhpd (%rdi), %xmm0, %xmm0
+       vmovapd %xmm0, %xmm1
+       vmovddup        (%rdi), %xmm0
+       vmovsd  %xmm1, %xmm0, %xmm0
        ret
        .cfi_endproc
 .LFE3:
@@ -52,12 +57,13 @@ qux:
 corge:
 .LFB4:
        .cfi_startproc
-       vextractf128    $0x1, %ymm0, %xmm0
-       vunpckhpd       %xmm0, %xmm0, %xmm0
-       vmovhpd (%rdi), %xmm0, %xmm0
+       vbroadcastsd    (%rdi), %ymm2
+       vpermpd $78, %ymm0, %ymm1
+       vperm2f128      $2, %ymm2, %ymm0, %ymm0
+       vshufpd $11, %ymm0, %ymm1, %ymm0
        ret
        .cfi_endproc
 .LFE4:
        .size   corge, .-corge
-       .ident  "GCC: (GNU) 9.2.1 20191121"
+       .ident  "GCC: (GNU) 10.0.0 20191205 (experimental)"
        .section        .note.GNU-stack,"",@progbits

None of it is shorter, only baz is the same size as before.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92803
[Bug 92803] [10 Regression] error: type mismatch in 'vec_perm_expr' since
r278764