[aarch64] Use op_mode instead of vmode for op0, op1 in aarch64_vectorize_vec_perm_const

[Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>]

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Hi,
For following test case:

svint32_t foo()
{
  int32x4_t v = (int32x4_t) { 1, 2, 3, 4 };
  svint32_t v2 = svld1rq_s32 (svptrue_b8(), &v[0]);
  return v2;
}

After applying workaround in forwprop to not simplify VEC_PERM_EXPR in
simplify_permutation to avoid type error in middle end (or using
-fno-tree-forwprop)
as mentioned in:
https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598390.html

We get following optimized gimple:
  v2_2 = VEC_PERM_EXPR <{ 1, 2, 3, 4 }, { 1, 2, 3, 4 }, { 0, 1, 2, 3, ... }>;
  return v2_2;

However we hit the following ICE during expansion of vec_perm_expr
because in aarch64_vectorize_vec_perm_const,
op0 is VECTOR_CST, and we call force_reg (VNx4SI, op0), which is incorrect mode
for op0. The patch fixes it by using op_mode instead of vmode in calls
to force_reg
for op0 and op1.

during RTL pass: expand
foo2.c: In function ‘foo’:
foo2.c:8:10: internal compiler error: in emit_move_insn, at expr.cc:4052
    8 |   return v2;
      |          ^~
0x74789b emit_move_insn(rtx_def*, rtx_def*)
        ../../gcc/gcc/expr.cc:4052
0xb8f664 force_reg(machine_mode, rtx_def*)
        ../../gcc/gcc/explow.cc:688
0x134182f aarch64_vectorize_vec_perm_const
        ../../gcc/gcc/config/aarch64/aarch64.cc:24132
0xe63070 expand_vec_perm_const(machine_mode, rtx_def*, rtx_def*,
int_vector_builder<poly_int<2u, long> > const&, machine_mode,
rtx_def*)
        ../../gcc/gcc/optabs.cc:6254
0xbb1569 expand_expr_real_2(separate_ops*, rtx_def*, machine_mode,
expand_modifier)
        ../../gcc/gcc/expr.cc:10273
0xbb6498 expand_expr_real_1(tree_node*, rtx_def*, machine_mode,
expand_modifier, rtx_def**, bool)
        ../../gcc/gcc/expr.cc:10625
0xa897dc expand_expr
        ../../gcc/gcc/expr.h:310
0xa897dc expand_return
        ../../gcc/gcc/cfgexpand.cc:3809
0xa897dc expand_gimple_stmt_1
        ../../gcc/gcc/cfgexpand.cc:3918
0xa897dc expand_gimple_stmt
        ../../gcc/gcc/cfgexpand.cc:4044
0xa8f238 expand_gimple_basic_block
        ../../gcc/gcc/cfgexpand.cc:6096
0xa91187 execute
        ../../gcc/gcc/cfgexpand.cc:6822

Is the patch OK to commit after bootstrap+test on aarch64-linux-gnu ?

Thanks,
Prathamesh

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diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
index 25f4cbb466d..303814b8cca 100644
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -24129,11 +24129,11 @@ aarch64_vectorize_vec_perm_const (machine_mode vmode, machine_mode op_mode,
   d.op_mode = op_mode;
   d.op_vec_flags = aarch64_classify_vector_mode (d.op_mode);
   d.target = target;
-  d.op0 = op0 ? force_reg (vmode, op0) : NULL_RTX;
+  d.op0 = op0 ? force_reg (op_mode, op0) : NULL_RTX;
   if (op0 == op1)
     d.op1 = d.op0;
   else
-    d.op1 = op1 ? force_reg (vmode, op1) : NULL_RTX;
+    d.op1 = op1 ? force_reg (op_mode, op1) : NULL_RTX;
   d.testing_p = !target;
 
   if (!d.testing_p)