Prathamesh Kulkarni <prathamesh.kulka...@linaro.org> writes:
> 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;
Hmm, we really should be able to fold that to a constant. However…
> 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
>
> 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)
…yes, this is OK, thanks.
Richard
