On Wed, Jan 11, 2023 at 11:31 AM Martin Liška <mli...@suse.cz> wrote:
>
> Currently, one can request a huge jump table creation which
> leads to a non-sensual huge output. Moreover, use auto_vec rather
> than a stack-allocated array.
>
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>
> Ready to be installed?
OK.
Thanks,
Richard.
> Thanks,
> Martin
>
> PR middle-end/107976
>
> gcc/ChangeLog:
>
> * params.opt: Limit JT params.
> * stmt.cc (emit_case_dispatch_table): Use auto_vec.
> ---
> gcc/params.opt | 4 ++--
> gcc/stmt.cc | 9 ++++-----
> 2 files changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/gcc/params.opt b/gcc/params.opt
> index e178dec1600..3454700eb91 100644
> --- a/gcc/params.opt
> +++ b/gcc/params.opt
> @@ -327,11 +327,11 @@ Common Joined UInteger
> Var(param_iv_max_considered_uses) Init(250) Param Optimiz
> Bound on number of iv uses in loop optimized in iv optimizations.
>
> -param=jump-table-max-growth-ratio-for-size=
> -Common Joined UInteger Var(param_jump_table_max_growth_ratio_for_size)
> Init(300) Param Optimization
> +Common Joined UInteger Var(param_jump_table_max_growth_ratio_for_size)
> Init(300) IntegerRange(0, 10000) Param Optimization
> The maximum code size growth ratio when expanding into a jump table (in
> percent). The parameter is used when optimizing for size.
>
> -param=jump-table-max-growth-ratio-for-speed=
> -Common Joined UInteger Var(param_jump_table_max_growth_ratio_for_speed)
> Init(800) Param Optimization
> +Common Joined UInteger Var(param_jump_table_max_growth_ratio_for_speed)
> Init(800) IntegerRange(0, 10000) Param Optimization
> The maximum code size growth ratio when expanding into a jump table (in
> percent). The parameter is used when optimizing for speed.
>
> -param=l1-cache-line-size=
> diff --git a/gcc/stmt.cc b/gcc/stmt.cc
> index 82a3e1035ec..b239c02018a 100644
> --- a/gcc/stmt.cc
> +++ b/gcc/stmt.cc
> @@ -746,7 +746,7 @@ emit_case_dispatch_table (tree index_expr, tree
> index_type,
> tree range, basic_block stmt_bb)
> {
> int i, ncases;
> - rtx *labelvec;
> + auto_vec<rtx> labelvec;
> rtx_insn *fallback_label = label_rtx (case_list[0].m_code_label);
> rtx_code_label *table_label = gen_label_rtx ();
> bool has_gaps = false;
> @@ -779,8 +779,7 @@ emit_case_dispatch_table (tree index_expr, tree
> index_type,
> /* Get table of labels to jump to, in order of case index. */
>
> ncases = tree_to_shwi (range) + 1;
> - labelvec = XALLOCAVEC (rtx, ncases);
> - memset (labelvec, 0, ncases * sizeof (rtx));
> + labelvec.safe_grow_cleared (ncases);
>
> for (unsigned j = 0; j < case_list.length (); j++)
> {
> @@ -860,11 +859,11 @@ emit_case_dispatch_table (tree index_expr, tree
> index_type,
> emit_jump_table_data (gen_rtx_ADDR_DIFF_VEC (CASE_VECTOR_MODE,
> gen_rtx_LABEL_REF (Pmode,
>
> table_label),
> - gen_rtvec_v (ncases,
> labelvec),
> + gen_rtvec_v (ncases,
> labelvec.address ()),
> const0_rtx, const0_rtx));
> else
> emit_jump_table_data (gen_rtx_ADDR_VEC (CASE_VECTOR_MODE,
> - gen_rtvec_v (ncases, labelvec)));
> + gen_rtvec_v (ncases,
> labelvec.address ())));
>
> /* Record no drop-through after the table. */
> emit_barrier ();
> --
> 2.39.0
>
