On Fri, Jul 25, 2025 at 4:45 PM Andrew Stubbs <a...@baylibre.com> wrote:
>
> Hi all,
>
> The optimization options are deliberately passed through to the LTO compiler,
> but when the same mechanism is reused for offloading it ends up forcing the
> host compiler settings onto the device compiler. Maybe this should be removed
> completely, but this patch just fixes a few of them. In particular,
> param_vect_partial_vector_usage is disabled by x86 and this really hurts
> amdgcn.
>
> I also fixed an ambiguous else warning in the generated file by adding braces.
>
> OK for mainline?
OK.
Thanks,
Richard.
> Andrew
>
> gcc/ChangeLog:
>
> * config/gcn/gcn.cc (gcn_option_override): Set default for
> param_vect_partial_vector_usage to "1".
> * optc-save-gen.awk: Don't pass through options marked "NoOffload".
> * params.opt (-param=vect-epilogues-nomask): Add NoOffload.
> (-param=vect-partial-vector-usage): Likewise.
> (-param=vect-inner-loop-cost-factor): Likewise.
> ---
> gcc/config/gcn/gcn.cc | 4 ++++
> gcc/optc-save-gen.awk | 19 +++++++++++++++++--
> gcc/params.opt | 6 +++---
> 3 files changed, 24 insertions(+), 5 deletions(-)
>
> diff --git a/gcc/config/gcn/gcn.cc b/gcc/config/gcn/gcn.cc
> index d451bf43355..f228c022157 100644
> --- a/gcc/config/gcn/gcn.cc
> +++ b/gcc/config/gcn/gcn.cc
> @@ -54,6 +54,7 @@
> #include "gimple.h"
> #include "cgraph.h"
> #include "case-cfn-macros.h"
> +#include "opts.h"
>
> /* This file should be included last. */
> #include "target-def.h"
> @@ -183,6 +184,9 @@ gcn_option_override (void)
>
> if (flag_sram_ecc == HSACO_ATTR_DEFAULT)
> flag_sram_ecc = gcn_devices[gcn_arch].sramecc_default;
> +
> + SET_OPTION_IF_UNSET (&global_options, &global_options_set,
> + param_vect_partial_vector_usage, 1);
> }
>
> /* }}} */
> diff --git a/gcc/optc-save-gen.awk b/gcc/optc-save-gen.awk
> index a3d7e5a478e..31756ec380d 100644
> --- a/gcc/optc-save-gen.awk
> +++ b/gcc/optc-save-gen.awk
> @@ -1313,6 +1313,12 @@ for (i = 0; i < n_opts; i++) {
> # offloading is enabled.
> if (flag_set_p("Target", flags[i]))
> var_target_opt[n_opt_val] = 1;
> +
> + # These options should not be passed from host to target, but
> + # are not actually target specific.
> + if (flag_set_p("NoOffload", flags[i]))
> + var_target_opt[n_opt_val] = 2;
> +
> n_opt_val++;
> }
> }
> @@ -1393,7 +1399,7 @@ for (i = 0; i < n_opt_val; i++) {
> # Do not stream out target-specific opts if offloading is
> # enabled.
> if (var_target_opt[i])
> - print " if (!lto_stream_offload_p)"
> + print " if (!lto_stream_offload_p) {"
> # If applicable, encode the streamed value.
> if (var_opt_optimize_init[i]) {
> print " if (" var_opt_optimize_init[i] " > ("
> var_opt_val_type[i] ") 10)";
> @@ -1403,6 +1409,8 @@ for (i = 0; i < n_opt_val; i++) {
> } else {
> print " bp_pack_var_len_" sgn " (bp, ptr->" name");";
> }
> + if (var_target_opt[i])
> + print "}"
> }
> }
> print " for (size_t i = 0; i < ARRAY_SIZE (ptr->explicit_mask); i++)";
> @@ -1418,10 +1426,14 @@ print " struct
> cl_optimization *ptr ATTRIBUTE_UNUSED)"
> print "{";
> for (i = 0; i < n_opt_val; i++) {
> name = var_opt_val[i]
> - if (var_target_opt[i]) {
> + if (var_target_opt[i] == 1) {
> print "#ifdef ACCEL_COMPILER"
> print "#error accel compiler cannot define Optimization
> attribute for target-specific option " name;
> print "#else"
> + } else if (var_target_opt[i] == 2) {
> + print "#ifdef ACCEL_COMPILER"
> + print " ptr->" name " = global_options." name ";"
> + print "#else"
> }
> otype = var_opt_val_type[i];
> if (otype ~ "^const char \\**$") {
> @@ -1489,6 +1501,9 @@ for (i = 0; i < n_opts; i++) {
> if (flag_set_p("Warning", flags[i]))
> continue;
>
> + if (flag_set_p("NoOffload", flags[i]))
> + continue;
> +
> if (name in checked_options)
> continue;
> checked_options[name]++
> diff --git a/gcc/params.opt b/gcc/params.opt
> index c7d5fd4d13b..ac1b2c7eb26 100644
> --- a/gcc/params.opt
> +++ b/gcc/params.opt
> @@ -1226,7 +1226,7 @@ Common Joined UInteger Var(param_use_canonical_types)
> Init(1) IntegerRange(0, 1)
> Whether to use canonical types.
>
> -param=vect-epilogues-nomask=
> -Common Joined UInteger Var(param_vect_epilogues_nomask) Init(1)
> IntegerRange(0, 1) Param Optimization
> +Common Joined UInteger Var(param_vect_epilogues_nomask) Init(1)
> IntegerRange(0, 1) Param Optimization NoOffload
> Enable loop epilogue vectorization using smaller vector size.
>
> -param=vect-max-layout-candidates=
> @@ -1246,11 +1246,11 @@ Common Joined UInteger
> Var(param_vect_max_version_for_alignment_checks) Init(6)
> Bound on number of runtime checks inserted by the vectorizer's loop
> versioning for alignment check.
>
> -param=vect-partial-vector-usage=
> -Common Joined UInteger Var(param_vect_partial_vector_usage) Init(2)
> IntegerRange(0, 2) Param Optimization
> +Common Joined UInteger Var(param_vect_partial_vector_usage) Init(2)
> IntegerRange(0, 2) Param Optimization NoOffload
> Controls how loop vectorizer uses partial vectors. 0 means never, 1 means
> only for loops whose need to iterate can be removed, 2 means for all loops.
> The default value is 2.
>
> -param=vect-inner-loop-cost-factor=
> -Common Joined UInteger Var(param_vect_inner_loop_cost_factor) Init(50)
> IntegerRange(1, 10000) Param Optimization
> +Common Joined UInteger Var(param_vect_inner_loop_cost_factor) Init(50)
> IntegerRange(1, 10000) Param Optimization NoOffload
> The maximum factor which the loop vectorizer applies to the cost of
> statements in an inner loop relative to the loop being vectorized.
>
> -param=vect-induction-float=
> --
> 2.50.0
>
