u_cpu_detect should detect what's really available, not what is used
(though indeed we actually disable u_cpu bits explicitly in gallivm for
some sse features, but this is a hack).
So I think it would be better if u_cpu_detect sets the has_vsx bit
regardless what the env var is and then enable it based on this bit and
the env var.
Otherwise looks good to me.
Roland
Am 19.08.2018 um 23:17 schrieb Vicki Pfau:
> Previously gallivm would attempt to use VSX instructions on all systems
> where it detected that Altivec is supported; however, VSX was added to
> POWER long after Altivec, causing lots of crashes on older POWER/PPC
> hardware, e.g. PPC Macs. By detecting VSX separately from Altivec we can
> automatically disable it on hardware that supports Altivec but not VSX
>
> Signed-off-by: Vicki Pfau <v...@endrift.com>
> ---
> src/gallium/auxiliary/gallivm/lp_bld_misc.cpp | 21 +++----------------
> src/gallium/auxiliary/util/u_cpu_detect.c | 14 ++++++++++++-
> src/gallium/auxiliary/util/u_cpu_detect.h | 1 +
> 3 files changed, 17 insertions(+), 19 deletions(-)
>
> diff --git a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
> b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
> index 79dbedbb56..fcbdd5050f 100644
> --- a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
> +++ b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
> @@ -650,26 +650,11 @@
> lp_build_create_jit_compiler_for_module(LLVMExecutionEngineRef *OutJIT,
> * which are fixed in LLVM 4.0.
> *
> * With LLVM 4.0 or higher:
> - * Make sure VSX instructions are ENABLED, unless
> - * a) the entire -mattr option is overridden via GALLIVM_MATTRS, or
> - * b) VSX instructions are explicitly enabled/disabled via GALLIVM_VSX=1
> or 0.
> + * Make sure VSX instructions are ENABLED (if supported), unless
> + * VSX instructions are explicitly enabled/disabled via GALLIVM_VSX=1 or
> 0.
> */
> if (util_cpu_caps.has_altivec) {
> - char *env_mattrs = getenv("GALLIVM_MATTRS");
> - if (env_mattrs) {
> - MAttrs.push_back(env_mattrs);
> - }
> - else {
> - boolean enable_vsx = true;
> - char *env_vsx = getenv("GALLIVM_VSX");
> - if (env_vsx && env_vsx[0] == '0') {
> - enable_vsx = false;
> - }
> - if (enable_vsx)
> - MAttrs.push_back("+vsx");
> - else
> - MAttrs.push_back("-vsx");
> - }
> + MAttrs.push_back(util_cpu_caps.has_vsx ? "+vsx" : "-vsx");
> }
> #endif
> #endif
> diff --git a/src/gallium/auxiliary/util/u_cpu_detect.c
> b/src/gallium/auxiliary/util/u_cpu_detect.c
> index 3c6ae4ea1a..14003aa769 100644
> --- a/src/gallium/auxiliary/util/u_cpu_detect.c
> +++ b/src/gallium/auxiliary/util/u_cpu_detect.c
> @@ -133,6 +133,7 @@ check_os_altivec_support(void)
> signal(SIGILL, SIG_DFL);
> } else {
> boolean enable_altivec = TRUE; /* Default: enable if available,
> and if not overridden */
> + boolean enable_vsx = TRUE;
> #ifdef DEBUG
> /* Disabling Altivec code generation is not the same as disabling VSX
> code generation,
> * which can be done simply by passing -mattr=-vsx to the LLVM
> compiler; cf.
> @@ -144,6 +145,11 @@ check_os_altivec_support(void)
> enable_altivec = FALSE;
> }
> #endif
> + /* VSX instructions can be explicitly enabled/disabled via
> GALLIVM_VSX=1 or 0 */
> + char *env_vsx = getenv("GALLIVM_VSX");
> + if (env_vsx && env_vsx[0] == '0') {
> + enable_vsx = FALSE;
> + }
> if (enable_altivec) {
> __lv_powerpc_canjump = 1;
>
> @@ -153,8 +159,13 @@ check_os_altivec_support(void)
> :
> : "r" (-1));
>
> - signal(SIGILL, SIG_DFL);
> util_cpu_caps.has_altivec = 1;
> +
> + if (enable_vsx) {
> + __asm __volatile("xxland %vs0, %vs0, %vs0");
> + util_cpu_caps.has_vsx = 1;
> + }
> + signal(SIGILL, SIG_DFL);
> } else {
> util_cpu_caps.has_altivec = 0;
> }
> @@ -536,6 +547,7 @@ util_cpu_detect(void)
> debug_printf("util_cpu_caps.has_3dnow_ext = %u\n",
> util_cpu_caps.has_3dnow_ext);
> debug_printf("util_cpu_caps.has_xop = %u\n", util_cpu_caps.has_xop);
> debug_printf("util_cpu_caps.has_altivec = %u\n",
> util_cpu_caps.has_altivec);
> + debug_printf("util_cpu_caps.has_vsx = %u\n", util_cpu_caps.has_vsx);
> debug_printf("util_cpu_caps.has_neon = %u\n", util_cpu_caps.has_neon);
> debug_printf("util_cpu_caps.has_daz = %u\n", util_cpu_caps.has_daz);
> debug_printf("util_cpu_caps.has_avx512f = %u\n",
> util_cpu_caps.has_avx512f);
> diff --git a/src/gallium/auxiliary/util/u_cpu_detect.h
> b/src/gallium/auxiliary/util/u_cpu_detect.h
> index 7a63d55028..19f5567ca7 100644
> --- a/src/gallium/auxiliary/util/u_cpu_detect.h
> +++ b/src/gallium/auxiliary/util/u_cpu_detect.h
> @@ -71,6 +71,7 @@ struct util_cpu_caps {
> unsigned has_3dnow_ext:1;
> unsigned has_xop:1;
> unsigned has_altivec:1;
> + unsigned has_vsx:1;
> unsigned has_daz:1;
> unsigned has_neon:1;
>
>
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