[Mesa-dev] [PATCH] Integrate precise trig into configuration infrastructure

[Gurchetan Singh]

With this change, to enable precise SIN and COS instructions
on Intel hardware, one can put

<option name="precise_trig" value="true"/>

in the proper drirc file.

V2: Make option name more generic
---
 src/mesa/drivers/dri/common/xmlpool/t_options.h | 5 +++++
 src/mesa/drivers/dri/i965/brw_compiler.c        | 2 --
 src/mesa/drivers/dri/i965/brw_context.c         | 3 +++
 src/mesa/drivers/dri/i965/intel_screen.c        | 2 ++
 4 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/mesa/drivers/dri/common/xmlpool/t_options.h b/src/mesa/drivers/dri/common/xmlpool/t_options.h
index e5cbc46..4b298a4 100644
--- a/src/mesa/drivers/dri/common/xmlpool/t_options.h
+++ b/src/mesa/drivers/dri/common/xmlpool/t_options.h
@@ -158,6 +158,11 @@ DRI_CONF_OPT_BEGIN_B(force_s3tc_enable, def) \
         DRI_CONF_DESC(en,gettext("Enable S3TC texture compression even if software support is not available")) \
 DRI_CONF_OPT_END
 
+#define DRI_CONF_PRECISE_TRIG(def) \
+DRI_CONF_OPT_BEGIN_B(precise_trig, def) \
+        DRI_CONF_DESC(en,gettext("Prefer accuracy over performance in trig functions")) \
+DRI_CONF_OPT_END
+
 #define DRI_CONF_COLOR_REDUCTION_ROUND 0
 #define DRI_CONF_COLOR_REDUCTION_DITHER 1
 #define DRI_CONF_COLOR_REDUCTION(def) \
diff --git a/src/mesa/drivers/dri/i965/brw_compiler.c b/src/mesa/drivers/dri/i965/brw_compiler.c
index 7c1b7e4..9ef7357 100644
--- a/src/mesa/drivers/dri/i965/brw_compiler.c
+++ b/src/mesa/drivers/dri/i965/brw_compiler.c
@@ -145,8 +145,6 @@ brw_compiler_create(void *mem_ctx, const struct brw_device_info *devinfo)
    brw_fs_alloc_reg_sets(compiler);
    brw_vec4_alloc_reg_set(compiler);
 
-   compiler->precise_trig = env_var_as_boolean("INTEL_PRECISE_TRIG", false);
-
    compiler->scalar_stage[MESA_SHADER_VERTEX] =
       devinfo->gen >= 8 && !(INTEL_DEBUG & DEBUG_VEC4VS);
    compiler->scalar_stage[MESA_SHADER_TESS_CTRL] =
diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 26514a0..160f232 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -776,6 +776,9 @@ brw_process_driconf_options(struct brw_context *brw)
 
    brw->precompile = driQueryOptionb(&brw->optionCache, "shader_precompile");
 
+   brw->intelScreen->compiler->precise_trig =
+      driQueryOptionb(&brw->optionCache, "precise_trig");
+
    ctx->Const.ForceGLSLExtensionsWarn =
       driQueryOptionb(options, "force_glsl_extensions_warn");
 
diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c
index f9b5484..af8c4f4 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.c
+++ b/src/mesa/drivers/dri/i965/intel_screen.c
@@ -65,6 +65,8 @@ DRI_CONF_BEGIN
    DRI_CONF_SECTION_QUALITY
       DRI_CONF_FORCE_S3TC_ENABLE("false")
 
+      DRI_CONF_PRECISE_TRIG("false")
+
       DRI_CONF_OPT_BEGIN(clamp_max_samples, int, -1)
               DRI_CONF_DESC(en, "Clamp the value of GL_MAX_SAMPLES to the "
                             "given integer. If negative, then do not clamp.")
-- 
2.1.2