i915: Add optional support for ARB_fragment_shader under a driconf option.

Other vendors have enabled ARB_fragment_shader as part of OpenGL 2.0
enablement even on hardware like the 915 with no dynamic branching or
dFdx/dFdy support.  But for now we'll leave it disabled because we don't
do any flattening of ifs or loops, which is rather restrictive.

This support is not complete, and may be unstable depending on your shaders.
It passes 10/15 of the piglit glsl tests, but hangs on glean glsl1.

4 files changed, 15 insertions, 3 deletions

diff --git a/src/mesa/drivers/dri/i915/i915_fragprog.c b/src/mesa/drivers/dri/i915/i915_fragprog.c
index d5659e762f..d9c61446f5 100644
--- a/src/mesa/drivers/dri/i915/i915_fragprog.c
+++ b/src/mesa/drivers/dri/i915/i915_fragprog.c
@@ -160,6 +160,7 @@ src_vector(struct i915_fragment_program *p,
    case PROGRAM_CONSTANT:
    case PROGRAM_STATE_VAR:
    case PROGRAM_NAMED_PARAM:
+   case PROGRAM_UNIFORM:
       src =
          i915_emit_param4fv(p,
                             program->Base.Parameters->ParameterValues[source->
diff --git a/src/mesa/drivers/dri/intel/intel_context.h b/src/mesa/drivers/dri/intel/intel_context.h
index c743ab1c24..b104096912 100644
--- a/src/mesa/drivers/dri/intel/intel_context.h
+++ b/src/mesa/drivers/dri/intel/intel_context.h
@@ -293,7 +293,6 @@ struct intel_context
 
    GLboolean use_texture_tiling;
    GLboolean use_early_z;
-
    drm_clip_rect_t fboRect;     /**< cliprect for FBO rendering */
 
    int perf_boxes;
diff --git a/src/mesa/drivers/dri/intel/intel_extensions.c b/src/mesa/drivers/dri/intel/intel_extensions.c
index f10eda7cc7..6831cbbfc8 100644
--- a/src/mesa/drivers/dri/intel/intel_extensions.c
+++ b/src/mesa/drivers/dri/intel/intel_extensions.c
@@ -182,6 +182,10 @@ static const struct dri_extension ttm_extensions[] = {
    { NULL, NULL }
 };
 
+static const struct dri_extension fragment_shader_extensions[] = {
+   { "GL_ARB_fragment_shader",            NULL },
+   { NULL, NULL }
+};
 
 /**
  * Initializes potential list of extensions if ctx == NULL, or actually enables
@@ -205,6 +209,10 @@ intelInitExtensions(GLcontext *ctx, GLboolean enable_imaging)
       driInitExtensions(ctx, brw_extensions, GL_FALSE);
 
    if (intel == NULL || IS_915(intel->intelScreen->deviceID)
-       || IS_945(intel->intelScreen->deviceID))
+       || IS_945(intel->intelScreen->deviceID)) {
       driInitExtensions(ctx, i915_extensions, GL_FALSE);
+
+      if (intel == NULL || driQueryOptionb(&intel->optionCache, "fragment_shader"))
+	 driInitExtensions(ctx, fragment_shader_extensions, GL_FALSE);
+   }
 }
diff --git a/src/mesa/drivers/dri/intel/intel_screen.c b/src/mesa/drivers/dri/intel/intel_screen.c
index 1b8c56e68d..2478e63637 100644
--- a/src/mesa/drivers/dri/intel/intel_screen.c
+++ b/src/mesa/drivers/dri/intel/intel_screen.c
@@ -79,6 +79,10 @@ PUBLIC const char __driConfigOptions[] =
 	 DRI_CONF_DESC(en, "Enable early Z in classic mode (unstable, 945-only).")
       DRI_CONF_OPT_END
 
+      DRI_CONF_OPT_BEGIN(fragment_shader, bool, false)
+	 DRI_CONF_DESC(en, "Enable limited ARB_fragment_shader support on 915/945.")
+      DRI_CONF_OPT_END
+
    DRI_CONF_SECTION_END
    DRI_CONF_SECTION_QUALITY
       DRI_CONF_FORCE_S3TC_ENABLE(false)
@@ -91,7 +95,7 @@ PUBLIC const char __driConfigOptions[] =
    DRI_CONF_SECTION_END
 DRI_CONF_END;
 
-const GLuint __driNConfigOptions = 10;
+const GLuint __driNConfigOptions = 11;
 
 #ifdef USE_NEW_INTERFACE
 static PFNGLXCREATECONTEXTMODES create_context_modes = NULL;