i965: add software fallback for conformant 3D textures and GL_CLAMP

The i965 hardware cannot do GL_CLAMP behavior on textures; an earlier
commit forced a software fallback if strict conformance was required
(i.e. the INTEL_STRICT_CONFORMANCE environment variable was set) and
2D textures were used, but it was somewhat flawed - it could trigger
the software fallback even if 2D textures weren't enabled, as long
as one texture unit was enabled.

This fixes that, and adds software fallback for GL_CLAMP behavior with
1D and 3D textures.

It also adds support for a particular setting of the INTEL_STRICT_CONFORMANCE
environment variable, which forces software fallbacks to be taken *all*
the time.  This is helpful with debugging.  The value is:
   export INTEL_STRICT_CONFORMANCE=2

2 files changed, 14 insertions, 3 deletions

diff --git a/src/mesa/drivers/dri/intel/intel_context.c b/src/mesa/drivers/dri/intel/intel_context.c
index b3f6fc02dff..65853234f16 100644
--- a/src/mesa/drivers/dri/intel/intel_context.c
+++ b/src/mesa/drivers/dri/intel/intel_context.c
@@ -506,10 +506,16 @@ intelInitContext(struct intel_context *intel,
     * start.
     */
    if (getenv("INTEL_STRICT_CONFORMANCE")) {
-      intel->strict_conformance = 1;
+      unsigned int value = atoi(getenv("INTEL_STRICT_CONFORMANCE"));
+      if (value > 0) {
+         intel->conformance_mode = value;
+      }
+      else {
+         intel->conformance_mode = 1;
+      }
    }
 
-   if (intel->strict_conformance) {
+   if (intel->conformance_mode > 0) {
       ctx->Const.MinLineWidth = 1.0;
       ctx->Const.MinLineWidthAA = 1.0;
       ctx->Const.MaxLineWidth = 1.0;
diff --git a/src/mesa/drivers/dri/intel/intel_context.h b/src/mesa/drivers/dri/intel/intel_context.h
index 18dc43c4a42..f2ecb9eb279 100644
--- a/src/mesa/drivers/dri/intel/intel_context.h
+++ b/src/mesa/drivers/dri/intel/intel_context.h
@@ -229,7 +229,12 @@ struct intel_context
    GLboolean hw_stipple;
    GLboolean depth_buffer_is_float;
    GLboolean no_rast;
-   GLboolean strict_conformance;
+
+   /* 0 - nonconformant, best performance;
+    * 1 - fallback to sw for known conformance bugs
+    * 2 - always fallback to sw
+    */
+   GLuint conformance_mode;
 
    /* State for intelvb.c and inteltris.c.
     */