i965: Disable the swrast context setup on GL 3.1 core.

I've reviewed the code, and the swrast callsites remaining are all in
drawpixels/copypixels/bitmap/accum, or _swrast_BlitFramebuffer that shouldn't
be hit.  A piglit run with the context setup disabled on legacy GL and GLES2
showed regressions only in the copypixels and drawpixels tests.

If the context type is forced, this reduces the shader_runner maximum heap
size for glsl-algebraic-add-add-1.shader_test from 15,137,496b to 4,165,376b.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Chad Versace <chad.versace@linux.intel.com>

3 files changed, 34 insertions, 15 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 7f8197d..f83f89f 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -140,7 +140,9 @@ brwCreateContext(int api,
    /* Initialize swrast, tnl driver tables: */
    intelInitSpanFuncs(ctx);
 
-   TNL_CONTEXT(ctx)->Driver.RunPipeline = _tnl_run_pipeline;
+   TNLcontext *tnl = TNL_CONTEXT(ctx);
+   if (tnl)
+      tnl->Driver.RunPipeline = _tnl_run_pipeline;
 
    ctx->Const.MaxDualSourceDrawBuffers = 1;
    ctx->Const.MaxDrawBuffers = BRW_MAX_DRAW_BUFFERS;
diff --git a/src/mesa/drivers/dri/intel/intel_context.c b/src/mesa/drivers/dri/intel/intel_context.c
index 233172f..25334da 100644
--- a/src/mesa/drivers/dri/intel/intel_context.c
+++ b/src/mesa/drivers/dri/intel/intel_context.c
@@ -500,7 +500,8 @@ intelInvalidateState(struct gl_context * ctx, GLuint new_state)
 {
     struct intel_context *intel = intel_context(ctx);
 
-   _swrast_InvalidateState(ctx, new_state);
+    if (ctx->swrast_context)
+       _swrast_InvalidateState(ctx, new_state);
    _vbo_InvalidateState(ctx, new_state);
 
    intel->NewGLState |= new_state;
@@ -696,15 +697,25 @@ intelInitContext(struct intel_context *intel,
       ctx->Const.MaxRenderbufferSize = 2048;
    }
 
-   /* Initialize the software rasterizer and helper modules. */
-   _swrast_CreateContext(ctx);
+   /* Initialize the software rasterizer and helper modules.
+    *
+    * As of GL 3.1 core, the gen4+ driver doesn't need the swrast context for
+    * software fallbacks (which we have to support on legacy GL to do weird
+    * glDrawPixels(), glBitmap(), and other functions).
+    */
+   if (intel->gen <= 3 || api != API_OPENGL_CORE) {
+      _swrast_CreateContext(ctx);
+   }
+
    _vbo_CreateContext(ctx);
-   _tnl_CreateContext(ctx);
-   _swsetup_CreateContext(ctx);
- 
-   /* Configure swrast to match hardware characteristics: */
-   _swrast_allow_pixel_fog(ctx, false);
-   _swrast_allow_vertex_fog(ctx, true);
+   if (ctx->swrast_context) {
+      _tnl_CreateContext(ctx);
+      _swsetup_CreateContext(ctx);
+
+      /* Configure swrast to match hardware characteristics: */
+      _swrast_allow_pixel_fog(ctx, false);
+      _swrast_allow_vertex_fog(ctx, true);
+   }
 
    _mesa_meta_init(ctx);
 
@@ -782,6 +793,7 @@ intelDestroyContext(__DRIcontext * driContextPriv)
 {
    struct intel_context *intel =
       (struct intel_context *) driContextPriv->driverPrivate;
+   struct gl_context *ctx = &intel->ctx;
 
    assert(intel);               /* should never be null */
    if (intel) {
@@ -797,11 +809,14 @@ intelDestroyContext(__DRIcontext * driContextPriv)
 
       intel->vtbl.destroy(intel);
 
-      _swsetup_DestroyContext(&intel->ctx);
-      _tnl_DestroyContext(&intel->ctx);
+      if (ctx->swrast_context) {
+         _swsetup_DestroyContext(&intel->ctx);
+         _tnl_DestroyContext(&intel->ctx);
+      }
       _vbo_DestroyContext(&intel->ctx);
 
-      _swrast_DestroyContext(&intel->ctx);
+      if (ctx->swrast_context)
+         _swrast_DestroyContext(&intel->ctx);
       intel->Fallback = 0x0;      /* don't call _swrast_Flush later */
 
       intel_batchbuffer_free(intel);
diff --git a/src/mesa/drivers/dri/intel/intel_span.c b/src/mesa/drivers/dri/intel/intel_span.c
index 475c01d..d7eaa41 100644
--- a/src/mesa/drivers/dri/intel/intel_span.c
+++ b/src/mesa/drivers/dri/intel/intel_span.c
@@ -169,8 +169,10 @@ void
 intelInitSpanFuncs(struct gl_context * ctx)
 {
    struct swrast_device_driver *swdd = _swrast_GetDeviceDriverReference(ctx);
-   swdd->SpanRenderStart = intelSpanRenderStart;
-   swdd->SpanRenderFinish = intelSpanRenderFinish;
+   if (swdd) {
+      swdd->SpanRenderStart = intelSpanRenderStart;
+      swdd->SpanRenderFinish = intelSpanRenderFinish;
+   }
 }
 
 void