mesa: replace gl_context->Multisample._Enabled with _mesa_is_multisample_enabled.

This removes any dependency on driver validation of the number of
framebuffer samples.

Signed-off-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Tested-by: Brian Paul <brianp@vmware.com>

src/mesa/drivers/dri/i965/brw_util.h

@@ -34,6 +34,7 @@
 #define BRW_UTIL_H
 
 #include "brw_context.h"
+#include "main/framebuffer.h"
 
 extern GLuint brw_translate_blend_factor( GLenum factor );
 extern GLuint brw_translate_blend_equation( GLenum mode );
@@ -49,13 +50,13 @@ brw_get_line_width(struct brw_context *brw)
     * implementation-dependent maximum non-antialiased line width."
     */
    float line_width =
-      CLAMP(!brw->ctx.Multisample._Enabled && !brw->ctx.Line.SmoothFlag
+      CLAMP(!_mesa_is_multisample_enabled(&brw->ctx) && !brw->ctx.Line.SmoothFlag
             ? roundf(brw->ctx.Line.Width) : brw->ctx.Line.Width,
             0.0f, brw->ctx.Const.MaxLineWidth);
    uint32_t line_width_u3_7 = U_FIXED(line_width, 7);
 
    /* Line width of 0 is not allowed when MSAA enabled */
-   if (brw->ctx.Multisample._Enabled) {
+   if (_mesa_is_multisample_enabled(&brw->ctx)) {
       if (line_width_u3_7 == 0)
          line_width_u3_7 = 1;
    } else if (brw->ctx.Line.SmoothFlag && line_width < 1.5f) {

src/mesa/drivers/dri/i965/gen6_cc.c

@@ -198,14 +198,14 @@ gen6_upload_blend_state(struct brw_context *brw)
       if(!is_buffer_zero_integer_format) {
          /* _NEW_MULTISAMPLE */
          blend[b].blend1.alpha_to_coverage =
-            ctx->Multisample._Enabled && ctx->Multisample.SampleAlphaToCoverage;
+            _mesa_is_multisample_enabled(ctx) && ctx->Multisample.SampleAlphaToCoverage;
 
 	/* From SandyBridge PRM, volume 2 Part 1, section 8.2.3, BLEND_STATE:
 	 * DWord 1, Bit 30 (AlphaToOne Enable):
 	 * "If Dual Source Blending is enabled, this bit must be disabled"
 	 */
          WARN_ONCE(ctx->Color.Blend[b]._UsesDualSrc &&
-                   ctx->Multisample._Enabled &&
+                   _mesa_is_multisample_enabled(ctx) &&
                    ctx->Multisample.SampleAlphaToOne,
                    "HW workaround: disabling alpha to one with dual src "
                    "blending\n");
@@ -213,7 +213,7 @@ gen6_upload_blend_state(struct brw_context *brw)
             blend[b].blend1.alpha_to_one = false;
 	 else
 	    blend[b].blend1.alpha_to_one =
-	       ctx->Multisample._Enabled && ctx->Multisample.SampleAlphaToOne;
+	       _mesa_is_multisample_enabled(ctx) && ctx->Multisample.SampleAlphaToOne;
 
          blend[b].blend1.alpha_to_coverage_dither = (brw->gen >= 7);
       }

src/mesa/drivers/dri/i965/gen6_multisample_state.c

@@ -171,7 +171,7 @@ gen6_determine_sample_mask(struct brw_context *brw)
    /* BRW_NEW_NUM_SAMPLES */
    unsigned num_samples = brw->num_samples;
 
-   if (ctx->Multisample._Enabled) {
+   if (_mesa_is_multisample_enabled(ctx)) {
       if (ctx->Multisample.SampleCoverage) {
          coverage = ctx->Multisample.SampleCoverageValue;
          coverage_invert = ctx->Multisample.SampleCoverageInvert;

src/mesa/drivers/dri/i965/gen8_blend_state.c

@@ -65,7 +65,7 @@ gen8_upload_blend_state(struct brw_context *brw)
 
    if (rb_zero_type != GL_INT && rb_zero_type != GL_UNSIGNED_INT) {
       /* _NEW_MULTISAMPLE */
-      if (ctx->Multisample._Enabled) {
+      if (_mesa_is_multisample_enabled(ctx)) {
          if (ctx->Multisample.SampleAlphaToCoverage) {
             blend[0] |= GEN8_BLEND_ALPHA_TO_COVERAGE_ENABLE;
             blend[0] |= GEN8_BLEND_ALPHA_TO_COVERAGE_DITHER_ENABLE;
@@ -183,7 +183,7 @@ gen8_upload_blend_state(struct brw_context *brw)
       * "If Dual Source Blending is enabled, this bit must be disabled."
       */
       WARN_ONCE(ctx->Color.Blend[i]._UsesDualSrc &&
-                ctx->Multisample._Enabled &&
+                _mesa_is_multisample_enabled(ctx) &&
                 ctx->Multisample.SampleAlphaToOne,
                 "HW workaround: disabling alpha to one with dual src "
                 "blending\n");
@@ -226,7 +226,7 @@ gen8_upload_ps_blend(struct brw_context *brw)
       dw1 |= GEN8_PS_BLEND_ALPHA_TEST_ENABLE;
 
    /* _NEW_MULTISAMPLE */
-   if (ctx->Multisample._Enabled && ctx->Multisample.SampleAlphaToCoverage)
+   if (_mesa_is_multisample_enabled(ctx) && ctx->Multisample.SampleAlphaToCoverage)
       dw1 |= GEN8_PS_BLEND_ALPHA_TO_COVERAGE_ENABLE;
 
    /* Used for implementing the following bit of GL_EXT_texture_integer:

src/mesa/drivers/dri/i965/gen8_depth_state.c

@@ -29,6 +29,7 @@
 #include "brw_state.h"
 #include "brw_defines.h"
 #include "brw_wm.h"
+#include "main/framebuffer.h"
 
 /**
  * Helper function to emit depth related command packets.
@@ -303,7 +304,7 @@ pma_fix_enable(const struct brw_context *brw)
    const bool kill_pixel =
       brw->wm.prog_data->uses_kill ||
       brw->wm.prog_data->uses_omask ||
-      (ctx->Multisample._Enabled && ctx->Multisample.SampleAlphaToCoverage) ||
+      (_mesa_is_multisample_enabled(ctx) && ctx->Multisample.SampleAlphaToCoverage) ||
       ctx->Color.AlphaEnabled;
 
    /* The big formula in CACHE_MODE_1::NP PMA FIX ENABLE. */

src/mesa/drivers/dri/i965/gen8_sf_state.c

@@ -178,7 +178,7 @@ upload_sf(struct brw_context *brw)
       dw3 |= GEN6_SF_USE_STATE_POINT_WIDTH;
 
    /* _NEW_POINT | _NEW_MULTISAMPLE */
-   if ((ctx->Point.SmoothFlag || ctx->Multisample._Enabled) &&
+   if ((ctx->Point.SmoothFlag || _mesa_is_multisample_enabled(ctx)) &&
        !ctx->Point.PointSprite) {
       dw3 |= GEN8_SF_SMOOTH_POINT_ENABLE;
    }
@@ -249,7 +249,7 @@ upload_raster(struct brw_context *brw)
    if (ctx->Point.SmoothFlag)
       dw1 |= GEN8_RASTER_SMOOTH_POINT_ENABLE;
 
-   if (ctx->Multisample._Enabled)
+   if (_mesa_is_multisample_enabled(ctx))
       dw1 |= GEN8_RASTER_API_MULTISAMPLE_ENABLE;
 
    if (ctx->Polygon.OffsetFill)

src/mesa/main/framebuffer.c

@@ -983,3 +983,22 @@ _mesa_is_front_buffer_drawing(const struct gl_framebuffer *fb)
    return (fb->_NumColorDrawBuffers >= 1 &&
            fb->_ColorDrawBufferIndexes[0] == BUFFER_FRONT_LEFT);
 }
+
+static inline GLuint
+_mesa_geometric_nonvalidated_samples(const struct gl_framebuffer *buffer)
+{
+   return buffer->_HasAttachments ?
+      buffer->Visual.samples :
+      buffer->DefaultGeometry.NumSamples;
+}
+
+bool _mesa_is_multisample_enabled(const struct gl_context *ctx)
+{
+   /* The sample count may not be validated by the driver, but when it is set,
+    * we know that is in a valid range and no driver should ever validate a
+    * multisampled framebuffer to non-multisampled and vice-versa.
+    */
+   return ctx->Multisample.Enabled &&
+          ctx->DrawBuffer &&
+          _mesa_geometric_nonvalidated_samples(ctx->DrawBuffer) > 1;
+}

src/mesa/main/framebuffer.h

@@ -146,4 +146,7 @@ _mesa_is_front_buffer_reading(const struct gl_framebuffer *fb);
 extern bool
 _mesa_is_front_buffer_drawing(const struct gl_framebuffer *fb);
 
+extern bool
+_mesa_is_multisample_enabled(const struct gl_context *ctx);
+
 #endif /* FRAMEBUFFER_H */

src/mesa/main/mtypes.h

@@ -667,7 +667,6 @@ struct gl_list_attrib
 struct gl_multisample_attrib
 {
    GLboolean Enabled;
-   GLboolean _Enabled;   /**< true if Enabled and multisample buffer */
    GLboolean SampleAlphaToCoverage;
    GLboolean SampleAlphaToOne;
    GLboolean SampleCoverage;

src/mesa/main/state.c

@@ -343,20 +343,6 @@ update_frontbit(struct gl_context *ctx)
 }
 
 
-/**
- * Update derived multisample state.
- */
-static void
-update_multisample(struct gl_context *ctx)
-{
-   ctx->Multisample._Enabled = GL_FALSE;
-   if (ctx->Multisample.Enabled &&
-       ctx->DrawBuffer &&
-       _mesa_geometric_samples(ctx->DrawBuffer) > 0)
-      ctx->Multisample._Enabled = GL_TRUE;
-}
-
-
 /**
  * Update the ctx->VertexProgram._TwoSideEnabled flag.
  */
@@ -450,9 +436,6 @@ _mesa_update_state_locked( struct gl_context *ctx )
    if (new_state & _NEW_PIXEL)
       _mesa_update_pixel( ctx, new_state );
 
-   if (new_state & (_NEW_MULTISAMPLE | _NEW_BUFFERS))
-      update_multisample( ctx );
-
    /* ctx->_NeedEyeCoords is now up to date.
     *
     * If the truth value of this variable has changed, update for the

src/mesa/program/prog_statevars.c

@@ -502,7 +502,7 @@ _mesa_fetch_state(struct gl_context *ctx, const gl_state_index state[],
                minImplSize = ctx->Const.MinPointSizeAA;
                maxImplSize = ctx->Const.MaxPointSize;
             }
-            else if (ctx->Point.SmoothFlag || ctx->Multisample._Enabled) {
+            else if (ctx->Point.SmoothFlag || _mesa_is_multisample_enabled(ctx)) {
                minImplSize = ctx->Const.MinPointSizeAA;
                maxImplSize = ctx->Const.MaxPointSizeAA;
             }

src/mesa/state_tracker/st_atom_rasterizer.c

@@ -31,6 +31,7 @@
   */
  
 #include "main/macros.h"
+#include "main/framebuffer.h"
 #include "st_context.h"
 #include "st_atom.h"
 #include "st_debug.h"
@@ -235,12 +236,12 @@ static void update_raster_state( struct st_context *st )
    raster->line_stipple_factor = ctx->Line.StippleFactor - 1;
 
    /* _NEW_MULTISAMPLE */
-   raster->multisample = ctx->Multisample._Enabled;
+   raster->multisample = _mesa_is_multisample_enabled(ctx);
 
    /* _NEW_MULTISAMPLE | _NEW_BUFFERS */
    raster->force_persample_interp =
          !st->force_persample_in_shader &&
-         ctx->Multisample._Enabled &&
+         _mesa_is_multisample_enabled(ctx) &&
          ctx->Multisample.SampleShading &&
          ctx->Multisample.MinSampleShadingValue *
          ctx->DrawBuffer->Visual.samples > 1;

src/mesa/state_tracker/st_atom_shader.c

@@ -74,7 +74,7 @@ update_fp( struct st_context *st )
    /* _NEW_MULTISAMPLE | _NEW_BUFFERS */
    key.persample_shading =
       st->force_persample_in_shader &&
-      st->ctx->Multisample._Enabled &&
+      _mesa_is_multisample_enabled(st->ctx) &&
       st->ctx->Multisample.SampleShading &&
       st->ctx->Multisample.MinSampleShadingValue *
       _mesa_geometric_samples(st->ctx->DrawBuffer) > 1;

src/mesa/swrast/s_points.c

@@ -22,7 +22,7 @@
  * OTHER DEALINGS IN THE SOFTWARE.
  */
 
-
+#include "main/framebuffer.h"
 #include "main/glheader.h"
 #include "main/macros.h"
 #include "s_context.h"
@@ -257,7 +257,7 @@ smooth_point(struct gl_context *ctx, const SWvertex *vert)
    size = get_size(ctx, vert, GL_TRUE);
 
    /* alpha attenuation / fade factor */
-   if (ctx->Multisample._Enabled) {
+   if (_mesa_is_multisample_enabled(ctx)) {
       if (vert->pointSize >= ctx->Point.Threshold) {
          alphaAtten = 1.0F;
       }