st/mesa: fix _IntegerBuffers bitfield use

Previously we were assuming that all color attachments were active.

Fixes: 8fb966688b ("st/mesa: Disable blending for integer formats.")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/13168
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35014>

src/freedreno/ci/freedreno-a306-fails.txt

@@ -1098,6 +1098,11 @@ spec@nv_copy_image@nv_copy_image-formats@Source: GL_ALPHA16/Destination: GL_ALPH
 spec@glsl-1.30@execution@fs-uint-to-float-of-extract-int8,Fail
 spec@glsl-1.30@execution@fs-uint-to-float-of-extract-int16,Fail
 
+# Failing after bugfix https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35014
+# when we stopped skipping the blend code when an inactive integer buffer was attached
+dEQP-GLES3.functional.draw_buffers_indexed.random.max_implementation_draw_buffers.9,Fail
+dEQP-GLES3.functional.draw_buffers_indexed.random.max_required_draw_buffers.2,Fail
+
 # glcts update
 dEQP-GLES3.functional.fbo.blit.rect.nearest_consistency_out_of_bounds_min_reverse_src_dst_x,Fail
 dEQP-GLES3.functional.fbo.blit.rect.nearest_consistency_out_of_bounds_mag_reverse_src_dst_x,Fail

src/mesa/main/blend.c

@@ -1136,7 +1136,7 @@ _mesa_update_clamp_fragment_color(struct gl_context *ctx,
     * - there is an integer colorbuffer
     */
    if (!drawFb || !drawFb->_HasSNormOrFloatColorBuffer ||
-       drawFb->_IntegerBuffers)
+       drawFb->_IntegerDrawBuffers)
       clamp = GL_FALSE;
    else
       clamp = _mesa_get_clamp_fragment_color(ctx, drawFb);

src/mesa/main/buffers.c

@@ -739,6 +739,28 @@ updated_drawbuffers(struct gl_context *ctx, struct gl_framebuffer *fb)
    }
 }
 
+static void
+update_drawbuffer_mask(struct gl_context *ctx, struct gl_framebuffer *fb,
+                       GLbitfield *buffers, GLbitfield *draw_buffers)
+{
+   *draw_buffers = 0;
+   for (unsigned i = 0; i < fb->_NumColorDrawBuffers; i++) {
+      gl_buffer_index buf = fb->_ColorDrawBufferIndexes[i];
+      if (buf < BUFFER_COLOR0)
+         continue;
+
+      if (*buffers & (1 << (buf - BUFFER_COLOR0)))
+         *draw_buffers |= (1 << i);
+   }
+}
+
+void
+_mesa_update_drawbuffer_masks(struct gl_context *ctx,
+                              struct gl_framebuffer *fb)
+{
+   update_drawbuffer_mask(ctx, fb, &ctx->DrawBuffer->_IntegerBuffers,
+                          &ctx->DrawBuffer->_IntegerDrawBuffers);
+}
 
 /**
  * Helper function to set the GL_DRAW_BUFFER state for the given context and
@@ -817,6 +839,8 @@ _mesa_drawbuffers(struct gl_context *ctx, struct gl_framebuffer *fb,
       fb->_NumColorDrawBuffers = count;
    }
 
+   _mesa_update_drawbuffer_masks(ctx, fb);
+
    /* set remaining outputs to BUFFER_NONE */
    for (buf = fb->_NumColorDrawBuffers; buf < ctx->Const.MaxDrawBuffers; buf++) {
       if (fb->_ColorDrawBufferIndexes[buf] != BUFFER_NONE) {

src/mesa/main/buffers.h

@@ -52,6 +52,10 @@ _mesa_readbuffer(struct gl_context *ctx, struct gl_framebuffer *fb,
 extern void
 _mesa_update_draw_buffers(struct gl_context *ctx);
 
+extern void
+_mesa_update_drawbuffer_masks(struct gl_context *ctx,
+                              struct gl_framebuffer *fb);
+
 extern GLenum
 _mesa_back_to_front_if_single_buffered(const struct gl_framebuffer *fb,
                                        GLenum buffer);

src/mesa/main/draw_validate.c

@@ -155,16 +155,8 @@ _mesa_update_valid_to_render_state(struct gl_context *ctx)
          /* If drawing to integer-valued color buffers, there must be an
           * active fragment shader (GL_EXT_texture_integer).
           */
-         if (ctx->DrawBuffer->_IntegerBuffers) {
+         if (ctx->DrawBuffer->_IntegerDrawBuffers)
-            for (int i = 0; i < ctx->DrawBuffer->_NumColorDrawBuffers; i++) {
+            return;
-               gl_buffer_index buf = ctx->DrawBuffer->_ColorDrawBufferIndexes[i];
-               if (buf < BUFFER_COLOR0)
-                  continue;
-
-               if (ctx->DrawBuffer->_IntegerBuffers & (1 << (buf - BUFFER_COLOR0)))
-                  return;
-            }
-         }
       }
    }
 

src/mesa/main/fbobject.c

@@ -1732,6 +1732,8 @@ _mesa_test_framebuffer_completeness(struct gl_context *ctx,
       return;
    }
 
+   _mesa_update_drawbuffer_masks(ctx, fb);
+
    /* Provisionally set status = COMPLETE ... */
    fb->_Status = GL_FRAMEBUFFER_COMPLETE_EXT;
 

src/mesa/main/framebuffer.c

@@ -1056,6 +1056,6 @@ _mesa_is_multisample_enabled(const struct gl_context *ctx)
 bool
 _mesa_is_alpha_test_enabled(const struct gl_context *ctx)
 {
-   bool buffer0_is_integer = ctx->DrawBuffer->_IntegerBuffers & 0x1;
+   bool buffer0_is_integer = ctx->DrawBuffer->_IntegerDrawBuffers & 0x1;
    return (ctx->Color.AlphaEnabled && !buffer0_is_integer);
 }

src/mesa/main/get.c

@@ -1266,7 +1266,7 @@ find_custom_value(struct gl_context *ctx, const struct value_desc *d, union valu
       break;
    /* GL_EXT_textrue_integer */
    case GL_RGBA_INTEGER_MODE_EXT:
-      v->value_int = (ctx->DrawBuffer->_IntegerBuffers != 0);
+      v->value_int = (ctx->DrawBuffer->_IntegerDrawBuffers != 0);
       break;
    /* GL_ATI_meminfo & GL_NVX_gpu_memory_info */
    case GL_VBO_FREE_MEMORY_ATI:

src/mesa/main/mtypes.h

@@ -2691,7 +2691,8 @@ struct gl_framebuffer
     */
    bool _HasAttachments;
 
-   GLbitfield _IntegerBuffers;  /**< Which color buffers are integer valued */
+   GLbitfield _IntegerBuffers;  /**< Which color buffer attachments are integer valued */
+   GLbitfield _IntegerDrawBuffers;  /**< Which color draw buffers are integer valued */
    GLbitfield _BlendForceAlphaToOne;  /**< Which color buffers need blend factor adjustment */
    GLbitfield _IsRGB;  /**< Which color buffers have an RGB base format? */
    GLbitfield _FP32Buffers; /**< Which color buffers are FP32 */

src/mesa/state_tracker/st_atom_blend.c

@@ -175,8 +175,8 @@ blend_per_rt(const struct st_context *st, unsigned num_cb)
       /* this can only happen if GL_ARB_draw_buffers_blend is enabled */
       return GL_TRUE;
    }
-   if (ctx->DrawBuffer->_IntegerBuffers &&
+   if (ctx->DrawBuffer->_IntegerDrawBuffers &&
-       (ctx->DrawBuffer->_IntegerBuffers != cb_mask)) {
+       (ctx->DrawBuffer->_IntegerDrawBuffers != cb_mask)) {
       /* If there is a mix of integer/non-integer buffers then blending
        * must be handled on a per buffer basis. */
       return GL_TRUE;
@@ -280,7 +280,7 @@ st_update_blend( struct st_context *st )
       /* blending enabled */
       for (i = 0, j = 0; i < num_state; i++) {
          if (!(ctx->Color.BlendEnabled & (1 << i)) ||
-             (ctx->DrawBuffer->_IntegerBuffers & (1 << i)) ||
+             (ctx->DrawBuffer->_IntegerDrawBuffers & (1 << i)) ||
              !blend->rt[i].colormask)
             continue;
 
@@ -340,7 +340,7 @@ st_update_blend( struct st_context *st )
       blend->dither = ctx->Color.DitherFlag;
 
    if (_mesa_is_multisample_enabled(ctx) &&
-       !(ctx->DrawBuffer->_IntegerBuffers & 0x1)) {
+       !(ctx->DrawBuffer->_IntegerDrawBuffers & 0x1)) {
       /* Unlike in gallium/d3d10 these operations are only performed
        * if both msaa is enabled and we have a multisample buffer.
        */

src/mesa/state_tracker/st_atom_depth.c

@@ -129,7 +129,7 @@ st_update_depth_stencil_alpha(struct st_context *st)
    }
 
    if (ctx->Color.AlphaEnabled && !st->lower_alpha_test &&
-       !(ctx->DrawBuffer->_IntegerBuffers & 0x1)) {
+       !(ctx->DrawBuffer->_IntegerDrawBuffers & 0x1)) {
       dsa->alpha_enabled = 1;
       dsa->alpha_func = func_to_gallium(ctx->Color.AlphaFunc);
       dsa->alpha_ref_value = ctx->Color.AlphaRefUnclamped;