llvmpipe/draw: handle constant buffer limits and robustness (v1.1)

TGSI expect vec4 of constants for it's current code paths, and when
doing indirect accesses it does the comparison on vec4 indexes,
however NIR does the indexing on packed float indexes.

This also align the compute path with the other shaders, and
should improve robustness (at least under Vulkan)

Fixes:
KHR-NoContext.gl43.robust_buffer_access_behavior.uniform_buffer

v1.1:
rename variable to something more meaningful (Roland)

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5971>

4 files changed, 18 insertions, 8 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_context.c b/src/gallium/drivers/llvmpipe/lp_context.c
index 58073f3a7f6..05dc33ef4e2 100644
--- a/src/gallium/drivers/llvmpipe/lp_context.c
+++ b/src/gallium/drivers/llvmpipe/lp_context.c
@@ -47,6 +47,7 @@
 #include "lp_query.h"
 #include "lp_setup.h"
 #include "lp_screen.h"
+
 /* This is only safe if there's just one concurrent context */
 #ifdef EMBEDDED_DEVICE
 #define USE_GLOBAL_LLVM_CONTEXT
@@ -222,6 +223,9 @@ llvmpipe_create_context(struct pipe_screen *screen, void *priv,
                                  llvmpipe_screen(screen),
                                  lp_draw_disk_cache_find_shader,
                                  lp_draw_disk_cache_insert_shader);
+
+   draw_set_constant_buffer_stride(llvmpipe->draw, lp_get_constant_buffer_stride(screen));
+
    /* FIXME: devise alternative to draw_texture_samplers */
 
    llvmpipe->setup = lp_setup_create( &llvmpipe->pipe,
diff --git a/src/gallium/drivers/llvmpipe/lp_screen.h b/src/gallium/drivers/llvmpipe/lp_screen.h
index 88f87f9dcbd..6b3798e4d7a 100644
--- a/src/gallium/drivers/llvmpipe/lp_screen.h
+++ b/src/gallium/drivers/llvmpipe/lp_screen.h
@@ -82,6 +82,10 @@ llvmpipe_screen( struct pipe_screen *pipe )
    return (struct llvmpipe_screen *)pipe;
 }
 
-
+static inline unsigned lp_get_constant_buffer_stride(struct pipe_screen *_screen)
+{
+   struct llvmpipe_screen *screen = llvmpipe_screen(_screen);
+   return screen->use_tgsi ? (sizeof(float) * 4) : sizeof(float);
+}
 
 #endif /* LP_SCREEN_H */
diff --git a/src/gallium/drivers/llvmpipe/lp_setup.c b/src/gallium/drivers/llvmpipe/lp_setup.c
index a3e2a7ed7e4..550062ffcfc 100644
--- a/src/gallium/drivers/llvmpipe/lp_setup.c
+++ b/src/gallium/drivers/llvmpipe/lp_setup.c
@@ -1201,7 +1201,7 @@ try_update_scene_state( struct lp_setup_context *setup )
             current_data = (ubyte *) setup->constants[i].current.user_buffer;
          }
 
-         if (current_data) {
+         if (current_data && current_size >= sizeof(float)) {
             current_data += setup->constants[i].current.buffer_offset;
 
             /* TODO: copy only the actually used constants? */
@@ -1235,7 +1235,7 @@ try_update_scene_state( struct lp_setup_context *setup )
          }
 
          num_constants =
-            DIV_ROUND_UP(setup->constants[i].stored_size, (sizeof(float) * 4));
+            DIV_ROUND_UP(setup->constants[i].stored_size, lp_get_constant_buffer_stride(scene->pipe->screen));
          setup->fs.current.jit_context.num_constants[i] = num_constants;
          setup->dirty |= LP_SETUP_NEW_FS;
       }
diff --git a/src/gallium/drivers/llvmpipe/lp_state_cs.c b/src/gallium/drivers/llvmpipe/lp_state_cs.c
index dcdd9b36240..be6d648cd53 100644
--- a/src/gallium/drivers/llvmpipe/lp_state_cs.c
+++ b/src/gallium/drivers/llvmpipe/lp_state_cs.c
@@ -1161,7 +1161,7 @@ update_csctx_consts(struct llvmpipe_context *llvmpipe)
    for (i = 0; i < ARRAY_SIZE(csctx->constants); ++i) {
       struct pipe_resource *buffer = csctx->constants[i].current.buffer;
       const ubyte *current_data = NULL;
-
+      unsigned current_size = csctx->constants[i].current.buffer_size;
       if (buffer) {
          /* resource buffer */
          current_data = (ubyte *) llvmpipe_resource_data(buffer);
@@ -1171,13 +1171,15 @@ update_csctx_consts(struct llvmpipe_context *llvmpipe)
          current_data = (ubyte *) csctx->constants[i].current.user_buffer;
       }
 
-      if (current_data) {
+      if (current_data && current_size >= sizeof(float)) {
          current_data += csctx->constants[i].current.buffer_offset;
-
          csctx->cs.current.jit_context.constants[i] = (const float *)current_data;
-         csctx->cs.current.jit_context.num_constants[i] = csctx->constants[i].current.buffer_size;
+         csctx->cs.current.jit_context.num_constants[i] =
+            DIV_ROUND_UP(csctx->constants[i].current.buffer_size,
+                         lp_get_constant_buffer_stride(llvmpipe->pipe.screen));
       } else {
-         csctx->cs.current.jit_context.constants[i] = NULL;
+         static const float fake_const_buf[4];
+         csctx->cs.current.jit_context.constants[i] = fake_const_buf;
          csctx->cs.current.jit_context.num_constants[i] = 0;
       }
    }