draw/gs: make sure geometry shaders don't overflow

The specification says that the geometry shader should exit if the
number of emitted vertices is bigger or equal to max_output_vertices and
we can't do that because we're running in the SoA mode, which means that
our storing routines will keep getting called on channels that have
overflown (even though they will be masked out, but we just can't skip
them).
So we need some scratch area where we can keep writing the overflown
vertices without overwriting anything important or crashing.

Signed-off-by: Zack Rusin <[email protected]>
Reviewed-by: Jose Fonseca <[email protected]>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/gallium/auxiliary/draw/draw_llvm.c b/src/gallium/auxiliary/draw/draw_llvm.c
index 0e349783198..33fe40d5e7f 100644
--- a/src/gallium/auxiliary/draw/draw_llvm.c
+++ b/src/gallium/auxiliary/draw/draw_llvm.c
@@ -1287,8 +1287,8 @@ draw_gs_llvm_emit_vertex(const struct lp_build_tgsi_gs_iface *gs_base,
    LLVMValueRef clipmask = lp_build_const_int_vec(gallivm,
                                                   lp_int_type(gs_type), 0);
    LLVMValueRef indices[LP_MAX_VECTOR_LENGTH];
-   LLVMValueRef max_output_vertices =
-      lp_build_const_int32(gallivm, variant->shader->base.max_output_vertices);
+   LLVMValueRef next_prim_offset =
+      lp_build_const_int32(gallivm, variant->shader->base.primitive_boundary);
    LLVMValueRef io = variant->io_ptr;
    unsigned i;
    const struct tgsi_shader_info *gs_info = &variant->shader->base.info;
@@ -1297,7 +1297,7 @@ draw_gs_llvm_emit_vertex(const struct lp_build_tgsi_gs_iface *gs_base,
       LLVMValueRef ind = lp_build_const_int32(gallivm, i);
       LLVMValueRef currently_emitted =
          LLVMBuildExtractElement(builder, emitted_vertices_vec, ind, "");
-      indices[i] = LLVMBuildMul(builder, ind, max_output_vertices, "");
+      indices[i] = LLVMBuildMul(builder, ind, next_prim_offset, "");
       indices[i] = LLVMBuildAdd(builder, indices[i], currently_emitted, "");
    }