[Mesa-dev] [PATCH] ac/nir: fix potential issues when scanning flat_shaded_mask

[Samuel Pitoiset]

As far as I understand, this might overflow and shifted by one
if for example, gl_PrimitiveID is used with flat generic varyings.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
---
 src/amd/common/ac_nir_to_llvm.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
index ea51c3a54a..d4fdb8e8f4 100644
--- a/src/amd/common/ac_nir_to_llvm.c
+++ b/src/amd/common/ac_nir_to_llvm.c
@@ -5545,6 +5545,7 @@ handle_fs_inputs(struct radv_shader_context *ctx,
 	nir_foreach_variable(variable, &nir->inputs)
 		handle_fs_input_decl(ctx, variable);
 
+	uint64_t flat_shaded_mask = 0;
 	unsigned index = 0;
 
 	if (ctx->shader_info->info.ps.uses_input_attachments ||
@@ -5564,8 +5565,8 @@ handle_fs_inputs(struct radv_shader_context *ctx,
 			interp_fs_input(ctx, index, interp_param, ctx->abi.prim_mask,
 					inputs);
 
-			if (!interp_param)
-				ctx->shader_info->fs.flat_shaded_mask |= 1u << index;
+			if (i >= VARYING_SLOT_VAR0 && !interp_param)
+				flat_shaded_mask |= 1u << i;
 			++index;
 		} else if (i == VARYING_SLOT_POS) {
 			for(int i = 0; i < 3; ++i)
@@ -5575,7 +5576,9 @@ handle_fs_inputs(struct radv_shader_context *ctx,
 						  ctx->abi.frag_pos[3]);
 		}
 	}
+
 	ctx->shader_info->fs.num_interp = index;
+	ctx->shader_info->fs.flat_shaded_mask = flat_shaded_mask >> VARYING_SLOT_VAR0;
 	ctx->shader_info->fs.input_mask = ctx->input_mask >> VARYING_SLOT_VAR0;
 
 	if (ctx->shader_info->info.needs_multiview_view_index)
-- 
2.16.2