Mesa (master): i965: Reject shaders with uninlined function calls instead of hanging.

[Eric Anholt]

Module: Mesa
Branch: master
Commit: ee29b861298bd165e6b104b218f31c78aed3682a
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=ee29b861298bd165e6b104b218f31c78aed3682a

Author: Eric Anholt <eric at anholt.net>
Date:   Thu Apr 29 13:35:56 2010 -0700

i965: Reject shaders with uninlined function calls instead of hanging.

Most of the failure from using uninlined function calls ends up being
just bad rendering, but nested function calls in the VS currently hang
the GPU, so reject them and explain why.

---

 src/mesa/drivers/dri/i965/brw_program.c |   34 ++++++++++++++++++++++++++++++-
 1 files changed, 33 insertions(+), 1 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_program.c b/src/mesa/drivers/dri/i965/brw_program.c
index 1fd957b..41a1f43 100644
--- a/src/mesa/drivers/dri/i965/brw_program.c
+++ b/src/mesa/drivers/dri/i965/brw_program.c
@@ -34,6 +34,7 @@
 #include "shader/prog_parameter.h"
 #include "shader/program.h"
 #include "shader/programopt.h"
+#include "shader/shader_api.h"
 #include "tnl/tnl.h"
 
 #include "brw_context.h"
@@ -119,12 +120,28 @@ static GLboolean brwIsProgramNative( GLcontext *ctx,
    return GL_TRUE;
 }
 
+static void
+shader_error(GLcontext *ctx, struct gl_program *prog, const char *msg)
+{
+   struct gl_shader_program *shader;
+
+   shader = _mesa_lookup_shader_program(ctx, prog->Id);
+
+   if (shader) {
+      if (shader->InfoLog) {
+	 free(shader->InfoLog);
+      }
+      shader->InfoLog = _mesa_strdup(msg);
+      shader->LinkStatus = GL_FALSE;
+   }
+}
 
 static GLboolean brwProgramStringNotify( GLcontext *ctx,
                                          GLenum target,
                                          struct gl_program *prog )
 {
    struct brw_context *brw = brw_context(ctx);
+   int i;
 
    if (target == GL_FRAGMENT_PROGRAM_ARB) {
       struct gl_fragment_program *fprog = (struct gl_fragment_program *) prog;
@@ -160,7 +177,22 @@ static GLboolean brwProgramStringNotify( GLcontext *ctx,
       _tnl_program_string(ctx, target, prog);
    }
 
-   /* XXX check if program is legal, within limits */
+   /* Reject programs with subroutines, which are totally broken at the moment
+    * (all program flows return when any program flow returns, and
+    * the VS also hangs if a function call calls a function.
+    *
+    * See piglit glsl-{vs,fs}-functions-[23] tests.
+    */
+   for (i = 0; i < prog->NumInstructions; i++) {
+      if (prog->Instructions[i].Opcode == OPCODE_CAL) {
+	 shader_error(ctx, prog,
+		      "i965 driver doesn't yet support uninlined function "
+		      "calls.  Move to using a single return statement at "
+		      "the end of the function to work around it.");
+	 return GL_FALSE;
+      }
+   }
+
    return GL_TRUE;
 }