Mesa (master): glsl: validate IR after linking (debug builds only)

[Paul Berry]

Module: Mesa
Branch: master
Commit: c148ef6ddb3dbf256c26d82ed2f45f1fde55a231
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=c148ef6ddb3dbf256c26d82ed2f45f1fde55a231

Author: Paul Berry <stereotype441 at gmail.com>
Date:   Wed Aug  3 15:37:01 2011 -0700

glsl: validate IR after linking (debug builds only)

At least one of the invariants verified by IR validation concerns the
relative ordering of toplevel constructs in the IR: references to
global variables must come after the declarations of those global
variables.

Since linking affects the ordering of toplevel constructs in the IR,
it's possible that a bug in the linker will cause invalid IR to be
generated, even if all the pre-linked shaders are valid.  (In fact,
such a bug was fixed by the previous commit.)

Bugs like this are easily masked by further optimization passes,
particularly inlining.  So to make them easier to track down, this
patch addes an IR validation step right after linking, and before
final optimization occurs.  The validation only occurs on debug
builds.

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

---

 src/glsl/linker.cpp |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 19eb9b5..b54ef41 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -922,6 +922,14 @@ link_intrastage_shaders(void *mem_ctx,
 
    free(linking_shaders);
 
+#ifdef DEBUG
+   /* At this point linked should contain all of the linked IR, so
+    * validate it to make sure nothing went wrong.
+    */
+   if (linked)
+      validate_ir_tree(linked->ir);
+#endif
+
    /* Make a pass over all variable declarations to ensure that arrays with
     * unspecified sizes have a size specified.  The size is inferred from the
     * max_array_access field.