nir: Unset metadata debug bit if no progress made

NIR metadata validation verifies that the debug bit was unset (by a call
to nir_metadata_preserve) if a NIR optimization pass made progress on
the shader. With the expectation that the NIR shader consists of only a
single main function, it has been safe to call nir_metadata_preserve()
iff progress was made.

However, most optimization passes calculate progress per-function and
then return the union of those calculations. In the case that an
optimization pass makes progress only on a subset of the functions in
the shader metadata validation will detect the debug bit is still set on
any unchanged functions resulting in a failed assertion.

This patch offers a quick solution (short of a larger scale refactoring
which I do not wish to undertake as part of this series) that simply
unsets the debug bit on unchanged functions.

Reviewed-by: Kenneth Graunke <[email protected]>
Reviewed-by: Jason Ekstrand <[email protected]>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/compiler/nir/nir_opt_if.c b/src/compiler/nir/nir_opt_if.c
index d7a7bb2bb26..c2f945d4d59 100644
--- a/src/compiler/nir/nir_opt_if.c
+++ b/src/compiler/nir/nir_opt_if.c
@@ -873,6 +873,10 @@ nir_opt_if(nir_shader *shader)
          nir_lower_regs_to_ssa_impl(function->impl);
 
          progress = true;
+      } else {
+   #ifndef NDEBUG
+         function->impl->valid_metadata &= ~nir_metadata_not_properly_reset;
+   #endif
       }
    }