svga: Don't emit zero writemasks.

This fixes a regression with Lightsmark, where more compact TGSI from Mesa
was causing a zero mask MOV to be emitted for shadow map compare, causing
problems in some backends.

Add a few more assertions to catch cases like this.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/gallium/drivers/svga/svga_tgsi_emit.h b/src/gallium/drivers/svga/svga_tgsi_emit.h
index e8f75485d55..48eced2ecea 100644
--- a/src/gallium/drivers/svga/svga_tgsi_emit.h
+++ b/src/gallium/drivers/svga/svga_tgsi_emit.h
@@ -138,6 +138,7 @@ static INLINE boolean emit_dst( struct svga_shader_emitter *emit,
                          SVGA3dShaderDestToken dest )
 {
    assert(dest.reserved0);
+   assert(dest.mask);
    return svga_shader_emit_dword( emit, dest.value );
 }
 
@@ -267,6 +268,7 @@ static INLINE SVGA3dShaderDestToken
 writemask( SVGA3dShaderDestToken dest,
            unsigned mask )
 {
+   assert(dest.mask & mask);
    dest.mask &= mask;
    return dest;
 }