On Tue, 20 Sep 2011 18:28:17 -0700, Kenneth Graunke <kenn...@whitecape.org> wrote: > This begins the process of cleaning up and un-muddling our IR. > > Aside from ir_call, our IR is cleanly split into two classes: > - Statements (typeless; used for side effects, control flow) > - Values (deeply nestable, pure, typed expression trees) > > Unfortunately, ir_call confused all this: > - For void functions, we placed ir_call directly in the instruction > stream, treating it as an untyped statement. Yet, it was a subclass > of ir_rvalue, and no other ir_rvalue could be used in this way. > - For functions with a return value, ir_call could be placed in > arbitrary expression trees. While this fit naturally with the source > language, it meant that expressions might not be pure, making it > difficult to transform and optimize them. To combat this, we always > emitted ir_call directly in the RHS of an ir_assignment, only using > a temporary variable in expression trees. Many passes relied on this > assumption; the acos and atan built-ins violated it. > > This patch makes ir_call a statement (ir_instruction) rather than a > value (ir_rvalue). Non-void calls now take a ir_dereference of a > variable, and store the return value there---effectively a call and > assignment rolled into one. They cannot be embedded in expressions. > > All expression trees are now pure, without exception. > > Signed-off-by: Kenneth Graunke <kenn...@whitecape.org>
I spent most of my review time on this looking at the optimization pass changes, so I haven't done as much coverage of the ast-level changes. Reviewed-by: Eric Anholt <e...@anholt.net> > diff --git a/src/glsl/ir_expression_flattening.cpp > b/src/glsl/ir_expression_flattening.cpp > index 0b7c537..3922da8 100644 > --- a/src/glsl/ir_expression_flattening.cpp > +++ b/src/glsl/ir_expression_flattening.cpp > @@ -27,10 +27,8 @@ > * Takes the leaves of expression trees and makes them dereferences of > * assignments of the leaves to temporaries, according to a predicate. > * > - * This is used for automatic function inlining, where we want to take > - * an expression containing a call and move the call out to its own > - * assignment so that we can inline it at the appropriate place in the > - * instruction stream. > + * This is used for breaking down matrix operations, where it's easier to > + * create a temporary and work on each of its vectory components > individually. "vector".
pgp6aJLRunWqR.pgp
Description: PGP signature
_______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
