glsl/loops: replace loop controls with a normative bound.

This patch replaces the ir_loop fields "from", "to", "increment",
"counter", and "cmp" with a single integer ("normative_bound") that
serves the same purpose.

I've used the name "normative_bound" to emphasize the fact that the
back-end is required to emit code to prevent the loop from running
more than normative_bound times.  (By contrast, an "informative" bound
would be a bound that is informational only).

Reviewed-by: Jordan Justen <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>

2 files changed, 8 insertions, 4 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
index 3e32f6e0eba..70eb9979442 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
@@ -2181,8 +2181,10 @@ fs_visitor::visit(ir_if *ir)
 void
 fs_visitor::visit(ir_loop *ir)
 {
-   /* Any bounded loops should have been lowered by lower_bounded_loops(). */
-   assert(ir->counter == NULL);
+   /* Any normative loop bounds should have been lowered by
+    * lower_bounded_loops().
+    */
+   assert(ir->normative_bound < 0);
 
    if (brw->gen < 6 && dispatch_width == 16) {
       fail("Can't support (non-uniform) control flow on 16-wide\n");
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
index cf62e7ed0b0..d0e378b76ef 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
@@ -1007,8 +1007,10 @@ vec4_visitor::visit(ir_variable *ir)
 void
 vec4_visitor::visit(ir_loop *ir)
 {
-   /* Any bounded loops should have been lowered by lower_bounded_loops(). */
-   assert(ir->counter == NULL);
+   /* Any normative loop bounds should have been lowered by
+    * lower_bounded_loops().
+    */
+   assert(ir->normative_bound < 0);
 
    /* We don't want debugging output to print the whole body of the
     * loop as the annotation.