glsl: Rework assignments with write_masks to have LHS chan count match RHS.

It turns out that most people new to this IR are surprised when an
assignment to (say) 3 components on the LHS takes 4 components on the
RHS.  It also makes for quite strange IR output:

(assign (constant bool (1)) (x) (var_ref color) (swiz x (var_ref v) ))
(assign (constant bool (1)) (y) (var_ref color) (swiz yy (var_ref v) ))
(assign (constant bool (1)) (z) (var_ref color) (swiz zzz (var_ref v) ))

But even worse, even we get it wrong, as shown by this line of our
current step(float, vec4):

(assign (constant bool (1)) (w)
	(var_ref t)
	(expression float b2f (expression bool >=
		    (swiz w (var_ref x))(var_ref edge))))

where we try to assign a float to the writemasked-out x channel and
don't supply anything for the actual w channel we're writing.  Drivers
right now just get lucky since ir_to_mesa spams the float value across
all the source channels of a vec4.

Instead, the RHS will now have a number of components equal to the
number of components actually being written.  Hopefully this confuses
everyone less, and it also makes codegen for a scalar target simpler.

Reviewed-by: Kenneth Graunke <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>

1 files changed, 8 insertions, 8 deletions

diff --git a/src/glsl/builtins/ir/noise2 b/src/glsl/builtins/ir/noise2
index 008f8b00f1f..383fccfadfb 100644
--- a/src/glsl/builtins/ir/noise2
+++ b/src/glsl/builtins/ir/noise2
@@ -8,8 +8,8 @@
 
       (assign (constant bool (1)) (x) (var_ref a) (expression float noise (var_ref p)))
       (assign (constant bool (1)) (x) (var_ref b) (expression float noise (expression vec4 + (var_ref p) (constant vec4 (601.0 313.0 29.0 277.0)))))
-      (assign (constant bool (1)) (x) (var_ref t) (swiz xx (var_ref a)))
-      (assign (constant bool (1)) (y) (var_ref t) (swiz xx (var_ref b)))
+      (assign (constant bool (1)) (x) (var_ref t) (var_ref a))
+      (assign (constant bool (1)) (y) (var_ref t) (var_ref b))
       (return (var_ref t))
     ))
 
@@ -22,8 +22,8 @@
 
       (assign (constant bool (1)) (x) (var_ref a) (expression float noise (var_ref p)))
       (assign (constant bool (1)) (x) (var_ref b) (expression float noise (expression vec3 + (var_ref p) (constant vec3 (601.0 313.0 29.0)))))
-      (assign (constant bool (1)) (x) (var_ref t) (swiz xx (var_ref a)))
-      (assign (constant bool (1)) (y) (var_ref t) (swiz xx (var_ref b)))
+      (assign (constant bool (1)) (x) (var_ref t) (var_ref a))
+      (assign (constant bool (1)) (y) (var_ref t) (var_ref b))
       (return (var_ref t))
     ))
 
@@ -38,8 +38,8 @@
 
       (assign (constant bool (1)) (x) (var_ref a) (expression float noise (var_ref p)))
       (assign (constant bool (1)) (x) (var_ref b) (expression float noise (expression vec2 + (var_ref p) (constant vec2 (601.0 313.0)))))
-      (assign (constant bool (1)) (x) (var_ref t) (swiz xx (var_ref a)))
-      (assign (constant bool (1)) (y) (var_ref t) (swiz xx (var_ref b)))
+      (assign (constant bool (1)) (x) (var_ref t) (var_ref a))
+      (assign (constant bool (1)) (y) (var_ref t) (var_ref b))
       (return (var_ref t))
     ))
 
@@ -54,8 +54,8 @@
 
       (assign (constant bool (1)) (x) (var_ref a) (expression float noise (var_ref p)))
       (assign (constant bool (1)) (x) (var_ref b) (expression float noise (expression float + (var_ref p) (constant float (601.0)))))
-      (assign (constant bool (1)) (x) (var_ref t) (swiz xx (var_ref a)))
-      (assign (constant bool (1)) (y) (var_ref t) (swiz xx (var_ref b)))
+      (assign (constant bool (1)) (x) (var_ref t) (var_ref a))
+      (assign (constant bool (1)) (y) (var_ref t) (var_ref b))
       (return (var_ref t))
     ))
 ))