opt_constant_propagation.cpp contains constant folding code which can
actually do constant propagation in some cases. It was happily
propagating constants into the left-hand-side of assignments.
For example,
(assign () (var_ref temp) (constant ...))
would brilliantly be turned into:
(assign () (constant ...) (constant ....))
This is a bigger hammer than necessary - it prevents propagation
into the left-hand-side altogether. We could certainly do better
someday. Notably, the constant propagation pass itself already
takes this approach - it's just the constant propagation pass's
built-in constant folding code (which actually propagates, too)
that was broken.
No change in shader-db, but prevents regressions after future commits.
It seems plausible that this could be hit today, but I haven't seen it
happen.
Cc: mesa-sta...@lists.freedesktop.org
Signed-off-by: Kenneth Graunke <kenn...@whitecape.org>
---
src/compiler/glsl/opt_constant_propagation.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/compiler/glsl/opt_constant_propagation.cpp
b/src/compiler/glsl/opt_constant_propagation.cpp
index fbc22b0..6ec4ab4 100644
--- a/src/compiler/glsl/opt_constant_propagation.cpp
+++ b/src/compiler/glsl/opt_constant_propagation.cpp
@@ -138,7 +138,7 @@ public:
void
ir_constant_propagation_visitor::constant_folding(ir_rvalue **rvalue)
{
- if (*rvalue == NULL)
+ if (this->in_assignee || *rvalue == NULL)
return;
if (ir_constant_fold(rvalue))
--
2.9.0
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