From: Kenneth Graunke Date: Mon, 20 Jun 2016 23:48:02 +0000 (-0700) Subject: glsl: Make constant propagation's folder not propagate into an LHS. X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=acf544404472488eec85fff249cbface7fa477b1;p=mesa.git glsl: Make constant propagation's folder not propagate into an LHS. 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-stable@lists.freedesktop.org Signed-off-by: Kenneth Graunke Reviewed-by: Timothy Arceri --- diff --git a/src/compiler/glsl/opt_constant_propagation.cpp b/src/compiler/glsl/opt_constant_propagation.cpp index fbc22b0e50f..6ec4ab498d9 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))