On 03/01/2014 12:18 AM, Kenneth Graunke wrote:
opt_algebraic was translating lrp(x, 0, a) into add(x, -mul(x, a)).
Unfortunately, this references "x" twice, which is invalid in the IR,
leading to assertion failures in the validator.
Right... and Matt probably didn't notice this because he tests release
builds because they make piglit runs so much faster. Hmm... isn't -Og
credible yet? :(
Normally, cloning IR solves this. However, "x" could actually be an
arbitrary expression tree, so copying it could result in huge piles
of wasted computation. This is why we avoid reusing subexpressions.
The other way to solve this is to assign x to a temporary. Isn't x-a*x
slightly better because it can be implemented as MAD?
I don't have a strong opinion... if you don't feel like doing a temp,
Reviewed-by: Ian Romanick <ian.d.roman...@intel.com>
Instead, transform it into mul(x, add(1.0, -a)), which is equivalent
but doesn't need two references to "x".
Fixes a regression since d5fa8a95621169, which isn't in any stable
branches. Fixes 18 shaders in shader-db (bastion and yofrankie).
Signed-off-by: Kenneth Graunke <kenn...@whitecape.org>
---
src/glsl/opt_algebraic.cpp | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
Here's the shader-db output comparing master to this:
GAINED: shaders/bastion/48.shader_test fs16
GAINED: shaders/bastion/48.shader_test fs8
GAINED: shaders/bastion/48.shader_test vs
GAINED: shaders/yofrankie/27.shader_test fs16
GAINED: shaders/yofrankie/27.shader_test fs8
GAINED: shaders/yofrankie/27.shader_test vs
GAINED: shaders/yofrankie/30.shader_test fs16
GAINED: shaders/yofrankie/30.shader_test fs8
GAINED: shaders/yofrankie/30.shader_test vs
GAINED: shaders/yofrankie/48.shader_test fs16
GAINED: shaders/yofrankie/48.shader_test fs8
GAINED: shaders/yofrankie/48.shader_test vs
GAINED: shaders/yofrankie/87.shader_test fs16
GAINED: shaders/yofrankie/87.shader_test fs8
GAINED: shaders/yofrankie/87.shader_test vs
GAINED: shaders/yofrankie/9.shader_test fs16
GAINED: shaders/yofrankie/9.shader_test fs8
GAINED: shaders/yofrankie/9.shader_test vs
total instructions in shared programs: 1726391 -> 1726391 (0.00%)
instructions in affected programs: 0 -> 0
GAINED: 18
LOST:
diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index 778638c..5c49a78 100644
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -571,7 +571,9 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
} else if (is_vec_zero(op_const[0])) {
return mul(ir->operands[1], ir->operands[2]);
} else if (is_vec_zero(op_const[1])) {
- return add(ir->operands[0], neg(mul(ir->operands[0],
ir->operands[2])));
+ unsigned op2_components = ir->operands[2]->type->vector_elements;
+ ir_constant *one = new(mem_ctx) ir_constant(1.0f, op2_components);
+ return mul(ir->operands[0], add(one, neg(ir->operands[2])));
}
break;
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