Vertex Shader: Zero OutputVertex to avoid denormals

Unused OutputVertex attributes were being left un-initialized. The
leftover garbage sometimes decoded as floating-point denormalized
values, causing fallbacks to microcode and massive slowdowns in the rest
of the rasterization pipeline even though the results were unused. By
zeroing the structure we ensure these attributes only contain harmless
zeros.
This commit is contained in:
Yuri Kunde Schlesner 2014-12-28 18:20:33 -02:00
parent 487a80f9f7
commit d151d797b1

View File

@ -469,6 +469,10 @@ OutputVertex RunShader(const InputVertex& input, int num_attributes)
// Setup output register table // Setup output register table
OutputVertex ret; OutputVertex ret;
// Zero output so that attributes which aren't output won't have denormals in them, which will
// slow us down later.
memset(&ret, 0, sizeof(ret));
for (int i = 0; i < 7; ++i) { for (int i = 0; i < 7; ++i) {
const auto& output_register_map = registers.vs_output_attributes[i]; const auto& output_register_map = registers.vs_output_attributes[i];