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shader: Add integer attribute get optimization pass

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Works around an nvidia driver bug, where casting the integer attributes to float and back to an integer always returned 0.
This commit is contained in:
ameerj 2021-12-24 20:00:28 -05:00
parent 640fc1418b
commit 14ac0c2923
9 changed files with 86 additions and 0 deletions
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23
src/shader_recompiler/ir_opt/constant_propagation_pass.cpp
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@ -505,6 +505,29 @@ void FoldBitCast(IR::Inst& inst, IR::Opcode reverse) {
return;
}
}
if constexpr (op == IR::Opcode::BitCastU32F32) {
// Workaround for new NVIDIA driver bug, where:
// uint attr = ftou(itof(gl_InstanceID));
// always returned 0.
// We can instead manually optimize this and work around the driver bug:
// uint attr = uint(gl_InstanceID);
if (arg_inst->GetOpcode() == IR::Opcode::GetAttribute) {
const IR::Attribute attr{arg_inst->Arg(0).Attribute()};
switch (attr) {
case IR::Attribute::PrimitiveId:
case IR::Attribute::InstanceId:
case IR::Attribute::VertexId:
break;
default:
return;
}
// Replace the bitcasts with an integer attribute get
inst.ReplaceOpcode(IR::Opcode::GetAttributeU32);
inst.SetArg(0, arg_inst->Arg(0));
inst.SetArg(1, arg_inst->Arg(1));
return;
}
}
}
void FoldInverseFunc(IR::Inst& inst, IR::Opcode reverse) {