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GPU/Shaders: Implemented SSY and SYNC as a way to modify control flow during shader execution. 

SSY sets the target label to jump to when the SYNC instruction is executed.
This commit is contained in:
Subv 2018-08-11 15:55:11 -05:00
parent 4f0818144e
commit 305a05f820
1 changed files with 25 additions and 6 deletions
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31
src/video_core/renderer_opengl/gl_shader_decompiler.cpp
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@ -141,6 +141,15 @@ private:
ExitMethod jmp = Scan(target, end, labels);
return exit_method = ParallelExit(no_jmp, jmp);
}
case OpCode::Id::SSY: {
// The SSY instruction uses a similar encoding as the BRA instruction.
ASSERT_MSG(instr.bra.constant_buffer == 0,
"Constant buffer SSY is not supported");
u32 target = offset + instr.bra.GetBranchTarget();
labels.insert(target);
// Continue scanning for an exit method.
break;
}
}
}
}
@ -1668,16 +1677,25 @@ private:
break;
}
case OpCode::Id::SSY: {
// The SSY opcode tells the GPU where to re-converge divergent execution paths, we
// can ignore this when generating GLSL code.
// The SSY opcode tells the GPU where to re-converge divergent execution paths, it
// sets the target of the jump that the SYNC instruction will make. The SSY opcode
// has a similar structure to the BRA opcode.
ASSERT_MSG(instr.bra.constant_buffer == 0, "Constant buffer SSY is not supported");
u32 target = offset + instr.bra.GetBranchTarget();
shader.AddLine("ssy_target = " + std::to_string(target) + "u;");
break;
}
case OpCode::Id::SYNC:
case OpCode::Id::SYNC: {
// The SYNC opcode jumps to the address previously set by the SSY opcode
ASSERT(instr.flow.cond == Tegra::Shader::FlowCondition::Always);
shader.AddLine("{ jmp_to = ssy_target; break; }");
break;
}
case OpCode::Id::DEPBAR: {
// TODO(Subv): Find out if we actually have to care about these instructions or if
// TODO(Subv): Find out if we actually have to care about this instruction or if
// the GLSL compiler takes care of that for us.
LOG_WARNING(HW_GPU, "DEPBAR/SYNC instruction is stubbed");
LOG_WARNING(HW_GPU, "DEPBAR instruction is stubbed");
break;
}
default: {
@ -1742,6 +1760,7 @@ private:
} else {
labels.insert(subroutine.begin);
shader.AddLine("uint jmp_to = " + std::to_string(subroutine.begin) + "u;");
shader.AddLine("uint ssy_target = 0u;");
shader.AddLine("while (true) {");
++shader.scope;
@ -1757,7 +1776,7 @@ private:
u32 compile_end = CompileRange(label, next_label);
if (compile_end > next_label && compile_end != PROGRAM_END) {
// This happens only when there is a label inside a IF/LOOP block
shader.AddLine("{ jmp_to = " + std::to_string(compile_end) + "u; break; }");
shader.AddLine(" jmp_to = " + std::to_string(compile_end) + "u; break; }");
labels.emplace(compile_end);
}