glasm: Add GLASM backend infrastructure

src/shader_recompiler/backend/glasm/reg_alloc.cpp

@@ -0,0 +1,82 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <string>
+#include <string_view>
+
+#include <fmt/format.h>
+
+#include "shader_recompiler/backend/glasm/reg_alloc.h"
+#include "shader_recompiler/exception.h"
+#include "shader_recompiler/frontend/ir/value.h"
+
+namespace Shader::Backend::GLASM {
+namespace {
+constexpr std::string_view SWIZZLE = "xyzw";
+
+std::string Representation(Id id) {
+    if (id.is_condition_code != 0) {
+        throw NotImplementedException("Condition code");
+    }
+    if (id.is_spill != 0) {
+        throw NotImplementedException("Spilling");
+    }
+    const u32 num_elements{id.num_elements_minus_one + 1};
+    const u32 index{static_cast<u32>(id.index)};
+    if (num_elements == 4) {
+        return fmt::format("R{}", index);
+    } else {
+        return fmt::format("R{}.{}", index, SWIZZLE.substr(id.base_element, num_elements));
+    }
+}
+} // Anonymous namespace
+
+std::string RegAlloc::Define(IR::Inst& inst, u32 num_elements, u32 alignment) {
+    const Id id{Alloc(num_elements, alignment)};
+    inst.SetDefinition<Id>(id);
+    return Representation(id);
+}
+
+std::string RegAlloc::Consume(const IR::Value& value) {
+    if (!value.IsImmediate()) {
+        return Consume(*value.Inst());
+    }
+    throw NotImplementedException("Immediate loading");
+}
+
+std::string RegAlloc::Consume(IR::Inst& inst) {
+    const Id id{inst.Definition<Id>()};
+    inst.DestructiveRemoveUsage();
+    if (!inst.HasUses()) {
+        Free(id);
+    }
+    return Representation(inst.Definition<Id>());
+}
+
+Id RegAlloc::Alloc(u32 num_elements, [[maybe_unused]] u32 alignment) {
+    for (size_t reg = 0; reg < NUM_REGS; ++reg) {
+        if (register_use[reg]) {
+            continue;
+        }
+        num_used_registers = std::max(num_used_registers, reg + 1);
+        register_use[reg] = true;
+        return Id{
+            .base_element = 0,
+            .num_elements_minus_one = num_elements - 1,
+            .index = static_cast<u32>(reg),
+            .is_spill = 0,
+            .is_condition_code = 0,
+        };
+    }
+    throw NotImplementedException("Register spilling");
+}
+
+void RegAlloc::Free(Id id) {
+    if (id.is_spill != 0) {
+        throw NotImplementedException("Free spill");
+    }
+    register_use[id.index] = false;
+}
+
+} // namespace Shader::Backend::GLASM