1 files changed, 81 insertions, 0 deletions
diff --git a/backend/include/rcc/Tooling/MIRReducer.h b/backend/include/rcc/Tooling/MIRReducer.h
new file mode 100644
index 0000000..35ef9c0
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+++ b/backend/include/rcc/Tooling/MIRReducer.h
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_TOOLING_MIRREDUCER_H
+#define RCC_TOOLING_MIRREDUCER_H
+
+#include "rcc/Support/Error.h"
+#include "rcc/Tooling/BackendInvocation.h"
+
+#include <cstddef>
+#include <cstdint>
+#include <functional>
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace rcc {
+
+class TargetDescription;
+
+namespace tooling {
+
+enum class ReductionMode : std::uint8_t {
+  PreserveValidity,
+  PreserveFailure,
+};
+
+enum class ReductionGranularity : std::uint8_t {
+  CompilationUnit,
+  MachineFunction,
+  BasicBlock,
+  CFGEdge,
+  Instruction,
+  Operand,
+  RegisterSubgraph,
+  FrameObject,
+  ConstantPool,
+  JumpTable,
+  TargetFeature,
+  PassPipeline,
+};
+
+struct MIRReducerOptions final {
+  ReductionMode Mode = ReductionMode::PreserveFailure;
+  std::size_t MaximumAttempts = 100'000;
+  std::vector<ReductionGranularity> Granularities;
+};
+
+using MIRInterestingnessTest =
+    std::function<Expected<bool>(std::string_view, const BackendInvocation &)>;
+
+// PreserveFailure requires and evaluates the interestingness test. PreserveValidity accepts every
+// smaller candidate that reparses, canonicalizes, and verifies; its interestingness test is
+// ignored.
+
+struct MIRReductionStep final {
+  ReductionGranularity Granularity = ReductionGranularity::Instruction;
+  std::string Description;
+  std::size_t PreviousSize = 0;
+  std::size_t ReducedSize = 0;
+};
+
+struct MIRReductionResult final {
+  std::string MIR;
+  BackendInvocation Invocation;
+  std::vector<MIRReductionStep> Steps;
+  std::size_t Attempts = 0;
+  bool Exhausted = false;
+};
+
+[[nodiscard]] Expected<MIRReductionResult> reduceMIR(std::string SourceName, std::string SourceText,
+                                                     BackendInvocation Invocation,
+                                                     const TargetDescription &Target,
+                                                     const MIRInterestingnessTest &Interesting,
+                                                     MIRReducerOptions Options = {});
+
+[[nodiscard]] std::string_view spelling(ReductionGranularity Granularity) noexcept;
+
+} // namespace tooling
+} // namespace rcc
+
+#endif // RCC_TOOLING_MIRREDUCER_H