vendor/llvm/llvm-trunk-r375505vendor/llvm

1 files changed, 41 insertions, 0 deletions

diff --git a/include/llvm/CodeGen/MachineLoopUtils.h b/include/llvm/CodeGen/MachineLoopUtils.h
new file mode 100644
index 000000000000..41379b75d00a
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+++ b/include/llvm/CodeGen/MachineLoopUtils.h
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+//=- MachineLoopUtils.h - Helper functions for manipulating loops -*- C++ -*-=//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_CODEGEN_MACHINELOOPUTILS_H
+#define LLVM_LIB_CODEGEN_MACHINELOOPUTILS_H
+
+namespace llvm {
+class MachineBasicBlock;
+class MachineRegisterInfo;
+class TargetInstrInfo;
+
+enum LoopPeelDirection {
+  LPD_Front, ///< Peel the first iteration of the loop.
+  LPD_Back   ///< Peel the last iteration of the loop.
+};
+
+/// Peels a single block loop. Loop must have two successors, one of which
+/// must be itself. Similarly it must have two predecessors, one of which must
+/// be itself.
+///
+/// The loop block is copied and inserted into the CFG such that two copies of
+/// the loop follow on from each other. The copy is inserted either before or
+/// after the loop based on Direction.
+///
+/// Phis are updated and an unconditional branch inserted at the end of the
+/// clone so as to execute a single iteration.
+///
+/// The trip count of Loop is not updated.
+MachineBasicBlock *PeelSingleBlockLoop(LoopPeelDirection Direction,
+                                       MachineBasicBlock *Loop,
+                                       MachineRegisterInfo &MRI,
+                                       const TargetInstrInfo *TII);
+
+} // namespace llvm
+
+#endif // LLVM_LIB_CODEGEN_MACHINELOOPUTILS_H