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48 lines
2.2 KiB
48 lines
2.2 KiB
// Copyright (c) 2014 Daniel Grunwald |
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// |
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// Permission is hereby granted, free of charge, to any person obtaining a copy of this |
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// software and associated documentation files (the "Software"), to deal in the Software |
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// without restriction, including without limitation the rights to use, copy, modify, merge, |
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// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons |
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// to whom the Software is furnished to do so, subject to the following conditions: |
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// |
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// The above copyright notice and this permission notice shall be included in all copies or |
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// substantial portions of the Software. |
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// |
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, |
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// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR |
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// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE |
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// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR |
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// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
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// DEALINGS IN THE SOFTWARE. |
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using System; |
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namespace ICSharpCode.Decompiler.IL |
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{ |
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static class SemanticHelper |
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{ |
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/// <summary> |
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/// Gets whether the instruction sequence 'inst1; inst2;' may be ordered to 'inst2; inst1;' |
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/// </summary> |
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internal static bool MayReorder(InstructionFlags inst1, InstructionFlags inst2) |
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{ |
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// If both instructions perform a non-read-only action, we cannot reorder them |
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if ((inst1 & inst2 & ~(InstructionFlags.MayPeek | InstructionFlags.MayReadLocals)) != 0) |
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return false; |
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// We cannot reorder if inst2 might pop what inst1 peeks at |
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if (ConflictingPair(inst1, inst2, InstructionFlags.MayPeek, InstructionFlags.MayPop)) |
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return false; |
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if (ConflictingPair(inst1, inst2, InstructionFlags.MayReadLocals, InstructionFlags.MayWriteLocals)) |
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return false; |
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return true; |
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} |
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private static bool ConflictingPair(InstructionFlags inst1, InstructionFlags inst2, InstructionFlags readFlag, InstructionFlags writeFlag) |
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{ |
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// if one instruction has the read flag and the other the write flag, that's a conflict |
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return (inst1 & readFlag) != 0 && (inst2 & writeFlag) != 0 |
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|| (inst2 & readFlag) != 0 && (inst1 & writeFlag) != 0; |
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} |
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} |
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} |