Optimization: Fold redundant input parameters loads about mosa-project HOT 3 CLOSED

Plan: Insert load parameter instruction into the first block that dominates all other blocks which use the parameter. The load will move the parameter to a virtual instruction. The load instruction is placed at the end of the block, or if the block contains any existing load instruction, then immediately prior to that instruction. Replace all other load instructions with a move from the virtual instruction.

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Alternative longer-term option: Similar to before, but instead move all the load instructions to the beginning of the first block. And write another optimization stage that re-orders instructions to reduce the distance between assignments (results) and uses. The register allocator will then "best-fit" the live ranges.

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The value numbering optimization implemented this optimization and removes redundant parameter loads.

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