vasm-graph-color: split penalty vectors when consensus conflicts #9686
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color_block_initialize() biases each live-in toward the phys reg that its processed predecessors already use by adding weight to every *other* phys reg in the shared penalty vector. When multiple live-ins reuse that vector but their predecessors chose different phys regs, those penalties contradict each other. The resulting vector no longer corresponds to any of the prior assignments, so the allocator picks a register based on whatever mix of penalties remains, and we emit edge copies to fix the mismatches (while also pushing the wrong hint backward). Detect conflicting consensus assignments and clone the penalty vector on the spot so each live-in keeps its own bias/undo bookkeeping.
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Thanks again for the PR! This one triggers an assertion We also get SIGABRT crashes (e.g |
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color_block_initialize() biases each live-in toward the phys reg that its processed predecessors already use by adding weight to every other phys reg in the shared penalty vector. When multiple live-ins reuse that vector but their predecessors chose different phys regs, those penalties contradict each other. The resulting vector no longer corresponds to any of the prior assignments, so the allocator picks a register based on whatever mix of penalties remains, and we emit edge copies to fix the mismatches (while also pushing the wrong hint backward).
Detect conflicting consensus assignments and clone the penalty vector on the spot so each live-in keeps its own bias/undo bookkeeping.