Don't force byte regs for indir address #16727
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This came up in the process of eliminating TreeNodeInfo (#16517). Indirections that load a byte value don't need a byte register for the address. |
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@dotnet/jit-contrib PTAL |
| @@ -754,7 +754,9 @@ void LinearScan::BuildCheckByteable(GenTree* tree) | |||
| if (tree->OperIsSimple()) | |||
| { | |||
| GenTree* op = tree->gtOp.gtOp1; | |||
| if (op != nullptr) | |||
| // We need byte registers on the operands of most simple operators that produce a byte result. | |||
| // However, indirections are simple operators but do not require their address in a byte register. | |||
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In which cases does indirection produce byte results?
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If the indirection is loading a byte from memory (e.g. a field of a struct), it will be of type byte. The register it loads into must be a byte register, but the address need not be.
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Hmm, usually an indirection of type byte/ubyte will generate a movsx/movzx instruction. In that case you don't need a byte register, the destination register is really a 32 bit register.
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