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970c019d02
This is a minor improvement in the ELFv2 ABI. In ELFv1, DWARF CFI would represent a saved CR word (holding CR fields CR2, CR3, and CR4) using just a single CFI record refering to CR2. In ELFv2 instead, each of the CR fields is represented by its own CFI record. The advantage is that the compiler can now chose to save just a single (or two) CR fields instead of all of them, if those are the only ones that actually need saving. That can lead to more efficient code using mf(o)crf instead of the (slow) mfcr instruction. Note that this patch does not (yet) implement this more efficient code generation, but it does implement the part that is required to be ABI compliant: creating multiple CFI records if multiple CR fields are saved. Reviewed by Hal Finkel. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213492 91177308-0d34-0410-b5e6-96231b3b80d8
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