llvm-project

80831832 - [compiler-rt][ARM] Double-precision FP support functions (#179920)

[compiler-rt][ARM] Double-precision FP support functions (#179920) This commit adds C helper functions `dnan2`, `dnorm2` and `dunder` for handling the less critical edge cases of double-precision arithmetic, similar to `fnan2`, `fnorm2` and `funder` that were added in commit f7e652127772e93. It also adds a header file that defines some register aliases for handling double-precision numbers in AArch32 software floating point in an endianness-independent way, by providing aliases `xh` and `xl` for the high and low words of the first double-precision function argument, regardless of which of them is in r0 and which in r1, and similarly `yh` and `yl` for the second argument in r2/r3.