Printing unsigned 64-bit integers #492
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Ints in abra are 64-bit signed values, but it's also useful to treat those 64 bits as an unsigned value. There's currently no `UInt` type, because that would require a lot more logic with arithmetic and casting and dealing with overflows, but as a temporary stopgap, this introduces the `Int#unsignedToString` method (which uses `"%llu"` under the hood as the print formatter). This also updates the existing `Int#toString` implementation to use `"%lld"` (it had previously been using `"%d"`...). This also adds the `-fcall-saved-x18` flag to the flags passed to `clang` when compiling the assembly output of qbe. This is the clang version of the [`-ffixed-x18`](https://developer.arm.com/documentation/101754/0623/armclang-Reference/armclang-Command-line-Options/-ffixed-x18) flag from the arm compiler, which ensures that `x18` is preserved. Without this flag, this register can potentially be overwritten by the platform (in this case, macos) even though qbe treats it as a general-purpose register. This was the source of an extremely mysterious and frustrating bug.
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Ints in abra are 64-bit signed values, but it's also useful to treat
those 64 bits as an unsigned value. There's currently no
UInttype,because that would require a lot more logic with arithmetic and casting
and dealing with overflows, but as a temporary stopgap, this introduces
the
Int#unsignedToStringmethod (which uses"%llu"under the hood asthe print formatter). This also updates the existing
Int#toStringimplementation to use
"%lld"(it had previously been using"%d"...).This also adds the
-fcall-saved-x18flag to the flags passed toclangwhen compiling the assembly output of qbe. This is the clang version of
the
-ffixed-x18flag from the arm compiler, which ensures thatx18is preserved.Without this flag, this register can potentially be overwritten by the
platform (in this case, macos) even though qbe treats it as a
general-purpose register. This was the source of an extremely mysterious
and frustrating bug.