[PATCH] [lld][ARM] Add relocations to perform function calls

Rui Ueyama ruiu at google.com
Mon Feb 2 23:24:49 PST 2015

Comment at: lib/ReaderWriter/ELF/ARM/ARMRelocationHandler.cpp:35
@@ +34,3 @@
+  return result;
denis-protivensky wrote:
> denis-protivensky wrote:
> > ruiu wrote:
> > > Is this intentional that you used signed integers instead of unsigned integers in this function? I'd use uint16_t when I do bit manipulation.
> > Agreed, will update all of these places while merging.
> I just looked carefully into the code and realized that using signed integers is a proper way of handling addends, because they may be negative numbers as well.
> As for MOV addend of Thumb instruction you mentioned, it's formed from exactly 16 bits, and the value is a signed integer, which may be negative (as the reference says). So using signed integers is perfectly fine for all relocation types.
I'd think the final result type, which is a signed integer type, can be different from types used for intermediate computation. We shuffle bits by shifts and bitmasks to form a 16 bit pattern here. All intermediate types except the result can be unsigned, no? Looks like all right bit shifts in this function aren't used to extend sign bit.



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