Assert that labels are defined when applying label relocations #6100
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These assertions would have helped a lot with a crash that I debugged recently |
fjeremic
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Jul 12, 2021
A label has a null address until its location is determined when it is encountered in the instruction stream during binary encoding. When the compiler generates a jump to a label whose address has not yet been determined, it also generates a label relocation to correct the jump target once the label's address is known after binary encoding. But if for some reason the label's address is never updated, the relocation would silently continue using zero and generate an incorrect jump. Because such jumps can be hard to debug, this commit adds assertions that verify that the label has at least had some address set, otherwise failing fast. Note that zero cannot be the true address of a label, since we never generate instructions there.
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fjeremic
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Jul 13, 2021
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Jenkins build all |
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A label has a null address until its location is determined when it is encountered in the instruction stream during binary encoding. When the compiler generates a jump to a label whose address has not yet been determined, it also generates a label relocation to correct the jump target once the label's address is known after binary encoding. But if for some reason the label's address is never updated, the relocation would silently continue using zero and generate an incorrect jump.
Because such jumps can be hard to debug, this commit adds assertions that verify that the label has at least had some address set, otherwise failing fast. Note that zero cannot be the true address of a label, since we never generate instructions there.