Initial bringup for Linux/Thumb2 #8683
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Pointer types need an extra indirection layer during the generation of the function prototype for inline asm blocks. Closes ziglang#3606
To be honest all this detection logic is starting to become a real PITA, the ARM32 version can be possibly removed as the generic version optimizes pretty well...
There are some small problems here and there, mostly due to the pointers having the lsb set and disrupting the fn alignment tests and the `@FrameSize` implementation.
andrewrk
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May 5, 2021
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| // XXX What do we do if the target has the noarm feature? | ||
| // What do we do if the user specifies +thumb_mode? |
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The fundamental problem here is that we have multiple different ways of representing the same state.
Let's try to eliminate redundancies. Here are some (breaking) ideas:
- Remove the thumb sub-architecture in favor of the
thumb_modeCPU feature. Instead of-target thumb-linuxit would be-target arm-linux -mcpu=generic+v7m - Delete the
noarmCPU feature since it appears to be completely redundant withthumb_mode. All feature sets that includethumb_modealso includenoarm.- we would probably still need to emit
noarmwhen lowering thumb_mode cpu features to LLVM
- we would probably still need to emit
After a few minutes considering this I think I would be in favor of both these ideas.
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The former makes more sense, noarm is effectively a CPU feature that signals no interworking is possible at all.
Clang takes a similar approach and requires -mthumb or -mno-thumb to be specified, that's another possible solution to take into account.
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@andrewrk I'd love your input on the XXX comment in
system.zig