asm: add support for noreturn option #717
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OpUnreachable will be appended as terminator at the end of the asm block.
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With options(noreturn), the user should not have to write %unused = OpLabel, which is quite a horrible workaround hack.
I believe the proper fix here is to add full understanding of basic blocks to the asm emitter, rather than shoving basic block headers/terminators into blocks[i].instructions.
Specifically, the emitter should keep track of whether the current context is within a basic block, keep track of what that block is (if there is a block), validate that no invalidly placed instructions are present (e.g. OpAdd after a terminator), and assert that at the end of the block, if noreturn is not present, there is an active block, but if noreturn is present, there is not an active block.
I tried to incorporate the suggested approach. Please have a look again! |
| @@ -328,10 +366,32 @@ impl<'cx, 'tcx> Builder<'cx, 'tcx> { | |||
| } | |||
| return; | |||
| } | |||
| _ => { | |||
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| op => { | |||
| self.emit() | |||
| .insert_into_block(dr::InsertPoint::End, inst) | |||
| .unwrap(); | |||
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Still would be nice to not shove everything into the same block, including terminators and labels, but whatever I guess!
OpUnreachablewill be appended as terminator at the end of the asm block (done automatically by the rustc)Fixes #570