81251c3005
Compute exact EBB header offsets and check that branches are in range. Not implemented yet: Relax branches that are not in range. Invoke the relax_branches() pass from the 'test binemit' file tests so they can verify the proper encoding of branch instructions too.
58 lines
1.7 KiB
Rust
58 lines
1.7 KiB
Rust
//! Binary machine code emission.
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//!
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//! The `binemit` module contains code for translating Cretonne's intermediate representation into
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//! binary machine code.
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mod relaxation;
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pub use self::relaxation::relax_branches;
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use ir::{Ebb, FuncRef, JumpTable, Function, Inst};
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/// Offset in bytes from the beginning of the function.
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///
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/// Cretonne can be used as a cross compiler, so we don't want to use a type like `usize` which
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/// depends on the *host* platform, not the *target* platform.
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pub type CodeOffset = u32;
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/// Relocation kinds depend on the current ISA.
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pub struct Reloc(pub u16);
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/// Abstract interface for adding bytes to the code segment.
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///
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/// A `CodeSink` will receive all of the machine code for a function. It also accepts relocations
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/// which are locations in the code section that need to be fixed up when linking.
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pub trait CodeSink {
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/// Get the current position.
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fn offset(&self) -> CodeOffset;
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/// Add 1 byte to the code section.
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fn put1(&mut self, u8);
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/// Add 2 bytes to the code section.
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fn put2(&mut self, u16);
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/// Add 4 bytes to the code section.
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fn put4(&mut self, u32);
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/// Add 8 bytes to the code section.
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fn put8(&mut self, u64);
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/// Add a relocation referencing an EBB at the current offset.
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fn reloc_ebb(&mut self, Reloc, Ebb);
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/// Add a relocation referencing an external function at the current offset.
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fn reloc_func(&mut self, Reloc, FuncRef);
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/// Add a relocation referencing a jump table.
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fn reloc_jt(&mut self, Reloc, JumpTable);
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}
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/// Report a bad encoding error.
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#[inline(never)]
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pub fn bad_encoding(func: &Function, inst: Inst) -> ! {
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panic!("Bad encoding {} for {}",
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func.encodings[inst],
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func.dfg.display_inst(inst));
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}
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