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Implement jump tables (#453)

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* Add 'jump_table_entry' and 'indirect_jump' instructions.

* Update CodeSink to keep track of code size. Pretty up clif-util's disassembly output.

* Only disassemble the machine portion of output. Pretty print the read-only data after it.

* Update switch frontend code to use new br_table instruction w/ default.
This commit is contained in:
Tyler McMullen
2018-10-03 11:04:21 -06:00
committed by Dan Gohman
parent de1d82b4ba
commit 79cea5e18b
39 changed files with 627 additions and 100 deletions
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7
lib/wasm/src/code_translator.rs
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@@ -283,14 +283,13 @@ pub fn translate_operator<FE: FuncEnvironment + ?Sized>(
data.push_entry(ebb);
}
let jt = builder.create_jump_table(data);
builder.ins().br_table(val, jt);
let ebb = {
let i = state.control_stack.len() - 1 - (default as usize);
let frame = &mut state.control_stack[i];
frame.set_branched_to_exit();
frame.br_destination()
};
builder.ins().jump(ebb, &[]);
builder.ins().br_table(val, ebb, jt);
} else {
// Here we have jump arguments, but Cranelift's br_table doesn't support them
// We then proceed to split the edges going out of the br_table
@@ -309,14 +308,14 @@ pub fn translate_operator<FE: FuncEnvironment + ?Sized>(
data.push_entry(branch_ebb);
}
let jt = builder.create_jump_table(data);
builder.ins().br_table(val, jt);
let default_ebb = {
let i = state.control_stack.len() - 1 - (default as usize);
let frame = &mut state.control_stack[i];
frame.set_branched_to_exit();
frame.br_destination()
};
builder.ins().jump(default_ebb, state.peekn(return_count));
dest_ebb_sequence.push((default as usize, default_ebb));
builder.ins().br_table(val, default_ebb, jt);
for (depth, dest_ebb) in dest_ebb_sequence {
builder.switch_to_block(dest_ebb);
builder.seal_block(dest_ebb);