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Limit redundant jump folding to only fold parameterless target blocks (#972)

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This commit is contained in:
Sean Stangl
2019-09-05 08:21:29 -06:00
committed by GitHub
parent ea919489ee
commit 26b88ae7b5
1 changed files with 8 additions and 0 deletions
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8
cranelift/codegen/src/binemit/relaxation.rs
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@@ -169,6 +169,14 @@ fn try_fold_redundant_jump(
} }
}; };
// For the moment, only attempt to fold a branch to an ebb that is parameterless.
// These blocks are mainly produced by critical edge splitting.
//
// TODO: Allow folding blocks that define SSA values and function as phi nodes.
if func.dfg.num_ebb_params(first_dest) != 0 {
return false;
}
// Look at the first instruction of the first branch's destination. // Look at the first instruction of the first branch's destination.
// If it is an unconditional branch, maybe the second jump can be bypassed. // If it is an unconditional branch, maybe the second jump can be bypassed.
let second_inst = func.layout.first_inst(first_dest).expect("Instructions"); let second_inst = func.layout.first_inst(first_dest).expect("Instructions");