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[RISCV] Add branch folding before branch relaxation #134760

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[RISCV] Add branch folding before branch relaxation #134760

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[RISCV] Add branch folding before branch relaxation
mikhailramalho Mar 27, 2025
47c9e17
Removed note added by update_llc_test_checks.py
mikhailramalho Apr 7, 2025
7075a8a
Merge remote-tracking branch 'origin/main' into riscv-late-opt-branch…
mikhailramalho Apr 7, 2025
515ce5b
Updated tests
mikhailramalho Apr 8, 2025
4e4ed6b
Create method to add the branch folding pass with the option to enabl…
mikhailramalho Apr 10, 2025
6afb625
Update tests
mikhailramalho Apr 10, 2025
aba8697
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mikhailramalho Apr 10, 2025
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1 change: 1 addition & 0 deletions llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
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Expand Up @@ -570,6 +570,7 @@ void RISCVPassConfig::addPreEmitPass() {
addPass(createMachineCopyPropagationPass(true));
if (TM->getOptLevel() >= CodeGenOptLevel::Default)
addPass(createRISCVLateBranchOptPass());
addPass(&BranchFolderPassID);
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@arsenm arsenm Apr 8, 2025

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It should have run already? I'd expect a "late branch opt" pass to avoid introducing new constructs that need cleanup

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@lenary lenary Apr 8, 2025

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The late branch optimisation pass is actually making it easier for branch folding to clean up things that copy propagation and other prior passes have introduced.

addPass(&BranchRelaxationPassID);
addPass(createRISCVMakeCompressibleOptPass());
}
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