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shader: Reorder phi nodes when redefined as undefined opcodes

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ReinUsesLisp 2021-03-17 01:33:25 -03:00 committed by ameerj
parent 8dd0acfaeb
commit 32b6c63485
1 changed files with 9 additions and 1 deletions
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10
src/shader_recompiler/ir_opt/ssa_rewrite_pass.cpp
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@ -181,8 +181,16 @@ private:
}
if (same.IsEmpty()) {
// The phi is unreachable or in the start block
const auto first_not_phi{std::ranges::find_if_not(block->Instructions(), IsPhi)};
// First remove the phi node from the block, it will be reinserted
IR::Block::InstructionList& list{block->Instructions()};
list.erase(IR::Block::InstructionList::s_iterator_to(phi));
// Insert an undef instruction after all phi nodes (to keep phi instructions on top)
const auto first_not_phi{std::ranges::find_if_not(list, IsPhi)};
same = IR::Value{&*block->PrependNewInst(first_not_phi, undef_opcode)};
// Insert the phi node after the undef opcode, this will be replaced with an identity
list.insert(first_not_phi, phi);
}
// Reroute all uses of phi to same and remove phi
phi.ReplaceUsesWith(same);