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Diffstat (limited to 'src/mir/optimise.cpp')
| -rw-r--r-- | src/mir/optimise.cpp | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/src/mir/optimise.cpp b/src/mir/optimise.cpp new file mode 100644 index 00000000..72651dd3 --- /dev/null +++ b/src/mir/optimise.cpp @@ -0,0 +1,177 @@ +/* + * MRustC - Rust Compiler + * - By John Hodge (Mutabah/thePowersGang) + * + * mir/optimise.cpp + * - MIR Optimisations + * + */ +#include "main_bindings.hpp" +#include "mir.hpp" +#include <hir/visitor.hpp> +#include <hir_typeck/static.hpp> +#include <mir/helpers.hpp> +#include <mir/operations.hpp> + +namespace { + ::MIR::BasicBlockId get_new_target(const ::MIR::TypeResolve& state, ::MIR::BasicBlockId bb) + { + const auto& target = state.get_block(bb); + if( target.statements.size() != 0 ) + { + return bb; + } + else if( !target.terminator.is_Goto() ) + { + return bb; + } + else + { + // Make sure we don't infinite loop + if( bb == target.terminator.as_Goto() ) + return bb; + + auto rv = get_new_target(state, target.terminator.as_Goto()); + DEBUG(bb << " => " << rv); + return rv; + } + } +} + +void MIR_Optimise(const StaticTraitResolve& resolve, const ::HIR::ItemPath& path, ::MIR::Function& fcn, const ::HIR::Function::args_t& args, const ::HIR::TypeRef& ret_type) +{ + static Span sp; + TRACE_FUNCTION_F(path); + ::MIR::TypeResolve state { sp, resolve, FMT_CB(ss, ss << path;), ret_type, args, fcn }; + + // 1. Replace targets that point to a block that is just a goto + for(auto& block : fcn.blocks) + { + TU_MATCHA( (block.terminator), (e), + (Incomplete, + ), + (Return, + ), + (Diverge, + ), + (Goto, + e = get_new_target(state, e); + ), + (Panic, + ), + (If, + e.bb0 = get_new_target(state, e.bb0); + e.bb1 = get_new_target(state, e.bb1); + ), + (Switch, + for(auto& target : e.targets) + target = get_new_target(state, target); + ), + (Call, + e.ret_block = get_new_target(state, e.ret_block); + e.panic_block = get_new_target(state, e.panic_block); + ) + ) + } + + #if 0 + // GC pass on blocks and variables + // - Find unused blocks, then delete and rewrite all references. + { + ::std::vector<bool> visited( fcn.blocks.size() ); + ::std::vector< ::MIR::BasicBlockId> to_visit; + to_visit.push_back( 0 ); + while( to_visit.size() > 0 ) + { + auto bb = to_visit.back(); to_visit.pop_back(); + visited[bb] = true; + + const auto& block = fcn.blocks[bb]; + TU_MATCHA( (block.terminator), (e), + (Incomplete, + ), + (Return, + ), + (Diverge, + ), + (Goto, + if( !visited[e] ) + to_visit.push_back(e); + ), + (Panic, + ), + (If, + if( !visited[e.bb0] ) + to_visit.push_back(e.bb0); + if( !visited[e.bb1] ) + to_visit.push_back(e.bb1); + ), + (Switch, + for(auto& target : e.targets) + if( !visited[target] ) + to_visit.push_back(target); + ), + (Call, + if( !visited[e.ret_block] ) + to_visit.push_back(e.ret_block); + if( !visited[e.panic_block] ) + to_visit.push_back(e.panic_block); + ) + ) + } + + ::std::vector<unsigned int> rewrite_table; + for(unsigned int i = 0, j = 0; i < fcn.blocks.size(); i ++) + { + if( visited[i] ) { + rewrite_table.push_back(j++); + } + else { + rewrite_table.push_back(~0u); + } + } + + auto it = fcn.blocks.begin(); + for(unsigned int i = 0; i < visited.size(); i ++) + { + if( !visited[i] ) + { + // Delete + DEBUG("GC bb" << i); + it = fcn.blocks.erase(it); + } + else + { + // Rewrite and advance + TU_MATCHA( (it->terminator), (e), + (Incomplete, + ), + (Return, + ), + (Diverge, + ), + (Goto, + e = rewrite_table[e]; + ), + (Panic, + ), + (If, + e.bb0 = rewrite_table[e.bb0]; + e.bb1 = rewrite_table[e.bb1]; + ), + (Switch, + for(auto& target : e.targets) + target = rewrite_table[target]; + ), + (Call, + e.ret_block = rewrite_table[e.ret_block]; + e.panic_block = rewrite_table[e.panic_block]; + ) + ) + + ++it; + } + } + } + #endif +} |