diff options
| -rw-r--r-- | src/mir/mir.cpp | 33 | ||||
| -rw-r--r-- | src/mir/mir.hpp | 4 | ||||
| -rw-r--r-- | src/mir/optimise.cpp | 70 |
3 files changed, 107 insertions, 0 deletions
diff --git a/src/mir/mir.cpp b/src/mir/mir.cpp index 18557304..fb34357e 100644 --- a/src/mir/mir.cpp +++ b/src/mir/mir.cpp @@ -500,6 +500,39 @@ namespace MIR { ) return os; } + bool operator==(const Statement& a, const Statement& b) { + if( a.tag() != b.tag() ) + return false; + + TU_MATCHA( (a,b), (ae,be), + (Assign, + return ae.dst == be.dst && ae.src == be.src; + ), + (Asm, + return ae.outputs == be.outputs + && ae.inputs == be.inputs + && ae.clobbers == be.clobbers + && ae.flags == be.flags + ; + ), + (SetDropFlag, + return ae.idx == be.idx + && ae.other == be.other + && ae.new_val == be.new_val + ; + ), + (Drop, + return ae.slot == be.slot + && ae.kind == be.kind + && ae.flag_idx == be.flag_idx + ; + ), + (ScopeEnd, + return ae.slots == be.slots; + ) + ) + throw ""; + } } ::MIR::LValue MIR::LValue::clone() const diff --git a/src/mir/mir.hpp b/src/mir/mir.hpp index 3ce115b8..2a623d3c 100644 --- a/src/mir/mir.hpp +++ b/src/mir/mir.hpp @@ -285,6 +285,10 @@ TAGGED_UNION(Statement, Assign, }) ); extern ::std::ostream& operator<<(::std::ostream& os, const Statement& x); +extern bool operator==(const Statement& a, const Statement& b); +static inline bool operator!=(const Statement& a, const Statement& b) { + return !(a == b); +} struct BasicBlock { diff --git a/src/mir/optimise.cpp b/src/mir/optimise.cpp index 9935454e..4c2da555 100644 --- a/src/mir/optimise.cpp +++ b/src/mir/optimise.cpp @@ -498,6 +498,7 @@ bool MIR_Optimise_PropagateSingleAssignments(::MIR::TypeResolve& state, ::MIR::F bool MIR_Optimise_PropagateKnownValues(::MIR::TypeResolve& state, ::MIR::Function& fcn); bool MIR_Optimise_DeTemporary(::MIR::TypeResolve& state, ::MIR::Function& fcn); // Eliminate useless temporaries bool MIR_Optimise_UnifyTemporaries(::MIR::TypeResolve& state, ::MIR::Function& fcn); +bool MIR_Optimise_CommonStatements(::MIR::TypeResolve& state, ::MIR::Function& fcn); bool MIR_Optimise_UnifyBlocks(::MIR::TypeResolve& state, ::MIR::Function& fcn); bool MIR_Optimise_ConstPropagte(::MIR::TypeResolve& state, ::MIR::Function& fcn); bool MIR_Optimise_DeadDropFlags(::MIR::TypeResolve& state, ::MIR::Function& fcn); @@ -600,6 +601,9 @@ void MIR_Optimise(const StaticTraitResolve& resolve, const ::HIR::ItemPath& path } #endif + // >> Move common statements (assignments) across gotos. + change_happened |= MIR_Optimise_CommonStatements(state, fcn); + // >> Combine Duplicate Blocks change_happened |= MIR_Optimise_UnifyBlocks(state, fcn); // >> Remove assignments of unsed drop flags @@ -1431,6 +1435,72 @@ bool MIR_Optimise_DeTemporary(::MIR::TypeResolve& state, ::MIR::Function& fcn) return changed; } + +// -------------------------------------------------------------------- +// Detect common statements between all source arms of a block +// -------------------------------------------------------------------- +bool MIR_Optimise_CommonStatements(::MIR::TypeResolve& state, ::MIR::Function& fcn) +{ + bool changed = false; + TRACE_FUNCTION_FR("", changed); + + for(size_t bb_idx = 0; bb_idx < fcn.blocks.size(); bb_idx ++) + { + state.set_cur_stmt(bb_idx, 0); + + bool skip = false; + ::std::vector<size_t> sources; + // Find source blocks + for(size_t bb2_idx = 0; bb2_idx < fcn.blocks.size(); bb2_idx ++) + { + const auto& blk = fcn.blocks[bb2_idx]; + // TODO: Handle non-Goto branches? (e.g. calls) + if( blk.terminator.is_Goto() && blk.terminator.as_Goto() == bb_idx ) + { + if( blk.statements.empty() ) + { + DEBUG(state << " BB" << bb2_idx << " empty"); + skip = true; + break ; + } + if( !sources.empty() ) + { + if( blk.statements.back() != fcn.blocks[sources.front()].statements.back() ) + { + DEBUG(state << " BB" << bb2_idx << " doesn't end with " << fcn.blocks[sources.front()].statements.back() << " instead " << blk.statements.back()); + skip = true; + break; + } + } + sources.push_back(bb2_idx); + } + else + { + visit_terminator_target(blk.terminator, [&](const auto& dst_idx) { + if( dst_idx == bb_idx ) { + DEBUG(state << " BB" << bb2_idx << " doesn't end Goto - instead " << blk.terminator); + skip = true; + } + }); + } + } + + if( !skip && sources.size() > 1 ) + { + // Found a common assignment, add to the start and remove from sources. + auto stmt = ::std::move(fcn.blocks[sources.front()].statements.back()); + MIR_DEBUG(state, "Move common final statements from " << sources << " to " << bb_idx << " - " << stmt); + for(auto idx : sources) + { + fcn.blocks[idx].statements.pop_back(); + } + fcn.blocks[bb_idx].statements.insert(fcn.blocks[bb_idx].statements.begin(), ::std::move(stmt)); + } + } + return changed; +} + + // -------------------------------------------------------------------- // If two temporaries don't overlap in lifetime (blocks in which they're valid), unify the two // -------------------------------------------------------------------- |