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-rw-r--r--src/mir/optimise.cpp187
1 files changed, 106 insertions, 81 deletions
diff --git a/src/mir/optimise.cpp b/src/mir/optimise.cpp
index 3b5fa036..8e350c45 100644
--- a/src/mir/optimise.cpp
+++ b/src/mir/optimise.cpp
@@ -390,6 +390,58 @@ namespace {
)
return nullptr;
}
+
+
+ void visit_blocks_mut(::MIR::TypeResolve& state, ::MIR::Function& fcn, ::std::function<void(::MIR::BasicBlockId, ::MIR::BasicBlock&)> cb)
+ {
+ ::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();
+ if( visited[bb] ) continue;
+ visited[bb] = true;
+ auto& block = fcn.blocks[bb];
+
+ cb(bb, block);
+
+ 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);
+ )
+ )
+ }
+ }
+ void visit_blocks(::MIR::TypeResolve& state, const ::MIR::Function& fcn, ::std::function<void(::MIR::BasicBlockId, const ::MIR::BasicBlock&)> cb) {
+ visit_blocks_mut(state, const_cast<::MIR::Function&>(fcn), [cb](auto id, auto& blk){ cb(id, blk); });
+ }
}
bool MIR_Optimise_BlockSimplify(::MIR::TypeResolve& state, ::MIR::Function& fcn);
@@ -398,6 +450,7 @@ bool MIR_Optimise_PropagateSingleAssignments(::MIR::TypeResolve& state, ::MIR::F
bool MIR_Optimise_UnifyTemporaries(::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);
bool MIR_Optimise_GarbageCollect_Partial(::MIR::TypeResolve& state, ::MIR::Function& fcn);
bool MIR_Optimise_GarbageCollect(::MIR::TypeResolve& state, ::MIR::Function& fcn);
@@ -445,6 +498,9 @@ void MIR_Optimise(const StaticTraitResolve& resolve, const ::HIR::ItemPath& path
// >> Combine Duplicate Blocks
change_happened |= MIR_Optimise_UnifyBlocks(state, fcn);
+ // >> Remove assignments of unsed drop flags
+ change_happened |= MIR_Optimise_DeadDropFlags(state, fcn);
+
if( change_happened )
{
#if DUMP_AFTER_PASS
@@ -2231,6 +2287,45 @@ bool MIR_Optimise_PropagateSingleAssignments(::MIR::TypeResolve& state, ::MIR::F
return replacement_happend;
}
+// ----------------------------------------
+// Clear all drop flags that are never read
+// ----------------------------------------
+bool MIR_Optimise_DeadDropFlags(::MIR::TypeResolve& state, ::MIR::Function& fcn)
+{
+ ::std::vector<bool> read_drop_flags( fcn.drop_flags.size() );
+ visit_blocks(state, fcn, [&read_drop_flags](auto , const ::MIR::BasicBlock& block) {
+ for(const auto& stmt : block.statements)
+ {
+ if( const auto* e = stmt.opt_SetDropFlag() )
+ {
+ if(e->other != ~0u) {
+ read_drop_flags[e->other] = true;
+ }
+ }
+ else if( const auto* e = stmt.opt_Drop() )
+ {
+ if(e->flag_idx != ~0u) {
+ read_drop_flags[e->flag_idx] = true;
+ }
+ }
+ }
+ });
+ bool removed_statement = false;
+ visit_blocks_mut(state, fcn, [&read_drop_flags,&removed_statement](auto _id, auto& block) {
+ for(auto it = block.statements.begin(); it != block.statements.end(); )
+ {
+ if(it->is_SetDropFlag() && ! read_drop_flags[it->as_SetDropFlag().idx] ) {
+ removed_statement = true;
+ it = block.statements.erase(it);
+ }
+ else {
+ ++ it;
+ }
+ }
+ });
+ return removed_statement;
+}
+
// --------------------------------------------------------------------
// Clear all unused blocks
@@ -2238,47 +2333,10 @@ bool MIR_Optimise_PropagateSingleAssignments(::MIR::TypeResolve& state, ::MIR::F
bool MIR_Optimise_GarbageCollect_Partial(::MIR::TypeResolve& state, ::MIR::Function& fcn)
{
::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();
- if( visited[bb] ) continue;
- 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);
- )
- )
- }
+ visit_blocks(state, fcn, [&visited](auto bb, const auto& _blokc) {
+ assert( !visited[bb] );
+ visited[bb] = true;
+ });
bool rv = false;
for(unsigned int i = 0; i < visited.size(); i ++)
{
@@ -2301,13 +2359,9 @@ bool MIR_Optimise_GarbageCollect(::MIR::TypeResolve& state, ::MIR::Function& fcn
::std::vector<bool> used_vars( fcn.named_variables.size() );
::std::vector<bool> used_dfs( fcn.drop_flags.size() );
::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();
+
+ visit_blocks(state, fcn, [&](auto bb, const auto& block) {
visited[bb] = true;
- const auto& block = fcn.blocks[bb];
auto assigned_lval = [&](const ::MIR::LValue& lv) {
if(const auto* le = lv.opt_Temporary() )
@@ -2339,40 +2393,11 @@ bool MIR_Optimise_GarbageCollect(::MIR::TypeResolve& state, ::MIR::Function& fcn
}
}
- 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);
-
- assigned_lval(e.ret_val);
- )
- )
- }
+ if( const auto* te = block.terminator.opt_Call() )
+ {
+ assigned_lval(te->ret_val);
+ }
+ });
::std::vector<unsigned int> block_rewrite_table;
for(unsigned int i = 0, j = 0; i < fcn.blocks.size(); i ++)
generated by cgit v1.2.3 (git 2.39.1) at 2024-10-30 01:56:46 +0000