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| author | John Hodge <tpg@ucc.asn.au> | 2017-12-02 08:32:23 +0800 |
|---|---|---|
| committer | John Hodge <tpg@ucc.asn.au> | 2017-12-02 08:32:23 +0800 |
| commit | 1887d94d65bb38624f03944597662244a92cfd80 (patch) | |
| tree | 8e79f0896b51cb104995ea58f03c5614ba4cccf2 /src | |
| parent | b590a2adb49ba146aa2d866af4e47c7d9427acf0 (diff) | |
| download | mrust-1887d94d65bb38624f03944597662244a92cfd80.tar.gz | |
MIR Optimise - Fix infinite replacement
Diffstat (limited to 'src')
| -rw-r--r-- | src/mir/optimise.cpp | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/src/mir/optimise.cpp b/src/mir/optimise.cpp index 00ad19b0..e83f0ee1 100644 --- a/src/mir/optimise.cpp +++ b/src/mir/optimise.cpp @@ -62,6 +62,7 @@ namespace { bool visit_mir_lvalue_mut(::MIR::LValue& lv, ValUsage u, ::std::function<bool(::MIR::LValue& , ValUsage)> cb) { + //TRACE_FUNCTION_F(lv); if( cb(lv, u) ) return true; TU_MATCHA( (lv), (e), @@ -553,12 +554,14 @@ void MIR_Optimise(const StaticTraitResolve& resolve, const ::HIR::ItemPath& path MIR_Validate(resolve, path, fcn, args, ret_type); #endif +#if 1 // Attempt to remove useless temporaries while( MIR_Optimise_DeTemporary(state, fcn) ) change_happened = true; #if CHECK_AFTER_ALL MIR_Validate(resolve, path, fcn, args, ret_type); #endif +#endif // >> Replace values from composites if they're known // - Undoes the inefficiencies from the `match (a, b) { ... }` pattern @@ -1305,6 +1308,7 @@ bool MIR_Optimise_DeTemporary(::MIR::TypeResolve& state, ::MIR::Function& fcn) } lv = mv$(new_lv); changed = true; + return true; } } return false; @@ -1337,11 +1341,18 @@ bool MIR_Optimise_DeTemporary(::MIR::TypeResolve& state, ::MIR::Function& fcn) { to_add = ::std::make_pair(e->dst.as_Local(), stmt_idx); something_to_add = true; + + if( visit_mir_lvalues(e->src, [&](const auto& lv, auto ){ return lv == e->dst; }) ) + { + DEBUG(state << "Assignment to slot used in source, can't use"); + something_to_add = false; + } } local_assignments.erase( e->dst.as_Local() ); } check_invalidates(e->dst); + // Remove no-op assignents if( TU_TEST1(e->src, Use, == e->dst) ) { bb.statements.erase(bb.statements.begin() + stmt_idx); stmt_idx -= 1; |