optimization of scripting idioms - min/max, has-elements

src/Expr.h

@@ -883,6 +883,9 @@ public:
 protected:
     void ExprDescribe(ODesc* d) const override;
 
+    bool IsMinOrMax(Reducer* c) const;
+    ExprPtr TransformToMinOrMax() const;
+
     ExprPtr op1;
     ExprPtr op2;
     ExprPtr op3;

src/Stmt.h

@@ -128,6 +128,9 @@ protected:
     ValPtr DoExec(Frame* f, Val* v, StmtFlowType& flow) override;
     bool IsPure() const override;
 
+    bool IsMinMaxConstruct() const;
+    StmtPtr ConvertToMinMaxConstruct();
+
     StmtPtr s1;
     StmtPtr s2;
 };

src/script_opt/Stmt.cc

@@ -166,7 +166,7 @@ void IfStmt::Inline(Inliner* inl) {
 }
 
 bool IfStmt::IsReduced(Reducer* c) const {
-    if ( e->IsConst() || ! e->IsReducedConditional(c) )
+    if ( e->IsConst() || ! e->IsReducedConditional(c) || IsMinMaxConstruct() )
         return NonReduced(e.get());
 
     return s1->IsReduced(c) && s2->IsReduced(c);
@@ -179,11 +179,11 @@ StmtPtr IfStmt::DoReduce(Reducer* c) {
         e = e->ReduceToConditional(c, red_e_stmt);
 
     // First, assess some fundamental transformations.
-    if ( e->Tag() == EXPR_NOT ) { // Change "if ( ! x ) s1 else s2" to "if ( x ) s2 else s1".
-        auto s1_orig = s1;
-        s1 = s2;
-        s2 = s1_orig;
+    if ( IsMinMaxConstruct() )
+        return ConvertToMinMaxConstruct()->Reduce(c);
 
+    if ( e->Tag() == EXPR_NOT ) { // Change "if ( ! x ) s1 else s2" to "if ( x ) s2 else s1".
+        std::swap(s1, s2);
         e = e->GetOp1();
     }
 
@@ -274,6 +274,81 @@ bool IfStmt::CouldReturn(bool ignore_break) const {
     return (s1 && s1->CouldReturn(ignore_break)) || (s2 && s2->CouldReturn(ignore_break));
 }
 
+bool IfStmt::IsMinMaxConstruct() const {
+    if ( ! s1 || ! s2 )
+        // not an if-else construct
+        return false;
+
+    if ( s1->Tag() != STMT_EXPR || s2->Tag() != STMT_EXPR )
+        // definitely not if-else assignments
+        return false;
+
+    auto es1 = s1->AsExprStmt()->StmtExpr();
+    auto es2 = s2->AsExprStmt()->StmtExpr();
+
+    if ( es1->Tag() != EXPR_ASSIGN || es2->Tag() != EXPR_ASSIGN )
+        return false;
+
+    switch ( e->Tag() ) {
+        case EXPR_LT:
+        case EXPR_LE:
+        case EXPR_GE:
+        case EXPR_GT: break;
+
+        default:
+            // Not an apt conditional.
+            return false;
+    }
+
+    auto a1 = es1->AsAssignExpr();
+    auto a2 = es2->AsAssignExpr();
+    auto a1_lhs = a1->GetOp1();
+    auto a2_lhs = a2->GetOp1();
+
+    if ( ! same_expr(a1_lhs, a2_lhs) )
+        // if-else assignments are not to the same variable
+        return false;
+
+    auto a1_rhs = a1->GetOp2();
+    auto a2_rhs = a2->GetOp2();
+    auto op1 = e->GetOp1();
+    auto op2 = e->GetOp2();
+
+    if ( ! same_expr(op1, a1_rhs) && ! same_expr(op1, a2_rhs) )
+        // Operand does not appear in the assignment RHS.
+        return false;
+
+    if ( ! same_expr(op2, a1_rhs) && ! same_expr(op2, a2_rhs) )
+        // Operand does not appear in the assignment RHS.
+        return false;
+
+    if ( same_expr(op1, op2) )
+        // This is degenerate and should be found by other reductions.
+        return false;
+
+    return true;
+}
+
+StmtPtr IfStmt::ConvertToMinMaxConstruct() {
+    auto relop1 = e->GetOp1();
+    auto relop2 = e->GetOp2();
+
+    auto is_min = (e->Tag() == EXPR_LT || e->Tag() == EXPR_LE);
+    auto assign2 = s2->AsExprStmt()->StmtExpr();
+    auto lhs2 = assign2->GetOp1();
+    auto rhs2 = assign2->GetOp2();
+
+    if ( same_expr(relop1, rhs2) )
+        is_min = ! is_min;
+
+    auto built_in = is_min ? ScriptOptBuiltinExpr::MINIMUM : ScriptOptBuiltinExpr::MAXIMUM;
+
+    auto bi = with_location_of(make_intrusive<ScriptOptBuiltinExpr>(built_in, relop1, relop2), this);
+    auto new_assign = with_location_of(make_intrusive<AssignExpr>(lhs2, bi, false), this);
+
+    return with_location_of(make_intrusive<ExprStmt>(new_assign), this);
+}
+
 IntrusivePtr<Case> Case::Duplicate() {
     if ( expr_cases ) {
         auto new_exprs = expr_cases->Duplicate()->AsListExprPtr();

src/script_opt/ZAM/Expr.cc

@@ -4,6 +4,7 @@
 
 #include "zeek/Desc.h"
 #include "zeek/Reporter.h"
+#include "zeek/script_opt/ZAM/BuiltIn.h"
 #include "zeek/script_opt/ZAM/Compile.h"
 
 namespace zeek::detail {
@@ -134,8 +135,12 @@ const ZAMStmt ZAMCompiler::CompileAssignExpr(const AssignExpr* e) {
     auto op2 = e->GetOp2();
 
     auto lhs = op1->AsRefExpr()->GetOp1()->AsNameExpr();
-    auto lt = lhs->GetType().get();
     auto rhs = op2.get();
+
+    if ( rhs->Tag() == EXPR_SCRIPT_OPT_BUILTIN )
+        return CompileZAMBuiltin(lhs, static_cast<const ScriptOptBuiltinExpr*>(rhs));
+
+    auto lt = lhs->GetType().get();
     auto r1 = rhs->GetOp1();
 
     if ( rhs->Tag() == EXPR_INDEX && (r1->Tag() == EXPR_NAME || r1->Tag() == EXPR_CONST) )
@@ -178,8 +183,10 @@ const ZAMStmt ZAMCompiler::CompileAssignExpr(const AssignExpr* e) {
         return L_In_VecVLC(lhs, r1->AsListExpr(), r2c);
     }
 
-    if ( rhs->Tag() == EXPR_ANY_INDEX )
-        return AnyIndexVVi(lhs, r1->AsNameExpr(), rhs->AsAnyIndexExpr()->Index());
+    if ( rhs->Tag() == EXPR_ANY_INDEX ) {
+        auto rhs_as_any = static_cast<const AnyIndexExpr*>(rhs);
+        return AnyIndexVVi(lhs, r1->AsNameExpr(), rhs_as_any->Index());
+    }
 
     if ( rhs->Tag() == EXPR_LAMBDA )
         return BuildLambda(lhs, rhs->AsLambdaExpr());
@@ -220,6 +227,72 @@ const ZAMStmt ZAMCompiler::CompileAssignExpr(const AssignExpr* e) {
 #include "ZAM-GenExprsDefsV.h"
 }
 
+const ZAMStmt ZAMCompiler::CompileZAMBuiltin(const NameExpr* lhs, const ScriptOptBuiltinExpr* zbi) {
+    auto op1 = zbi->GetOp1();
+    auto op2 = zbi->GetOp2();
+
+    switch ( zbi->Tag() ) {
+        case ScriptOptBuiltinExpr::MINIMUM:
+        case ScriptOptBuiltinExpr::MAXIMUM: {
+            auto t1 = op1->GetType()->InternalType();
+            ASSERT(t1 == op2->GetType()->InternalType());
+
+            bool is_min = zbi->Tag() == ScriptOptBuiltinExpr::MINIMUM;
+            // Canonicalize to have constant as second op.
+            if ( op1->Tag() == EXPR_CONST ) {
+                ASSERT(op2->Tag() != EXPR_CONST);
+                std::swap(op1, op2);
+                is_min = ! is_min;
+            }
+
+            ZOp op;
+
+            auto n1 = op1->AsNameExpr();
+            auto n2 = op2->Tag() == EXPR_NAME ? op2->AsNameExpr() : nullptr;
+            auto c = op2->Tag() == EXPR_CONST ? op2->AsConstExpr() : nullptr;
+
+            if ( c ) {
+                if ( t1 == TYPE_INTERNAL_UNSIGNED )
+                    op = is_min ? OP_MINU_VVC : OP_MAXU_VVC;
+                else if ( t1 == TYPE_INTERNAL_INT )
+                    op = is_min ? OP_MINI_VVC : OP_MAXI_VVC;
+                else {
+                    ASSERT(t1 == TYPE_INTERNAL_DOUBLE);
+                    op = is_min ? OP_MIND_VVC : OP_MAXD_VVC;
+                }
+            }
+            else {
+                if ( t1 == TYPE_INTERNAL_UNSIGNED )
+                    op = is_min ? OP_MINU_VVV : OP_MAXU_VVV;
+                else if ( t1 == TYPE_INTERNAL_INT )
+                    op = is_min ? OP_MINI_VVV : OP_MAXI_VVV;
+                else {
+                    ASSERT(t1 == TYPE_INTERNAL_DOUBLE);
+                    op = is_min ? OP_MIND_VVV : OP_MAXD_VVV;
+                }
+            }
+
+            if ( c )
+                return AddInst(GenInst(op, lhs, n1, c));
+            else
+                return AddInst(GenInst(op, lhs, n1, n2));
+        }
+
+        case ScriptOptBuiltinExpr::HAS_ELEMENTS: {
+            auto n = op1->AsNameExpr();
+            auto op = op1->GetType()->Tag() == TYPE_TABLE ? OP_TABLE_HAS_ELEMENTS_VV : OP_VECTOR_HAS_ELEMENTS_VV;
+            return AddInst(GenInst(op, lhs, n));
+        }
+
+        case ScriptOptBuiltinExpr::FUNC_ID_STRING: {
+            auto n = op1->AsNameExpr();
+            return AddInst(GenInst(OP_FUNC_ID_STRING_VV, lhs, n));
+        }
+
+        default: reporter->InternalError("bad built-in tag in ZAMCompiler::CompileZAMBuiltin");
+    }
+}
+
 const ZAMStmt ZAMCompiler::CompileAssignToIndex(const NameExpr* lhs, const IndexExpr* rhs) {
     auto aggr = rhs->GetOp1();
     auto const_aggr = aggr->Tag() == EXPR_CONST;

src/script_opt/ZAM/Ops.in

@@ -666,6 +666,38 @@ type VVV
 eval	if ( frame[z.v1].record_val->HasField(z.v2) )
 		BRANCH(v3)
 
+internal-op Table-Has-Elements
+type VV
+eval	frame[z.v1].int_val = frame[z.v2].table_val->Size() > 0;
+
+internal-op Table-Has-Elements-Cond
+op1-read
+type VV
+eval	if ( frame[z.v1].table_val->Size() == 0 )
+		BRANCH(v2)
+
+internal-op Not-Table-Has-Elements-Cond
+op1-read
+type VV
+eval	if ( frame[z.v1].table_val->Size() > 0 )
+		BRANCH(v2)
+
+internal-op Vector-Has-Elements
+type VV
+eval	frame[z.v1].int_val = frame[z.v2].vector_val->Size() > 0;
+
+internal-op Vector-Has-Elements-Cond
+op1-read
+type VV
+eval	if ( frame[z.v1].vector_val->Size() == 0 )
+		BRANCH(v2)
+
+internal-op Not-Vector-Has-Elements-Cond
+op1-read
+type VV
+eval	if ( frame[z.v1].vector_val->Size() > 0 )
+		BRANCH(v2)
+
 expr-op In
 type VVV
 custom-method return CompileInExpr(n1, n2, n3);