From f70c77e1c4d5b6c951669d79cf73a1ff0b932312 Mon Sep 17 00:00:00 2001 From: Lukas Rytz Date: Fri, 12 Feb 2016 14:04:44 +0100 Subject: Generate leaner code for branches GenBCode used to generate more bytecode for branching instructions than GenASM. A simple method def f(x: Int, b: Boolean) = if (b) 1 else 2 would generate ILOAD 2 IFNE L1 GOTO L2 L1 ICONST_1 GOTO L3 L2 ICONST_2 L3 IRETURN If the conditional branch is negated (IFEQ) the GOTO is unnecessary. While -Yopt:l:method would clean this up, it's also not too hard to generate the leaner bytecode in the first place. --- .../tools/nsc/backend/jvm/BCodeBodyBuilder.scala | 172 ++++++++++----------- .../scala/tools/nsc/backend/jvm/BCodeHelpers.scala | 9 ++ 2 files changed, 94 insertions(+), 87 deletions(-) (limited to 'src/compiler/scala') diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BCodeBodyBuilder.scala b/src/compiler/scala/tools/nsc/backend/jvm/BCodeBodyBuilder.scala index a28d4b0083..1e7ea0c09d 100644 --- a/src/compiler/scala/tools/nsc/backend/jvm/BCodeBodyBuilder.scala +++ b/src/compiler/scala/tools/nsc/backend/jvm/BCodeBodyBuilder.scala @@ -202,14 +202,14 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { val hasElse = !elsep.isEmpty val postIf = if (hasElse) new asm.Label else failure - genCond(condp, success, failure) + genCond(condp, success, failure, targetIfNoJump = success) + markProgramPoint(success) val thenKind = tpeTK(thenp) val elseKind = if (!hasElse) UNIT else tpeTK(elsep) def hasUnitBranch = (thenKind == UNIT || elseKind == UNIT) val resKind = if (hasUnitBranch) UNIT else tpeTK(tree) - markProgramPoint(success) genLoad(thenp, resKind) if (hasElse) { bc goTo postIf } markProgramPoint(failure) @@ -234,14 +234,14 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { else if (isArrayOp(code)) genArrayOp(tree, code, expectedType) else if (isLogicalOp(code) || isComparisonOp(code)) { val success, failure, after = new asm.Label - genCond(tree, success, failure) + genCond(tree, success, failure, targetIfNoJump = success) // success block - markProgramPoint(success) - bc boolconst true - bc goTo after + markProgramPoint(success) + bc boolconst true + bc goTo after // failure block - markProgramPoint(failure) - bc boolconst false + markProgramPoint(failure) + bc boolconst false // after markProgramPoint(after) @@ -1108,53 +1108,58 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { } /* Emit code to compare the two top-most stack values using the 'op' operator. */ - private def genCJUMP(success: asm.Label, failure: asm.Label, op: TestOp, tk: BType) { - if (tk.isIntSizedType) { // BOOL, BYTE, CHAR, SHORT, or INT - bc.emitIF_ICMP(op, success) - } else if (tk.isRef) { // REFERENCE(_) | ARRAY(_) - bc.emitIF_ACMP(op, success) - } else { - (tk: @unchecked) match { - case LONG => emit(asm.Opcodes.LCMP) - case FLOAT => - if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.FCMPG) - else emit(asm.Opcodes.FCMPL) - case DOUBLE => - if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.DCMPG) - else emit(asm.Opcodes.DCMPL) + private def genCJUMP(success: asm.Label, failure: asm.Label, op: TestOp, tk: BType, targetIfNoJump: asm.Label) { + if (targetIfNoJump == success) genCJUMP(failure, success, op.negate, tk, targetIfNoJump) + else { + if (tk.isIntSizedType) { // BOOL, BYTE, CHAR, SHORT, or INT + bc.emitIF_ICMP(op, success) + } else if (tk.isRef) { // REFERENCE(_) | ARRAY(_) + bc.emitIF_ACMP(op, success) + } else { + (tk: @unchecked) match { + case LONG => emit(asm.Opcodes.LCMP) + case FLOAT => + if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.FCMPG) + else emit(asm.Opcodes.FCMPL) + case DOUBLE => + if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.DCMPG) + else emit(asm.Opcodes.DCMPL) + } + bc.emitIF(op, success) } - bc.emitIF(op, success) + if (targetIfNoJump != failure) bc goTo failure } - bc goTo failure } /* Emits code to compare (and consume) stack-top and zero using the 'op' operator */ - private def genCZJUMP(success: asm.Label, failure: asm.Label, op: TestOp, tk: BType) { - if (tk.isIntSizedType) { // BOOL, BYTE, CHAR, SHORT, or INT - bc.emitIF(op, success) - } else if (tk.isRef) { // REFERENCE(_) | ARRAY(_) - // @unchecked because references aren't compared with GT, GE, LT, LE. - (op : @unchecked) match { - case TestOp.EQ => bc emitIFNULL success - case TestOp.NE => bc emitIFNONNULL success - } - } else { - (tk: @unchecked) match { - case LONG => - emit(asm.Opcodes.LCONST_0) - emit(asm.Opcodes.LCMP) - case FLOAT => - emit(asm.Opcodes.FCONST_0) - if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.FCMPG) - else emit(asm.Opcodes.FCMPL) - case DOUBLE => - emit(asm.Opcodes.DCONST_0) - if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.DCMPG) - else emit(asm.Opcodes.DCMPL) + private def genCZJUMP(success: asm.Label, failure: asm.Label, op: TestOp, tk: BType, targetIfNoJump: asm.Label) { + if (targetIfNoJump == success) genCZJUMP(failure, success, op.negate, tk, targetIfNoJump) + else { + if (tk.isIntSizedType) { // BOOL, BYTE, CHAR, SHORT, or INT + bc.emitIF(op, success) + } else if (tk.isRef) { // REFERENCE(_) | ARRAY(_) + op match { // references are only compared with EQ and NE + case TestOp.EQ => bc emitIFNULL success + case TestOp.NE => bc emitIFNONNULL success + } + } else { + (tk: @unchecked) match { + case LONG => + emit(asm.Opcodes.LCONST_0) + emit(asm.Opcodes.LCMP) + case FLOAT => + emit(asm.Opcodes.FCONST_0) + if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.FCMPG) + else emit(asm.Opcodes.FCMPL) + case DOUBLE => + emit(asm.Opcodes.DCONST_0) + if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.DCMPG) + else emit(asm.Opcodes.DCMPL) + } + bc.emitIF(op, success) } - bc.emitIF(op, success) + if (targetIfNoJump != failure) bc goTo failure } - bc goTo failure } def testOpForPrimitive(primitiveCode: Int) = (primitiveCode: @switch) match { @@ -1179,29 +1184,26 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { * Generate code for conditional expressions. * The jump targets success/failure of the test are `then-target` and `else-target` resp. */ - private def genCond(tree: Tree, success: asm.Label, failure: asm.Label) { + private def genCond(tree: Tree, success: asm.Label, failure: asm.Label, targetIfNoJump: asm.Label) { def genComparisonOp(l: Tree, r: Tree, code: Int) { - val op: TestOp = testOpForPrimitive(code) - // special-case reference (in)equality test for null (null eq x, x eq null) - var nonNullSide: Tree = null - if (scalaPrimitives.isReferenceEqualityOp(code) && - { nonNullSide = ifOneIsNull(l, r); nonNullSide != null } - ) { + val op = testOpForPrimitive(code) + val nonNullSide = if (scalaPrimitives.isReferenceEqualityOp(code)) ifOneIsNull(l, r) else null + if (nonNullSide != null) { + // special-case reference (in)equality test for null (null eq x, x eq null) genLoad(nonNullSide, ObjectRef) - genCZJUMP(success, failure, op, ObjectRef) - } - else { + genCZJUMP(success, failure, op, ObjectRef, targetIfNoJump) + } else { val tk = tpeTK(l).maxType(tpeTK(r)) genLoad(l, tk) genLoad(r, tk) - genCJUMP(success, failure, op, tk) + genCJUMP(success, failure, op, tk, targetIfNoJump) } } - def default() = { + def loadAndTestBoolean() = { genLoad(tree, BOOL) - genCZJUMP(success, failure, TestOp.NE, BOOL) + genCZJUMP(success, failure, TestOp.NE, BOOL, targetIfNoJump) } lineNumber(tree) @@ -1212,37 +1214,35 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { // lhs and rhs of test lazy val Select(lhs, _) = fun - val rhs = if (args.isEmpty) EmptyTree else args.head; // args.isEmpty only for ZNOT + val rhs = if (args.isEmpty) EmptyTree else args.head // args.isEmpty only for ZNOT - def genZandOrZor(and: Boolean) { // TODO WRONG + def genZandOrZor(and: Boolean) { // reaching "keepGoing" indicates the rhs should be evaluated too (ie not short-circuited). val keepGoing = new asm.Label - if (and) genCond(lhs, keepGoing, failure) - else genCond(lhs, success, keepGoing) + if (and) genCond(lhs, keepGoing, failure, targetIfNoJump = keepGoing) + else genCond(lhs, success, keepGoing, targetIfNoJump = keepGoing) markProgramPoint(keepGoing) - genCond(rhs, success, failure) + genCond(rhs, success, failure, targetIfNoJump) } getPrimitive(fun.symbol) match { - case ZNOT => genCond(lhs, failure, success) + case ZNOT => genCond(lhs, failure, success, targetIfNoJump) case ZAND => genZandOrZor(and = true) case ZOR => genZandOrZor(and = false) case code => - // TODO !!!!!!!!!! isReferenceType, in the sense of TypeKind? (ie non-array, non-boxed, non-nothing, may be null) if (scalaPrimitives.isUniversalEqualityOp(code) && tpeTK(lhs).isClass) { - // `lhs` has reference type - if (code == EQ) genEqEqPrimitive(lhs, rhs, success, failure, tree.pos) - else genEqEqPrimitive(lhs, rhs, failure, success, tree.pos) - } - else if (scalaPrimitives.isComparisonOp(code)) + // rewrite `==` to null tests and `equals`. not needed for arrays (`equals` is reference equality). + if (code == EQ) genEqEqPrimitive(lhs, rhs, success, failure, targetIfNoJump, tree.pos) + else genEqEqPrimitive(lhs, rhs, failure, success, targetIfNoJump, tree.pos) + } else if (scalaPrimitives.isComparisonOp(code)) { genComparisonOp(lhs, rhs, code) - else - default + } else + loadAndTestBoolean() } - case _ => default + case _ => loadAndTestBoolean() } } // end of genCond() @@ -1254,7 +1254,7 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { * @param l left-hand-side of the '==' * @param r right-hand-side of the '==' */ - def genEqEqPrimitive(l: Tree, r: Tree, success: asm.Label, failure: asm.Label, pos: Position) { + def genEqEqPrimitive(l: Tree, r: Tree, success: asm.Label, failure: asm.Label, targetIfNoJump: asm.Label, pos: Position) { /* True if the equality comparison is between values that require the use of the rich equality * comparator (scala.runtime.Comparator.equals). This is the case when either side of the @@ -1264,7 +1264,6 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { */ val mustUseAnyComparator: Boolean = { val areSameFinals = l.tpe.isFinalType && r.tpe.isFinalType && (l.tpe =:= r.tpe) - !areSameFinals && platform.isMaybeBoxed(l.tpe.typeSymbol) && platform.isMaybeBoxed(r.tpe.typeSymbol) } @@ -1279,23 +1278,22 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { genLoad(l, ObjectRef) genLoad(r, ObjectRef) genCallMethod(equalsMethod, InvokeStyle.Static, pos) - genCZJUMP(success, failure, TestOp.NE, BOOL) - } - else { + genCZJUMP(success, failure, TestOp.NE, BOOL, targetIfNoJump) + } else { if (isNull(l)) { // null == expr -> expr eq null genLoad(r, ObjectRef) - genCZJUMP(success, failure, TestOp.EQ, ObjectRef) + genCZJUMP(success, failure, TestOp.EQ, ObjectRef, targetIfNoJump) } else if (isNull(r)) { // expr == null -> expr eq null genLoad(l, ObjectRef) - genCZJUMP(success, failure, TestOp.EQ, ObjectRef) + genCZJUMP(success, failure, TestOp.EQ, ObjectRef, targetIfNoJump) } else if (isNonNullExpr(l)) { // SI-7852 Avoid null check if L is statically non-null. genLoad(l, ObjectRef) genLoad(r, ObjectRef) genCallMethod(Object_equals, InvokeStyle.Virtual, pos) - genCZJUMP(success, failure, TestOp.NE, BOOL) + genCZJUMP(success, failure, TestOp.NE, BOOL, targetIfNoJump) } else { // l == r -> if (l eq null) r eq null else l.equals(r) val eqEqTempLocal = locals.makeLocal(ObjectRef, nme.EQEQ_LOCAL_VAR.toString) @@ -1306,17 +1304,17 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { genLoad(r, ObjectRef) locals.store(eqEqTempLocal) bc dup ObjectRef - genCZJUMP(lNull, lNonNull, TestOp.EQ, ObjectRef) + genCZJUMP(lNull, lNonNull, TestOp.EQ, ObjectRef, targetIfNoJump = lNull) markProgramPoint(lNull) bc drop ObjectRef locals.load(eqEqTempLocal) - genCZJUMP(success, failure, TestOp.EQ, ObjectRef) + genCZJUMP(success, failure, TestOp.EQ, ObjectRef, targetIfNoJump = lNonNull) markProgramPoint(lNonNull) locals.load(eqEqTempLocal) genCallMethod(Object_equals, InvokeStyle.Virtual, pos) - genCZJUMP(success, failure, TestOp.NE, BOOL) + genCZJUMP(success, failure, TestOp.NE, BOOL, targetIfNoJump) } } } diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala b/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala index 1b5ece772c..f423f3c7fe 100644 --- a/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala +++ b/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala @@ -1355,6 +1355,15 @@ object BCodeHelpers { } class TestOp(val op: Int) extends AnyVal { + import TestOp._ + def negate = this match { + case EQ => NE + case NE => EQ + case LT => GE + case GE => LT + case GT => LE + case LE => GT + } def opcodeIF = asm.Opcodes.IFEQ + op def opcodeIFICMP = asm.Opcodes.IF_ICMPEQ + op } -- cgit v1.2.3