diff options
Diffstat (limited to 'chapter04')
| -rw-r--r-- | chapter04/README.md | 4 | ||||
| -rw-r--r-- | chapter04/src/main/java/com/seaofnodes/simple/node/SubNode.java | 19 | ||||
| -rw-r--r-- | chapter04/src/test/java/com/seaofnodes/simple/Chapter04Test.java | 28 |
3 files changed, 51 insertions, 0 deletions
diff --git a/chapter04/README.md b/chapter04/README.md index 2c7f7e9c..07085e80 100644 --- a/chapter04/README.md +++ b/chapter04/README.md @@ -305,6 +305,7 @@ Here is a list of peepholes introduced in this Chapter, more will be introduced | Before | After | Description | |-----------------------|-----------------------|------------------------------------------------| | (arg + 0 ) | arg | Add of zero identity | +| (arg - 0 ) | arg | Sub of zero identity | | (arg * 1 ) | arg | Multiple of one identity | | (con + arg) | (arg + con) | Move constants to right, to encourage folding | | (con * arg) | (arg * con) | Move constants to right, to encourage folding | @@ -312,6 +313,9 @@ Here is a list of peepholes introduced in this Chapter, more will be introduced | ((arg1 + con) + arg2) | ((arg1 + arg2) + con) | Move constants to right, to encourage folding | | (arg + arg) | (arg * 2) | Sum-of-products form | | (arg - arg) | 0 | Sub of same is 0 +| (0 - arg) | (-arg) | Sub from 0 is negation +| (arg1 - (-arg2)) | (arg1 + arg2) | Sub of negation is add +| ((-arg1) - arg2) | -(arg1 + arg2) | Sub from negation is negation of sum | (con / 1) | con | Division by one | (arg == arg) | 1 | Compare of same | (arg != arg) | 0 | Compare of same diff --git a/chapter04/src/main/java/com/seaofnodes/simple/node/SubNode.java b/chapter04/src/main/java/com/seaofnodes/simple/node/SubNode.java index f5ad663d..c831a798 100644 --- a/chapter04/src/main/java/com/seaofnodes/simple/node/SubNode.java +++ b/chapter04/src/main/java/com/seaofnodes/simple/node/SubNode.java @@ -32,6 +32,25 @@ public class SubNode extends Node { @Override public Node idealize() { + Node lhs = in(1); + Node rhs = in(2); + Type t1 = lhs._type; + Type t2 = rhs._type; + + // Keep invalid operands for type checking. + if( t1 instanceof TypeInteger x && t2 instanceof TypeInteger y ) { + if( y.isConstant() && y.value()==0 ) return lhs; + if( x.isConstant() && x.value()==0 ) return new MinusNode(rhs); + } + + // x - (-y) is x+y + if( rhs instanceof MinusNode minus ) + return new AddNode(lhs,minus.in(1)); + + // (-x) - y is -(x+y) + if( lhs instanceof MinusNode minus ) + return new MinusNode(new AddNode(minus.in(1),rhs).peephole()); + return null; } diff --git a/chapter04/src/test/java/com/seaofnodes/simple/Chapter04Test.java b/chapter04/src/test/java/com/seaofnodes/simple/Chapter04Test.java index 28912d5d..74682310 100644 --- a/chapter04/src/test/java/com/seaofnodes/simple/Chapter04Test.java +++ b/chapter04/src/test/java/com/seaofnodes/simple/Chapter04Test.java @@ -51,6 +51,34 @@ public class Chapter04Test { } @Test + public void testSub0() { + Parser parser = new Parser("return arg-0;"); + ReturnNode ret = parser.parse(); + assertEquals("return arg;", ret.print()); + } + + @Test + public void test0Sub() { + Parser parser = new Parser("return 0-arg;"); + ReturnNode ret = parser.parse(); + assertEquals("return (-arg);", ret.print()); + } + + @Test + public void testSubNeg() { + Parser parser = new Parser("return 3--arg;"); + ReturnNode ret = parser.parse(); + assertEquals("return (arg+3);", ret.print()); + } + + @Test + public void testNegSub() { + Parser parser = new Parser("return -arg-3;"); + ReturnNode ret = parser.parse(); + assertEquals("return (-(arg+3));", ret.print()); + } + + @Test public void testVarArg() { Parser parser = new Parser("return arg; ", TypeInteger.BOT); ReturnNode ret = parser.parse(); |