From 29e0127170dce8964d7f85d808d1ec07426d2789 Mon Sep 17 00:00:00 2001 From: Cliff Click Date: Fri, 25 Sep 2026 15:28:21 -0700 Subject: Restrict subtraction zero peepholes to integer operands Require resolved integer mode in chapter 25 so zero subtraction preserves floating-point signed zero. Keep nonnumeric operands in the graph for subtraction diagnostics. Add signed-zero coverage from chapter 12 and null-subtraction diagnostics from chapter 22. Confirmed the regressions fail on the original PR. Full Make suites pass in chapters 4-25 (5462 tests), including fresh chapter 25 sys.o compilation. --- .../src/main/java/com/seaofnodes/simple/node/SubNode.java | 10 +++++----- .../src/test/java/com/seaofnodes/simple/Chapter12Test.java | 7 +++++++ 2 files changed, 12 insertions(+), 5 deletions(-) (limited to 'chapter13') diff --git a/chapter13/src/main/java/com/seaofnodes/simple/node/SubNode.java b/chapter13/src/main/java/com/seaofnodes/simple/node/SubNode.java index d55cbb4e..4ae302f0 100644 --- a/chapter13/src/main/java/com/seaofnodes/simple/node/SubNode.java +++ b/chapter13/src/main/java/com/seaofnodes/simple/node/SubNode.java @@ -44,11 +44,11 @@ public class SubNode extends Node { Type t1 = lhs._type; Type t2 = rhs._type; - if( t2.isConstant() && t2 instanceof TypeInteger i && i.value()==0 ) - return lhs; - - if( t1.isConstant() && t1 instanceof TypeInteger i && i.value()==0 ) - return new MinusNode(rhs); + // 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 ) diff --git a/chapter13/src/test/java/com/seaofnodes/simple/Chapter12Test.java b/chapter13/src/test/java/com/seaofnodes/simple/Chapter12Test.java index 57455510..a1c7a92a 100644 --- a/chapter13/src/test/java/com/seaofnodes/simple/Chapter12Test.java +++ b/chapter13/src/test/java/com/seaofnodes/simple/Chapter12Test.java @@ -8,6 +8,13 @@ import static org.junit.Assert.assertEquals; import static org.junit.Assert.fail; public class Chapter12Test { + @Test public void testSubZeroFloat() { + var stop = new Parser("flt x = arg; return 0-x;").parse().iterate(); + // Compare strings so +0.0 and -0.0 remain distinct. + assertEquals("0.0", Evaluator.evaluate(stop,0).toString()); + assertEquals("-1.0", Evaluator.evaluate(stop,1).toString()); + } + @Test public void testDeadNumericReturns() { for( String[] test : new String[][] { {"if(1) return 7; else return 2.5;", "7"}, -- cgit v1.2.3