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 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'chapter07/src/main') diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/SubNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/SubNode.java index 650b7856..421e659b 100644 --- a/chapter07/src/main/java/com/seaofnodes/simple/node/SubNode.java +++ b/chapter07/src/main/java/com/seaofnodes/simple/node/SubNode.java @@ -39,11 +39,11 @@ 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 ) -- cgit v1.2.3