From 6e59fc1b71f2098c8baf90a6c54e5a33b7291e94 Mon Sep 17 00:00:00 2001 From: Cliff Click Date: Sat, 19 Sep 2026 22:31:42 -0700 Subject: Unify mixed-return checking and results Unify dominator caching. --- .../com/seaofnodes/simple/codegen/CodeGen.java | 24 +++++++--------------- .../simple/codegen/GlobalCodeMotion.java | 6 +++--- .../java/com/seaofnodes/simple/node/CFGNode.java | 20 +++++++++++++----- .../java/com/seaofnodes/simple/node/FunNode.java | 4 +--- .../java/com/seaofnodes/simple/node/LoadNode.java | 2 +- .../java/com/seaofnodes/simple/node/LoopNode.java | 4 +--- .../com/seaofnodes/simple/node/RegionNode.java | 14 ++++++------- .../com/seaofnodes/simple/node/ReturnNode.java | 6 ++---- .../java/com/seaofnodes/simple/node/StartNode.java | 2 +- .../java/com/seaofnodes/simple/node/StopNode.java | 4 ++-- 10 files changed, 39 insertions(+), 47 deletions(-) (limited to 'chapter22/src/main/java/com/seaofnodes') diff --git a/chapter22/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java b/chapter22/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java index adb71413..1726695f 100644 --- a/chapter22/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java +++ b/chapter22/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java @@ -89,22 +89,12 @@ public class CodeGen { public int getALIAS() { return _alias++; } - // idepths are cached and valid until *inserting* CFG edges (deleting is - // OK). This happens with inlining, which bumps the version to bulk - // invalidate the idepth caches. - private int _iDepthVersion = 0; - public void invalidateIDepthCaches() { _iDepthVersion++; } - public boolean validIDepth(int idepth) { - if( idepth==0 ) return false; - if( _iDepthVersion==0 ) return true; - return (idepth%100)==_iDepthVersion; - } - public int iDepthAt(int idepth) { - return 100*idepth+_iDepthVersion; - } - public int iDepthFrom(int idepth) { - assert idepth==0 || validIDepth(idepth); - return idepth+100; + // Inlining can insert CFG edges and invalidate cached depth ordering. + private char _iDepthVersion; + public char iDepthVersion() { return _iDepthVersion; } + public void invalidateIDepthCaches() { + assert _iDepthVersion < Character.MAX_VALUE : "Dominator cache version exceeds 65535"; + ++_iDepthVersion; } // Popular visit bitset, declared here, so it gets reused all over @@ -462,7 +452,7 @@ public class CodeGen { if( _cfg==null ) return "no CFG"; SB sb = new SB(); for( CFGNode cfg : _cfg ) { - sb.fix(8,""+cfg._idepth); + sb.fix(8,""+(int)cfg._idepth); IRPrinter.printLine( cfg, sb ); } return sb.toString(); diff --git a/chapter22/src/main/java/com/seaofnodes/simple/codegen/GlobalCodeMotion.java b/chapter22/src/main/java/com/seaofnodes/simple/codegen/GlobalCodeMotion.java index 04a119c2..1542c04d 100644 --- a/chapter22/src/main/java/com/seaofnodes/simple/codegen/GlobalCodeMotion.java +++ b/chapter22/src/main/java/com/seaofnodes/simple/codegen/GlobalCodeMotion.java @@ -203,7 +203,7 @@ public abstract class GlobalCodeMotion { CFGNode lca = null; for( Node use : n._outputs ) if( use != null ) - lca = use_block(n,use, late)._idom(lca,null); + lca = use_block(n,use, late).domLCA(lca,null); // Loads may need anti-dependencies, raising their LCA if( n instanceof MemOpNode load && load._isLoad ) @@ -257,7 +257,7 @@ public abstract class GlobalCodeMotion { CFGNode found=null; for( int i=1; i * See {@link ...} */ - public int _idepth; - public int idepth() { - return CodeGen.CODE.validIDepth(_idepth) ? _idepth : (_idepth=CodeGen.CODE.iDepthFrom(idom().idepth())); + public char _idepth; + public char _idepthVersion; + public int idepth() { return validIDepth() ? _idepth : cacheIDepth(idom().idepth()+1); } + // Zero depth means uncached. Check before narrowing so overflow cannot wrap. + final int cacheIDepth(int depth) { + assert 0 <= depth && depth <= Character.MAX_VALUE : "Dominator depth exceeds 65535"; + _idepthVersion = CodeGen.CODE.iDepthVersion(); + return _idepth = (char)depth; } + final boolean validIDepth() { return _idepth!=0 && _idepthVersion==CodeGen.CODE.iDepthVersion(); } + + // Return the immediate dominator of this Node and compute dom tree depth. public CFGNode idom(Node dep) { return cfg(0); } public final CFGNode idom() { return idom(null); } // Return the LCA of two idoms - public CFGNode _idom(CFGNode rhs, Node dep) { + public CFGNode domLCA(CFGNode rhs, Node dep) { if( rhs==null ) return this; CFGNode lhs = this; while( lhs != rhs ) { - var comp = lhs.idepth() - rhs.idepth(); + if( lhs==null || rhs==null ) return null; + int comp = lhs.idepth() - rhs.idepth(); if( comp >= 0 ) lhs = (dep==null ? lhs : dep.addDep(lhs)).idom(); if( comp <= 0 ) rhs = (dep==null ? rhs : dep.addDep(rhs)).idom(); } diff --git a/chapter22/src/main/java/com/seaofnodes/simple/node/FunNode.java b/chapter22/src/main/java/com/seaofnodes/simple/node/FunNode.java index 81fa627a..c53807a6 100644 --- a/chapter22/src/main/java/com/seaofnodes/simple/node/FunNode.java +++ b/chapter22/src/main/java/com/seaofnodes/simple/node/FunNode.java @@ -121,9 +121,7 @@ public class FunNode extends RegionNode { // Bypass Region idom, always assume depth == 1, one more than Start, // unless folding then just a ID on input#1 - @Override public int idepth() { - return _folding ? super.idepth() : CodeGen.CODE.iDepthAt(1); - } + @Override public int idepth() { return _folding ? super.idepth() : 1; } // Bypass Region idom, always assume idom is Start @Override public CFGNode idom(Node dep) { return _folding && nIns()==3 ? cfg(2) : cfg(1); } diff --git a/chapter22/src/main/java/com/seaofnodes/simple/node/LoadNode.java b/chapter22/src/main/java/com/seaofnodes/simple/node/LoadNode.java index eebe94a3..10de5e53 100644 --- a/chapter22/src/main/java/com/seaofnodes/simple/node/LoadNode.java +++ b/chapter22/src/main/java/com/seaofnodes/simple/node/LoadNode.java @@ -71,7 +71,7 @@ public class LoadNode extends MemOpNode { for( Node memuse : mem._outputs ) // Find a prior load, has same mem,ptr,off but higher ctrl if( memuse != this && memuse instanceof LoadNode ld && ptr==ld.ptr() && off()==ld.off() && - cfg0()!=null && cfg0()._idom(ld.cfg0(),this) == ld.cfg0() ) // Higher control means load is legal earlier + cfg0()!=null && cfg0().domLCA(ld.cfg0(),this) == ld.cfg0() ) // Higher control means load is legal earlier return ld; // Load-after-Store on same address, but bypassing provably unrelated diff --git a/chapter22/src/main/java/com/seaofnodes/simple/node/LoopNode.java b/chapter22/src/main/java/com/seaofnodes/simple/node/LoopNode.java index ec9055dc..334ac686 100644 --- a/chapter22/src/main/java/com/seaofnodes/simple/node/LoopNode.java +++ b/chapter22/src/main/java/com/seaofnodes/simple/node/LoopNode.java @@ -26,9 +26,7 @@ public class LoopNode extends RegionNode { } // Bypass Region idom, same as the default idom() using use in(1) instead of in(0) - @Override public int idepth() { - return CodeGen.CODE.validIDepth(_idepth) ? _idepth : (_idepth=CodeGen.CODE.iDepthFrom(idom().idepth())); - } + @Override public int idepth() { return validIDepth() ? _idepth : cacheIDepth(entry().idepth()+1); } // Bypass Region idom, same as the default idom() using use in(1) instead of in(0) @Override public CFGNode idom(Node dep) { return entry(); } diff --git a/chapter22/src/main/java/com/seaofnodes/simple/node/RegionNode.java b/chapter22/src/main/java/com/seaofnodes/simple/node/RegionNode.java index 8f65d0e5..64747c63 100644 --- a/chapter22/src/main/java/com/seaofnodes/simple/node/RegionNode.java +++ b/chapter22/src/main/java/com/seaofnodes/simple/node/RegionNode.java @@ -141,21 +141,19 @@ public class RegionNode extends CFGNode { // Immediate dominator of Region is a little more complicated. @Override public int idepth() { - if( CodeGen.CODE.validIDepth(_idepth) ) - return _idepth; - int d=0; + if( validIDepth() ) return _idepth; + int depth=0; for( Node n : _inputs ) if( n!=null ) - d = Math.max(d,CodeGen.CODE.iDepthFrom(((CFGNode)n).idepth())); - return _idepth = d; + depth = Math.max(depth,((CFGNode)n).idepth()+1); + return cacheIDepth(depth); } @Override public CFGNode idom(Node dep) { CFGNode lca = null; - // Walk the LHS & RHS idom trees in parallel until they match, or either fails. - // Because this does not cache, it can be linear in the size of the program. + // Recompute from predecessors: CFG edits can change the dominator. for( int i=1; i