diff options
Diffstat (limited to 'chapter24/src')
9 files changed, 125 insertions, 13 deletions
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/codegen/BuildLRG.java b/chapter24/src/main/java/com/seaofnodes/simple/codegen/BuildLRG.java index f4ce4366..2319714b 100644 --- a/chapter24/src/main/java/com/seaofnodes/simple/codegen/BuildLRG.java +++ b/chapter24/src/main/java/com/seaofnodes/simple/codegen/BuildLRG.java @@ -1,6 +1,7 @@ package com.seaofnodes.simple.codegen; import com.seaofnodes.simple.node.*; +import com.seaofnodes.simple.type.Type; import com.seaofnodes.simple.type.TypeMem; abstract public class BuildLRG { @@ -16,8 +17,10 @@ abstract public class BuildLRG { public static boolean run(int round, RegAlloc alloc) { for( Node bb : alloc._code._cfg ) for( Node n : bb.outs() ) { + // A synthetic never-exit value has no runtime definition. + if( n._type==Type.TOP ) continue; if( n instanceof PhiNode phi && !(phi._type instanceof TypeMem) ) { - // All Phi inputs end up with the same LRG. + // All real Phi inputs end up with the same LRG. // Pass 1: find any pre-existing LRG, to avoid make-then-Union a LRG LRG lrg = alloc.lrg(phi); if( lrg == null ) @@ -30,7 +33,9 @@ abstract public class BuildLRG { // Pass 2: everybody uses the same LRG lrg=alloc.union(lrg,phi); for( int i=phi instanceof ParmNode ? 2 : 1; i<n.nIns(); i++ ) - lrg=alloc.union(lrg,n.in(i)); + // TOP keeps the type merge neutral, but needs no register. + if( n.in(i)._type!=Type.TOP ) + lrg=alloc.union(lrg,n.in(i)); if( lrg._mask!=null && lrg._mask.isEmpty() ) alloc.fail(lrg); diff --git a/chapter24/src/main/java/com/seaofnodes/simple/codegen/IFG.java b/chapter24/src/main/java/com/seaofnodes/simple/codegen/IFG.java index ecff9aac..bcd1957d 100644 --- a/chapter24/src/main/java/com/seaofnodes/simple/codegen/IFG.java +++ b/chapter24/src/main/java/com/seaofnodes/simple/codegen/IFG.java @@ -1,6 +1,7 @@ package com.seaofnodes.simple.codegen; import com.seaofnodes.simple.node.*; +import com.seaofnodes.simple.type.Type; import com.seaofnodes.simple.util.Ary; import com.seaofnodes.simple.util.Utils; import java.util.BitSet; @@ -241,6 +242,8 @@ abstract public class IFG { assert i!=0; def = phi.in( i ); } + // The synthetic exit carries no value on this Phi arm. + if( def._type==Type.TOP ) continue; Node def_bb = lrgs.get(lrg); if( def_bb==null ) { lrgs.put(lrg,def); diff --git a/chapter24/src/main/java/com/seaofnodes/simple/codegen/RegAlloc.java b/chapter24/src/main/java/com/seaofnodes/simple/codegen/RegAlloc.java index b2b861e2..0899099e 100644 --- a/chapter24/src/main/java/com/seaofnodes/simple/codegen/RegAlloc.java +++ b/chapter24/src/main/java/com/seaofnodes/simple/codegen/RegAlloc.java @@ -3,6 +3,7 @@ package com.seaofnodes.simple.codegen; import com.seaofnodes.simple.util.Ary; import com.seaofnodes.simple.util.Utils; import com.seaofnodes.simple.node.*; +import com.seaofnodes.simple.type.Type; import java.util.Arrays; import java.util.BitSet; import java.util.IdentityHashMap; @@ -418,7 +419,8 @@ public class RegAlloc { // PhiNodes check all CFG inputs if( n instanceof PhiNode phi ) { for( int i=1; i<n.nIns(); i++ ) - ld = ldepth(ld, phi.in(i), phi.region().cfg(i)); + if( phi.in(i)._type!=Type.TOP ) + ld = ldepth(ld, phi.in(i), phi.region().cfg(i)); } else { // Others check uses for( int i=1; i<n.nIns(); i++ ) @@ -535,6 +537,8 @@ public class RegAlloc { void insertBefore(Node n, int i, String kind, byte round, LRG lrg, boolean skip) { Node def = n.in(i); + // Phi splitting may visit the synthetic never-exit arm. + if( def._type==Type.TOP ) return; // Effective block for use CFGNode cfg = n instanceof PhiNode phi ? phi.region().cfg(i) : n.cfg0(); // Use-side RegMask, if available diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/CFGNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/CFGNode.java index 420c8117..6805c1ef 100644 --- a/chapter24/src/main/java/com/seaofnodes/simple/node/CFGNode.java +++ b/chapter24/src/main/java/com/seaofnodes/simple/node/CFGNode.java @@ -132,7 +132,7 @@ public abstract class CFGNode extends Node { // ------------------------------------------------------------------------ // Tag all CFG Nodes with their containing LoopNode; LoopNodes themselves // also refer to *their* containing LoopNode, as well as have their depth. - // Start is a LoopNode which contains all at depth 1. + // Start contains the function bodies at depth 0; real loops add depth. public void buildLoopTree(StartNode start, StopNode stop) { // Unlink all linked calls. This can remove RPC constants which // shuffled the StartNode outputs so requires a while loop. @@ -153,6 +153,14 @@ public abstract class CFGNode extends Node { // Pre-walked? if( _pre!=0 ) return pre; _pre = pre++; + // Seed the function's outer tree before walking its body. Synthetic + // exits can be added before the post-order walk reaches the entry. + if( this instanceof FunNode ) _ltree = stop._ltree; + if( this instanceof ReturnNode ) { + _ltree = fun._ltree; + post.set(_nid); + return pre; // Stop/Start links describe the outside world, not a loop. + } // Pre-walk for( Node use : _outputs ) if( use instanceof CFGNode usecfg && !skip( usecfg ) ) diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/LoopNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/LoopNode.java index db52c156..1d493db7 100644 --- a/chapter24/src/main/java/com/seaofnodes/simple/node/LoopNode.java +++ b/chapter24/src/main/java/com/seaofnodes/simple/node/LoopNode.java @@ -32,7 +32,7 @@ public class LoopNode extends RegionNode { // If this is an unreachable loop, it may not have an exit. If it does not // (i.e., infinite loop), force an exit to make it reachable. - public StopNode forceExit( FunNode fun, StopNode stop ) { + public FunNode forceExit( FunNode fun, StopNode stop ) { // Walk the backedge, then immediate dominator tree util we hit this // Loop again. If we ever hit a CProj from an If (as opposed to // directly on the If) we found our exit. @@ -41,7 +41,7 @@ public class LoopNode extends RegionNode { if( x instanceof CProjNode exit && exit.in(0) instanceof IfNode iff ) { CFGNode other = iff.cproj(1-exit._idx); if( other!=null && other._ltree != _ltree && nested(_ltree,other._ltree) ) - return stop; // Found an exit, not an infinite loop + return fun; // Found an exit, not an infinite loop } x = x.idom(); } @@ -52,7 +52,7 @@ public class LoopNode extends RegionNode { setDef(2,t); // True continues loop, False (never) exits loop ReturnNode ret = fun.ret(); iff._ltree = t._ltree = _ltree; - ret._ltree = f._ltree = stop._ltree; + ret._ltree = f._ltree = fun._ltree; // Now fold control into the exit. Might have 1 valid exit, or an // XCtrl or a bunch of prior NeverNode exits. @@ -72,7 +72,7 @@ public class LoopNode extends RegionNode { expr instanceof PhiNode prez && prez.region()==r ) ) { // Nope, insert an aligned exit layer RegionNode r = new RegionNode(_loc,null,ctrl).init(); - ctrl = r; r._ltree = stop._ltree; + ctrl = r; r._ltree = fun._ltree; mem = new BulkMemPhiNode(ScopeNode.MEM0,r,mem).init(); expr = new PhiNode(r,expr).init(); } @@ -91,7 +91,7 @@ public class LoopNode extends RegionNode { ret._type = null; // This may LIFT the Return type, from [XCtrl,mem,expr] to [Ctrl,mem,expr] ret.setType(ret.compute()); - return stop; + return fun; } private static boolean nested(LoopTree inner, LoopTree outer) { diff --git a/chapter24/src/test/java/com/seaofnodes/simple/Chapter18Test.java b/chapter24/src/test/java/com/seaofnodes/simple/Chapter18Test.java index 6e027312..02d4df6b 100644 --- a/chapter24/src/test/java/com/seaofnodes/simple/Chapter18Test.java +++ b/chapter24/src/test/java/com/seaofnodes/simple/Chapter18Test.java @@ -11,6 +11,41 @@ import static org.junit.Assert.*; import static org.junit.Assert.fail; public class Chapter18Test { + @Test public void testNeverExitLoopDepth() { + String[] sources = { + "if(arg) while(1) {} return 7;", + "if(arg==1) while(1) {} if(arg==2) while(1) {} return 7;", + "while(1) {}", + "int x=0; while(arg) { if(arg==2) while(1) { x++; } x++; arg--; } return x;" + }; + for( String src : sources ) { + CodeGen code = new CodeGen(src).driver(CodeGen.Phase.LoopTree); + int[] nevers = {0}; + code._stop.walk(n -> { + if( n instanceof FunNode fun ) + assertEquals("Function entry is outside its loops",0,fun.loopDepth()); + if( n instanceof ReturnNode ret ) { + assertEquals(ret.fun().loopDepth(),ret.loopDepth()); + assertEquals(ret.fun().loopDepth(),ret.cfg0().loopDepth()); + } + if( n instanceof LoopNode loop && !(loop instanceof StartNode) && + loop.back() instanceof CProjNode back && back.in(0) instanceof NeverNode never ) { + nevers[0]++; + assertSame(loop,never.loop()); + assertSame(loop,back.loop()); + CProjNode exit = never.cproj(1-back._idx); + CFGNode fun = loop; + while( !(fun instanceof FunNode) ) fun=fun.idom(); + assertSame(fun.loop(),exit.loop()); + assertEquals(fun.loopDepth(),exit.loopDepth()); + assertTrue(loop.loopDepth()>fun.loopDepth()); + } + return null; + }); + assertTrue("Exercise a synthetic exit",nevers[0]>0); + } + } + @Test public void testFunctionLocalConstantChains() { String src = "val f = { int x -> x ? f(x-1)*305420988+x/305420988 : 1; }; "+ "val g = { int x -> x ? g(x-1)/305420988+x*305420988 : 1; }; "+ diff --git a/chapter24/src/test/java/com/seaofnodes/simple/Chapter20Test.java b/chapter24/src/test/java/com/seaofnodes/simple/Chapter20Test.java index 2035ef9b..937e24e6 100644 --- a/chapter24/src/test/java/com/seaofnodes/simple/Chapter20Test.java +++ b/chapter24/src/test/java/com/seaofnodes/simple/Chapter20Test.java @@ -11,6 +11,38 @@ import org.junit.Test; import static org.junit.Assert.*; public class Chapter20Test { + @Test public void testAllocatorTopPhi() { com.seaofnodes.simple.codegen.RegAllocTestSupport.topPhi(); } + + @Test public void testNeverReturnAllocation() { + String[] sources = { + // A real integer return merged with a synthetic exit. + "if(arg) while(1) {} return arg+1;", + // TOP must not widen a non-null pointer or constrain a float register. + "struct S { int x; }; S !s=new S; if(arg) while(1) {} return s;", + "if(arg) while(1) {} return 1.5;", + // Several synthetic exits into the same return. + "if(arg==1) while(1) {} if(arg==2) while(1) {} return arg+3;", + // No real return, including a merge of only synthetic exits. + "while(1) { arg+=1; }", + "if(arg) while(1) {} while(1) {}", + // Loop-carried memory and scalar self-conflicts exercise spilling. + "struct S { int x; int y; }; S !a=new S; if(arg) while(1) { a.x+=arg; a.y+=a.x; } return a.x+a.y;" + }; + for( String target : new String[]{"x86_64_v2","riscv","arm"} ) + for( String src : sources ) { + CodeGen code = new CodeGen(src).driver(CodeGen.Phase.RegAlloc,target,"SystemV"); + com.seaofnodes.simple.codegen.RegAllocTestSupport.checkRegisters(code); + assertNotNull(code._stop.walk(n -> { + if( n._type!=com.seaofnodes.simple.type.Type.TOP ) return null; + assertEquals(-1,code._regAlloc.regnum(n)); + for( var use : n.outs() ) + assertFalse(use instanceof com.seaofnodes.simple.node.SplitNode); + return n; + })); + code.encode(); + } + } + @Test public void testAllocatorFixedNeighbor() throws Exception { com.seaofnodes.simple.codegen.RegAllocTestSupport.uncoloredFixedNeighbor(); } @Test public void testNarrowStoreMasks() { diff --git a/chapter24/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java b/chapter24/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java index c5ad164e..e83e3c0e 100644 --- a/chapter24/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java +++ b/chapter24/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java @@ -142,8 +142,6 @@ public class MemoryEncodingTest { @Test public void testNeverMemory() { // A synthetic exit must retain both precise slices of a no-exit loop. - // Stop at scheduling: the existing allocator cannot coalesce TOP on - // the synthetic scalar return arm. for( String target : new String[]{"x86_64_v2","riscv","arm"} ) { CodeGen code = new CodeGen(""" struct S { int x; int y; }; @@ -161,7 +159,9 @@ public class MemoryEncodingTest { } return null; })); - code.instSelect(target,"SystemV").GCM().localSched(); + code.instSelect(target,"SystemV").GCM().localSched().regAlloc(); + RegAllocTestSupport.checkRegisters(code); + code.encode(); } } diff --git a/chapter24/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java b/chapter24/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java index 0ccd9741..1ffdb3d0 100644 --- a/chapter24/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java +++ b/chapter24/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java @@ -171,6 +171,28 @@ public class RegAllocTestSupport { } } + public static void topPhi() { + // Either arm can be the synthetic exit. Both predecessors share a + // block here so making TOP live would conflict with the real value. + for( int slot=1; slot<=2; slot++ ) { + CodeGen code = graph(); + RegAlloc alloc = new RegAlloc(code); + Op def = new Op(A,null,null,false,code._start); + Node top = new ConstantNode(com.seaofnodes.simple.type.Type.TOP); + RegionNode region = new RegionNode(null,code._start,code._start); + PhiNode phi = new PhiNode("value",TypeInteger.BOT,region,slot==1 ? top : def,slot==2 ? top : def); + phi._type = TypeInteger.BOT; + new Op(null,A,null,false,region,phi); + code._cfg.add(region); + assertTrue(BuildLRG.run(0,alloc)); + assertNull(alloc.lrg(top)); + assertSame(alloc.lrg(def),alloc.lrg(phi)); + assertTrue(IFG.build(0,alloc)); + alloc.insertBefore(phi,slot,"test",(byte)0,alloc.lrg(phi)); + assertSame(top,phi.in(slot)); + } + } + public static void checkRegisters(CodeGen code) { assertTrue(code._regAlloc.verifyFunctionLocalEdges()); for( CFGNode bb : code._cfg ) @@ -186,7 +208,10 @@ public class RegAllocTestSupport { } if( n instanceof PhiNode && code._regAlloc.regnum(n)>=0 ) for( int i=n instanceof ParmNode ? 2 : 1; i<n.nIns(); i++ ) - assertEquals(code._regAlloc.regnum(n),code._regAlloc.regnum(n.in(i))); + if( n.in(i)._type==com.seaofnodes.simple.type.Type.TOP ) + assertNull(code._regAlloc.lrg(n.in(i))); + else + assertEquals(code._regAlloc.regnum(n),code._regAlloc.regnum(n.in(i))); } } |