diff options
Diffstat (limited to 'chapter16/src')
3 files changed, 55 insertions, 1 deletions
diff --git a/chapter16/src/main/java/com/seaofnodes/simple/Parser.java b/chapter16/src/main/java/com/seaofnodes/simple/Parser.java index 41a3fcaa..b4cfaaf3 100644 --- a/chapter16/src/main/java/com/seaofnodes/simple/Parser.java +++ b/chapter16/src/main/java/com/seaofnodes/simple/Parser.java @@ -910,7 +910,7 @@ public class Parser { // Arrays include control, as a proxy for a safety range check // Structs don't need this; they only need a NPE check which is // done via the type system. - //if( base.isAry() ) load.setDef(0,ctrl()); + if( base.isAry() ) load.setDef(0,ctrl()); return parsePostfix(load.peephole()); } diff --git a/chapter16/src/main/java/com/seaofnodes/simple/node/LoadNode.java b/chapter16/src/main/java/com/seaofnodes/simple/node/LoadNode.java index 8d604b28..ab53aa6a 100644 --- a/chapter16/src/main/java/com/seaofnodes/simple/node/LoadNode.java +++ b/chapter16/src/main/java/com/seaofnodes/simple/node/LoadNode.java @@ -122,6 +122,9 @@ public class LoadNode extends MemOpNode { // else ptr.x = e1; : e1; // val = ptr.x; ptr.x = val; if( mem() instanceof MemPhiNode memphi && memphi.region()._type == Type.CONTROL && memphi.nIns()== 3 && + // Retain control on both copies only if it dominates both paths. + // The Region itself, or a later range check, cannot move to its inputs. + (in(0)==null || cfg0().domLCA(memphi.region().idom(this),this)==cfg0()) && off() instanceof ConstantNode ) { // Profit on RHS/Loop backedge if( profit(memphi,2) || diff --git a/chapter16/src/test/java/com/seaofnodes/simple/Chapter15Test.java b/chapter16/src/test/java/com/seaofnodes/simple/Chapter15Test.java index 63bdcce7..90d401f5 100644 --- a/chapter16/src/test/java/com/seaofnodes/simple/Chapter15Test.java +++ b/chapter16/src/test/java/com/seaofnodes/simple/Chapter15Test.java @@ -9,6 +9,57 @@ import static org.junit.Assert.fail; public class Chapter15Test { + @Test public void testArrayLoadDominatingControl() { + String src = """ + int[] a=new int[arg+1]; a[arg]=7; + if(a#>1) { + if(arg==2) a[1]=9; + return a[1]; + } + return 42; + """; + StopNode stop = new Parser(src).parse(); + var load = stop.walk(n -> n instanceof com.seaofnodes.simple.node.LoadNode ld && ld._name.equals("[]") ? ld : null); + org.junit.Assert.assertNotNull(load); + // The parser uses current control as a placeholder for a range check. + // Model an explicit check already performed before the inner diamond: + // both predecessors are below the a#>1 true projection. + var region = (com.seaofnodes.simple.node.RegionNode)load.in(0); + var checked = region.idom().cfg(0); + org.junit.Assert.assertTrue(checked instanceof com.seaofnodes.simple.node.CProjNode); + load.setDef(0,checked); + IterPeeps.iterate(stop).typeCheck(); + org.junit.Assert.assertTrue("Common dominating control permits Phi splitting",load.isDead()); + var split = stop.walk(n -> n instanceof com.seaofnodes.simple.node.LoadNode ld && ld._name.equals("[]") ? ld : null); + org.junit.Assert.assertNotNull(split); + org.junit.Assert.assertSame("The surviving read retains the earlier check",checked,split.in(0)); + stop.iterate(); + assertEquals(42L,Evaluator.evaluate(stop,0)); + assertEquals(7L,Evaluator.evaluate(stop,1)); + assertEquals(9L,Evaluator.evaluate(stop,2)); + } + + + @Test public void testArrayLoadControl() { + // With arg==0, a has length 1 and a[1] must not execute. The memory + // merge must not pull the read above its array-length guard. + String src = """ + int n=1; if(arg) n=2; + int[] a=new int[n]; a[arg]=7; + if(arg) a[1]=9; + if(a#>1) return a[1]; + return 42; + """; + StopNode stop = new Parser(src).parse(); + var load = stop.walk(n -> n instanceof com.seaofnodes.simple.node.LoadNode ld && ld._name.equals("[]") ? ld : null); + org.junit.Assert.assertNotNull(load); + org.junit.Assert.assertNotNull("Element loads carry their range-check control",load.in(0)); + stop.iterate(); + assertEquals(42L,Evaluator.evaluate(stop,0)); + assertEquals(9L,Evaluator.evaluate(stop,1)); + } + + @Ignore @Test public void testJig() { |