8327963: C2: fix construction of memory graph around Initialize node to prevent incorrect execution if allocation is removed

src/hotspot/share/opto/macro.cpp

@@ -1603,7 +1603,9 @@ void PhaseMacroExpand::expand_initialize_membar(AllocateNode* alloc, InitializeN
       // No InitializeNode or no stores captured by zeroing
       // elimination. Simply add the MemBarStoreStore after object
       // initialization.
-      // See comment below in this if's other branch that explains why a raw memory MemBar is good enough.
+      // See comment below in this if's other branch that explains why a raw memory MemBar is good enough. If init is
+      // null, this allocation does have an InitializeNode but this logic can't locate it (see comment in
+      // PhaseMacroExpand::initialize_object()).
       MemBarNode* mb = MemBarNode::make(C, Op_MemBarStoreStore, Compile::AliasIdxRaw);
       transform_later(mb);
 

src/utils/IdealGraphVisualizer/ServerCompiler/src/main/java/com/sun/hotspot/igv/servercompiler/ServerCompilerScheduler.java

@@ -653,7 +653,9 @@ private static boolean isPhi(Node n) {
     }
 
     private static boolean isProj(Node n) {
-        return hasName(n, "Proj") || hasName(n, "MachProj");
+        return hasName(n, "Proj") ||
+               hasName(n, "MachProj") ||
+               hasName(n, "NarrowMemProj");
     }
 
     private static boolean isParm(Node n) {

src/utils/IdealGraphVisualizer/ServerCompiler/src/main/resources/com/sun/hotspot/igv/servercompiler/filters/condenseGraph.filter

@@ -53,6 +53,7 @@ split(and([matches("name", "Parm|MachProj"),
 
 // Combine single-input nodes.
 combine(anyNode, matches("name", "Proj|IfFalse|IfTrue|JProj|MachProj|JumpProj|CatchProj|Parm"));
+combine(anyNode, matches("name", "NarrowMemProj"), ["N"]);
 combine(anyNode, matches("name", "SCMemProj"), ["SCM"]);
 combine(matches("name", "SubTypeCheck|Cmp.*"), matches("name", "Bool"), ["[dump_spec]"]);
 combine(anyNode, matches("name", "Decode(N|NarrowPtr|NKlass)"), ["DC"]);

test/hotspot/jtreg/compiler/escapeAnalysis/TestIterativeEA.java

@@ -48,9 +48,13 @@ public static void main(String[] args) throws Exception {
     System.out.println(analyzer.getOutput());
 
     analyzer.shouldHaveExitValue(0);
-    analyzer.shouldContain("++++ Eliminated: 26 Allocate");
-    analyzer.shouldContain("++++ Eliminated: 51 Allocate");
-    analyzer.shouldContain("++++ Eliminated: 84 Allocate");
+    analyzer.shouldMatch(
+            "(?s)" + // Let .* also match line terminators.
+            "Eliminated: \\d+ Allocate" +
+            ".*" +
+            "Eliminated: \\d+ Allocate" +
+            ".*" +
+            "Eliminated: \\d+ Allocate");
   }
 
   static class A {