JVM IR: clear BindingContext after psi2ir

This helps to reduce peak memory in lowerings/codegen by a lot.

A more robust approach would be to have a separate BindingContext for
each file, and clear each of them after running psi2ir on it. This would
also lower peak memory usage in psi2ir.

Provide a fallback workaround compiler argument
-Xir-do-not-clear-binding-context just in case BindingContext is in fact
used somewhere and it's not caught by tests.

compiler/frontend/src/org/jetbrains/kotlin/checkers/utils/CheckerTestUtil.kt

@@ -51,7 +51,8 @@ import java.util.regex.Pattern
 data class DiagnosticsRenderingConfiguration(
     val platform: String?,
     val withNewInference: Boolean,
-    val languageVersionSettings: LanguageVersionSettings?
+    val languageVersionSettings: LanguageVersionSettings?,
+    val skipDebugInfoDiagnostics: Boolean = false,
 )
 
 object CheckerTestUtil {
@@ -130,18 +131,20 @@ object CheckerTestUtil {
             diagnostics.add(ActualDiagnostic(SyntaxErrorDiagnostic(errorElement), configuration.platform, configuration.withNewInference))
         }
 
-        diagnostics.addAll(
-            getDebugInfoDiagnostics(
-                root,
-                bindingContext,
-                markDynamicCalls,
-                dynamicCallDescriptors,
-                configuration,
-                dataFlowValueFactory,
-                moduleDescriptor,
-                diagnosedRanges
+        if (!configuration.skipDebugInfoDiagnostics) {
+            diagnostics.addAll(
+                getDebugInfoDiagnostics(
+                    root,
+                    bindingContext,
+                    markDynamicCalls,
+                    dynamicCallDescriptors,
+                    configuration,
+                    dataFlowValueFactory,
+                    moduleDescriptor,
+                    diagnosedRanges
+                )
             )
-        )
+        }
 
         return diagnostics
     }

compiler/frontend/src/org/jetbrains/kotlin/resolve/BindingTraceContext.java

@@ -37,11 +37,9 @@ public class BindingTraceContext implements BindingTrace {
     /* package */ final static boolean TRACK_WITH_STACK_TRACES = true;
 
     private final MutableSlicedMap map;
-    @Nullable private final MutableDiagnosticsWithSuppression mutableDiagnostics;
-    @NotNull private final BindingTraceFilter filter;
-
-    private final BindingContext bindingContext = new BindingContext() {
+    private final MutableDiagnosticsWithSuppression mutableDiagnostics;
 
+    private final BindingContext bindingContext = new CleanableBindingContext() {
         @NotNull
         @Override
         public Diagnostics getDiagnostics() {
@@ -76,6 +74,11 @@ public class BindingTraceContext implements BindingTrace {
         public void addOwnDataTo(@NotNull BindingTrace trace, boolean commitDiagnostics) {
             BindingContextUtils.addOwnDataTo(trace, null, commitDiagnostics, map, mutableDiagnostics);
         }
+
+        @Override
+        public void clear() {
+            map.clear();
+        }
     };
 
     public BindingTraceContext() {
@@ -87,7 +90,6 @@ public class BindingTraceContext implements BindingTrace {
     }
 
     public BindingTraceContext(BindingTraceFilter filter, boolean allowSliceRewrite) {
-        //noinspection ConstantConditions
         this(TRACK_REWRITES && !allowSliceRewrite ? new TrackingSlicedMap(TRACK_WITH_STACK_TRACES) : new SlicedMapImpl(allowSliceRewrite), filter);
     }
 
@@ -97,7 +99,6 @@ public class BindingTraceContext implements BindingTrace {
         this.mutableDiagnostics = !filter.getIgnoreDiagnostics()
                                   ? new MutableDiagnosticsWithSuppression(bindingContext, Diagnostics.Companion.getEMPTY())
                                   : null;
-        this.filter = filter;
     }
 
     @TestOnly

compiler/frontend/src/org/jetbrains/kotlin/resolve/CleanableBindingContext.kt

@@ -0,0 +1,13 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.resolve
+
+interface CleanableBindingContext : BindingContext {
+    /**
+     * Removes all recorded data except diagnostics.
+     */
+    fun clear()
+}