[Kotlin/Native] Avoid jni overhead when optimizing bitcode.

The phase to eliminate redundant function prologue safepoints
was written in Kotlin which meant that it was performing a lot
of jni calls. Moving the simple optimization to C code speeds
things up dramatically.

On a large project this reduces the time for this phase from
11.8 seconds to 1.4 seconds.

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/BitcodePhases.kt

@@ -324,7 +324,7 @@ internal val removeRedundantSafepointsPhase = makeKonanModuleOpPhase(
         name = "RemoveRedundantSafepoints",
         description = "Remove function prologue safepoints inlined to another function",
         op = { context, _ ->
-            RemoveRedundantSafepointsPass(context).runOnModule(
+            RemoveRedundantSafepointsPass().runOnModule(
                     module = context.generationState.llvm.module,
                     isSafepointInliningAllowed = context.shouldInlineSafepoints()
             )

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/optimizations/RemoveRedundantSafepointsPass.kt

@@ -18,59 +18,8 @@ import org.jetbrains.kotlin.backend.konan.logMultiple
  * Also, if first basic block in function contains call to Kotlin_mm_safePointFunctionPrologue, all other calls would be removed.
  * Also, calls, which are not removed are inlined (except arm32 apple targets)
  */
-internal class RemoveRedundantSafepointsPass(
+internal class RemoveRedundantSafepointsPass {
-        private val loggingContext: LoggingContext
-) {
-    var totalPrologueSafepointsCount = 0
-    var removedPrologueSafepointsCount = 0
-
-    fun runOnFunction(function: LLVMValueRef, isSafepointInliningAllowed: Boolean) {
-        val firstBlock = LLVMGetFirstBasicBlock(function) ?: return
-        val firstBlockHasSafepoint = getInstructions(firstBlock).any { isPrologueSafepointCallsite(it) }
-        getBasicBlocks(function).forEach { bb ->
-            val removeFirst = firstBlockHasSafepoint && bb != firstBlock
-            val prologueSafepointCallsites = getInstructions(bb)
-                    .filter { isPrologueSafepointCallsite(it) }
-                    .toList()
-            totalPrologueSafepointsCount += prologueSafepointCallsites.size
-            prologueSafepointCallsites.drop(if (removeFirst) 0 else 1).forEach {
-                LLVMInstructionEraseFromParent(it)
-                removedPrologueSafepointsCount += 1
-            }
-            if (!removeFirst && isSafepointInliningAllowed) {
-                prologueSafepointCallsites
-                        .firstOrNull()
-                        ?.apply {
-                            if (LLVMIsDeclaration(LLVMGetCalledValue(this)) == 0) {
-                                if (LLVMInlineCall(this) == 0) {
-                                    loggingContext.logMultiple {
-                                        +"Failed to Inline safepoint to ${function.name}"
-                                        +llvm2string(function)
-                                    }
-                                }
-                            }
-                        }
-            }
-        }
-    }
-
-    private fun isPrologueSafepointCallsite(insn: LLVMValueRef): Boolean =
-            (LLVMIsACallInst(insn) != null || LLVMIsAInvokeInst(insn) != null)
-                    && LLVMGetCalledValue(insn)?.name == prologueSafepointFunctionName
-
     fun runOnModule(module: LLVMModuleRef, isSafepointInliningAllowed: Boolean) {
-        totalPrologueSafepointsCount = 0
+        LLVMKotlinRemoveRedundantSafepoints(module, if (isSafepointInliningAllowed) 1 else 0)
-        removedPrologueSafepointsCount = 0
-        getFunctions(module)
-                .filterNot { LLVMIsDeclaration(it) == 1 }
-                .forEach { runOnFunction(it, isSafepointInliningAllowed) }
-        loggingContext.logMultiple {
-               +"Total prologue safepoints: $totalPrologueSafepointsCount"
-               +"Removed prologue safepoints: $removedPrologueSafepointsCount"
-        }
-    }
-
-    companion object {
-        private const val prologueSafepointFunctionName = "Kotlin_mm_safePointFunctionPrologue"
     }
 }

kotlin-native/backend.native/llvm.def

@@ -1,9 +1,9 @@
 headers = llvm-c/Core.h llvm-c/Target.h llvm-c/Analysis.h llvm-c/BitWriter.h \
     llvm-c/BitReader.h llvm-c/Transforms/PassManagerBuilder.h llvm-c/Transforms/IPO.h \
     llvm-c/TargetMachine.h llvm-c/Target.h llvm-c/Linker.h llvm-c/Initialization.h \
-    llvm-c/DebugInfo.h DebugInfoC.h CoverageMappingC.h CAPIExtensions.h
+    llvm-c/DebugInfo.h DebugInfoC.h CoverageMappingC.h CAPIExtensions.h RemoveRedundantSafepoints.h
 
-headerFilter = llvm-c/* llvm-c/**/* DebugInfoC.h CoverageMappingC.h CAPIExtensions.h
+headerFilter = llvm-c/* llvm-c/**/* DebugInfoC.h CoverageMappingC.h CAPIExtensions.h RemoveRedundantSafepoints.h
 
 compilerOpts = -std=c99 \
     -Wall -W -Wno-unused-parameter -Wwrite-strings -Wmissing-field-initializers \

kotlin-native/libllvmext/src/main/cpp/RemoveRedundantSafepoints.cpp

@@ -0,0 +1,84 @@
+/*
+ * Copyright 2010-2022 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+#include <CAPIExtensions.h>
+#include <RemoveRedundantSafepoints.h>
+#include <llvm/IR/Constants.h>
+#include <llvm/IR/Instructions.h>
+
+using namespace llvm;
+
+static constexpr const char* functionPrologueSafepointName = "Kotlin_mm_safePointFunctionPrologue";
+
+static constexpr size_t functionPrologueSafepointNameLength =
+  std::char_traits<char>::length(functionPrologueSafepointName);
+
+static bool InstructionIsPrologueSafepoint(LLVMValueRef instruction) {
+  if (LLVMIsACallInst(instruction) || LLVMIsAInvokeInst(instruction)) {
+    size_t calledNameLength = 0;
+    const char* calledName = LLVMGetValueName2(LLVMGetCalledValue(instruction), &calledNameLength);
+    return functionPrologueSafepointNameLength == calledNameLength &&
+      strncmp(calledName, functionPrologueSafepointName, calledNameLength) == 0;
+  }
+  return false;
+}
+
+static bool BlockHasSafepointInstruction(LLVMBasicBlockRef block) {
+  LLVMValueRef current = LLVMGetFirstInstruction(block);
+  while (current) {
+    if (InstructionIsPrologueSafepoint(current)) {
+      return true;
+    }
+    current = LLVMGetNextInstruction(current);
+  }
+  return false;
+}
+
+static void RemoveOrInlinePrologueSafepointInstructions(
+  LLVMBasicBlockRef block, bool removeFirst, bool isSafepointInliningAllowed) {
+  // Collect safepoint calls to erase and inline.
+  LLVMValueRef toInline = nullptr;
+  std::vector<LLVMValueRef> toErase;
+  bool first = true;
+  LLVMValueRef current = LLVMGetFirstInstruction(block);
+  while (current) {
+    if (InstructionIsPrologueSafepoint(current)) {
+      if (!first || removeFirst) {
+        toErase.push_back(current);
+      } else if (isSafepointInliningAllowed && !LLVMIsDeclaration(LLVMGetCalledValue(current))) {
+        toInline = current;
+      }
+      first = false;
+    }
+    current = LLVMGetNextInstruction(current);
+  }
+  // Perform actual modifications after iteration.
+  for (auto it = toErase.cbegin(); it != toErase.cend(); ++it) {
+    LLVMInstructionEraseFromParent(*it);
+  }
+  if (toInline) {
+    LLVMInlineCall(toInline);
+  }
+}
+
+void LLVMKotlinRemoveRedundantSafepoints(LLVMModuleRef module, int isSafepointInliningAllowed) {
+  bool inliningAllowed = isSafepointInliningAllowed != 0;
+  LLVMValueRef currentFunction = LLVMGetFirstFunction(module);
+  while (currentFunction) {
+    if (!LLVMIsDeclaration(currentFunction)) {
+      LLVMBasicBlockRef firstBlock = LLVMGetFirstBasicBlock(currentFunction);
+      if (firstBlock) {
+        bool firstBlockHasSafepoint = BlockHasSafepointInstruction(firstBlock);
+        RemoveOrInlinePrologueSafepointInstructions(firstBlock, false, inliningAllowed);
+        LLVMBasicBlockRef currentBlock = LLVMGetNextBasicBlock(firstBlock);
+        while (currentBlock) {
+          RemoveOrInlinePrologueSafepointInstructions(currentBlock, firstBlockHasSafepoint, inliningAllowed);
+          currentBlock = LLVMGetNextBasicBlock(currentBlock);
+        }
+      }
+    }
+    currentFunction = LLVMGetNextFunction(currentFunction);
+  }
+}

kotlin-native/libllvmext/src/main/include/RemoveRedundantSafepoints.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2010-2022 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+#ifndef LIBLLVMEXT_REMOVE_REDUNDANT_SAFEPOINTS_H
+#define LIBLLVMEXT_REMOVE_REDUNDANT_SAFEPOINTS_H
+
+#endif // LIBLLVMEXT_REMOVE_REDUNDANT_SAFEPOINTS_H
+
+#include <llvm-c/Core.h>
+#include <llvm-c/Target.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+void LLVMKotlinRemoveRedundantSafepoints(LLVMModuleRef module, int isSafePointInliningAllowed);
+
+# ifdef __cplusplus
+}
+# endif