From c103e2a445a1e2a523f14936ecadf521f56f182f Mon Sep 17 00:00:00 2001
From: imhameed <imhameed@microsoft.com>
Date: Wed, 2 Jun 2021 07:21:33 -0700
Subject: [PATCH] [mono] Separate LLVM optimization and compilation into two
 separate functions. (#53536)

Dump optimized IR before attempting compilation to machine code. Makes
more information available when debugging.

Split from https://github.com/dotnet/runtime/pull/53132.
---
 src/mono/mono/mini/llvm-jit.cpp | 23 +++++++++++++++++++++--
 src/mono/mono/mini/llvm-jit.h   |  3 +++
 src/mono/mono/mini/mini-llvm.c  | 10 ++++++----
 3 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/src/mono/mono/mini/llvm-jit.cpp b/src/mono/mono/mini/llvm-jit.cpp
index e536896..ed69471 100644
--- a/src/mono/mono/mini/llvm-jit.cpp
+++ b/src/mono/mono/mini/llvm-jit.cpp
@@ -306,6 +306,14 @@ struct MonoLLVMJIT {
 		return ret;
 	}
 
+	void
+	optimize (Function *func)
+	{
+		auto module = func->getParent ();
+		module->setDataLayout (data_layout);
+		fpm.run (*func);
+	}
+
 	gpointer
 	compile (
 		Function *func, int nvars, LLVMValueRef *callee_vars,
@@ -313,7 +321,6 @@ struct MonoLLVMJIT {
 	{
 		auto module = func->getParent ();
 		module->setDataLayout (data_layout);
-		fpm.run (*func);
 		// The lifetime of this module is managed by Mono, not LLVM, so
 		// the `unique_ptr` created here will be released in the
 		// NotifyCompiled callback.
@@ -416,9 +423,15 @@ public:
 		return MangledName;
 	}
 
-	gpointer compile (Function *F, int nvars, LLVMValueRef *callee_vars, gpointer *callee_addrs, gpointer *eh_frame) {
+	void
+	optimize (Function *func)
+	{
 		F->getParent ()->setDataLayout (TM->createDataLayout ());
 		fpm.run(*F);
+	}
+
+	gpointer compile (Function *F, int nvars, LLVMValueRef *callee_vars, gpointer *callee_addrs, gpointer *eh_frame) {
+		F->getParent ()->setDataLayout (TM->createDataLayout ());
 		// TODO: run module wide optimizations, e.g. remove dead globals/functions
 		// Orc uses a shared_ptr to refer to modules so we have to save them ourselves to keep a ref
 		std::shared_ptr<Module> m (F->getParent ());
@@ -565,6 +578,12 @@ mono_llvm_create_ee (LLVMExecutionEngineRef *ee)
 	return NULL;
 }
 
+void
+mono_llvm_optimize_method (LLVMValueRef method)
+{
+	jit->optimize (unwrap<Function> (method));
+}
+
 /*
  * mono_llvm_compile_method:
  *
diff --git a/src/mono/mono/mini/llvm-jit.h b/src/mono/mono/mini/llvm-jit.h
index 0b9a943..2845a65 100644
--- a/src/mono/mono/mini/llvm-jit.h
+++ b/src/mono/mono/mini/llvm-jit.h
@@ -42,6 +42,9 @@ mono_llvm_create_ee (LLVMExecutionEngineRef *ee);
 void
 mono_llvm_dispose_ee (MonoEERef *mono_ee);
 
+void
+mono_llvm_optimize_method (LLVMValueRef method);
+
 gpointer
 mono_llvm_compile_method (MonoEERef mono_ee, MonoCompile *cfg, LLVMValueRef method, int nvars, LLVMValueRef *callee_vars, gpointer *callee_addrs, gpointer *eh_frame);
 
diff --git a/src/mono/mono/mini/mini-llvm.c b/src/mono/mono/mini/mini-llvm.c
index 65b74f9..ffe0a83 100644
--- a/src/mono/mono/mini/mini-llvm.c
+++ b/src/mono/mono/mini/mini-llvm.c
@@ -13597,10 +13597,7 @@ llvm_jit_finalize_method (EmitContext *ctx)
 	while (g_hash_table_iter_next (&iter, NULL, (void**)&var))
 		callee_vars [i ++] = var;
 
-	mono_codeman_enable_write ();
-	cfg->native_code = (guint8*)mono_llvm_compile_method (ctx->module->mono_ee, cfg, ctx->lmethod, nvars, callee_vars, callee_addrs, &eh_frame);
-	mono_llvm_remove_gc_safepoint_poll (ctx->lmodule);
-	mono_codeman_disable_write ();
+	mono_llvm_optimize_method (ctx->lmethod);
 	if (cfg->verbose_level > 1) {
 		g_print ("\n*** Optimized LLVM IR for %s ***\n", mono_method_full_name (cfg->method, TRUE));
 		if (cfg->compile_aot) {
@@ -13611,6 +13608,11 @@ llvm_jit_finalize_method (EmitContext *ctx)
 		g_print ("***\n\n");
 	}
 
+	mono_codeman_enable_write ();
+	cfg->native_code = (guint8*)mono_llvm_compile_method (ctx->module->mono_ee, cfg, ctx->lmethod, nvars, callee_vars, callee_addrs, &eh_frame);
+	mono_llvm_remove_gc_safepoint_poll (ctx->lmodule);
+	mono_codeman_disable_write ();
+
 	decode_llvm_eh_info (ctx, eh_frame);
 
 	// FIXME:
-- 
2.7.4