From 44294a051a3cba7cb4b9c3118393fb9c14556cd8 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Fri, 12 Oct 2018 06:14:27 +0200
Subject: [PATCH] - clean up assembly output slightly by only generating labels
 for the opcodes jumped to

---
 src/scripting/vm/jit.cpp      | 25 ++++++++++++++++++++-----
 src/scripting/vm/jit_flow.cpp |  8 ++++----
 src/scripting/vm/jitintern.h  | 23 +++++++++++++++++++++--
 3 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/src/scripting/vm/jit.cpp b/src/scripting/vm/jit.cpp
index 7231f8e590..492b9d2a11 100644
--- a/src/scripting/vm/jit.cpp
+++ b/src/scripting/vm/jit.cpp
@@ -148,13 +148,15 @@ void JitCompiler::Codegen()
 		cc.comment("", 0);
 		cc.comment(lineinfo.GetChars(), lineinfo.Len());
 
-		cc.bind(labels[i]);
+		labels[i].cursor = cc.getCursor();
 		ResetTemp();
 		EmitOpcode();
 
 		pc++;
 	}
 
+	BindLabels();
+
 	cc.endFunc();
 	cc.finalize();
 }
@@ -173,6 +175,22 @@ void JitCompiler::EmitOpcode()
 	}
 }
 
+void JitCompiler::BindLabels()
+{
+	asmjit::CBNode *cursor = cc.getCursor();
+	unsigned int size = labels.Size();
+	for (unsigned int i = 0; i < size; i++)
+	{
+		const OpcodeLabel &label = labels[i];
+		if (label.inUse)
+		{
+			cc.setCursor(label.cursor);
+			cc.bind(label.label);
+		}
+	}
+	cc.setCursor(cursor);
+}
+
 void JitCompiler::Setup()
 {
 	using namespace asmjit;
@@ -245,10 +263,7 @@ void JitCompiler::Setup()
 		regA[i] = cc.newIntPtr(regname.GetChars());
 	}
 
-	int size = sfunc->CodeSize;
-	labels.Resize(size);
-	for (int i = 0; i < size; i++)
-		labels[i] = cc.newLabel();
+	labels.Resize(sfunc->CodeSize);
 
 	// VMCalls[0]++
 	auto vmcallsptr = newTempIntPtr();
diff --git a/src/scripting/vm/jit_flow.cpp b/src/scripting/vm/jit_flow.cpp
index be74bc9406..15177b57d2 100644
--- a/src/scripting/vm/jit_flow.cpp
+++ b/src/scripting/vm/jit_flow.cpp
@@ -5,7 +5,7 @@ void JitCompiler::EmitTEST()
 {
 	int i = (int)(ptrdiff_t)(pc - sfunc->Code);
 	cc.cmp(regD[A], BC);
-	cc.jne(labels[i + 2]);
+	cc.jne(GetLabel(i + 2));
 }
 	
 void JitCompiler::EmitTESTN()
@@ -13,14 +13,14 @@ void JitCompiler::EmitTESTN()
 	int bc = BC;
 	int i = (int)(ptrdiff_t)(pc - sfunc->Code);
 	cc.cmp(regD[A], -bc);
-	cc.jne(labels[i + 2]);
+	cc.jne(GetLabel(i + 2));
 }
 
 void JitCompiler::EmitJMP()
 {
 	auto dest = pc + JMPOFS(pc) + 1;
 	int i = (int)(ptrdiff_t)(dest - sfunc->Code);
-	cc.jmp(labels[i]);
+	cc.jmp(GetLabel(i));
 }
 
 void JitCompiler::EmitIJMP()
@@ -40,7 +40,7 @@ void JitCompiler::EmitIJMP()
 			int target = i + JMPOFS(&sfunc->Code[i]) + 1;
 
 			cc.cmp(val, i);
-			cc.je(labels[target]);
+			cc.je(GetLabel(target));
 		}
 	}
 
diff --git a/src/scripting/vm/jitintern.h b/src/scripting/vm/jitintern.h
index 4ebef501d8..3a9e24adad 100644
--- a/src/scripting/vm/jitintern.h
+++ b/src/scripting/vm/jitintern.h
@@ -39,6 +39,7 @@ private:
 	#undef xx
 
 	void Setup();
+	void BindLabels();
 	void EmitOpcode();
 	void EmitPopFrame();
 
@@ -63,7 +64,7 @@ private:
 
 		auto successLabel = cc.newLabel();
 
-		auto failLabel = labels[i + 2 + JMPOFS(pc + 1)];
+		auto failLabel = GetLabel(i + 2 + JMPOFS(pc + 1));
 
 		jmpFunc(static_cast<bool>(A & CMP_CHECK), failLabel, successLabel);
 
@@ -172,7 +173,25 @@ private:
 	TArray<asmjit::X86Gp> regA;
 	TArray<asmjit::X86Gp> regS;
 
-	TArray<asmjit::Label> labels;
+	struct OpcodeLabel
+	{
+		asmjit::CBNode *cursor = nullptr;
+		asmjit::Label label;
+		bool inUse = false;
+	};
+
+	asmjit::Label GetLabel(size_t pos)
+	{
+		auto &label = labels[pos];
+		if (!label.inUse)
+		{
+			label.label = cc.newLabel();
+			label.inUse = true;
+		}
+		return label.label;
+	}
+
+	TArray<OpcodeLabel> labels;
 
 	const VMOP *pc;
 	VM_UBYTE op;