diff --git a/pinpoint/pinpoint_config.h b/pinpoint/pinpoint_config.h
index b7f4afe..e73004a 100644
--- a/pinpoint/pinpoint_config.h
+++ b/pinpoint/pinpoint_config.h
@@ -2,3 +2,4 @@
 
 #define SPSLR_ATTRIBUTE "spslr"
 #define SPSLR_PINPOINT_STAGE0_SEPARATOR "__spslr_offsetof"
+#define SPSLR_PINPOINT_STAGE1_SEPARATOR "__spslr_pin" /* suffixed with "_<uid>" */
diff --git a/pinpoint/stage1/asm_offset_pass.cpp b/pinpoint/stage1/asm_offset_pass.cpp
index 399fb23..df577cc 100644
--- a/pinpoint/stage1/asm_offset_pass.cpp
+++ b/pinpoint/stage1/asm_offset_pass.cpp
@@ -1,8 +1,95 @@
 #include <stage1.h>
-#include <stage0.h>
+#include <unordered_map>
+
+#include <pinpoint_error.h>
+#include <pinpoint_config.h>
+
+static UID next_separator_uid = 0;
+static std::unordered_map<UID, S1Separator> separators;
+
+static char asm_str_buf[1024];
+
+static const char* make_asm_noarch(UID uid) {
+	snprintf(asm_str_buf, sizeof(asm_str_buf), SPSLR_PINPOINT_STAGE1_SEPARATOR "_%lu:", uid);
+	return nullptr;
+}
+
+static const char* make_asm_x86_64(UID uid) {
+	// Asm has 1 output (%0) and 2 inputs for target (%1) and offset (%2)
+	snprintf(asm_str_buf, sizeof(asm_str_buf), SPSLR_PINPOINT_STAGE1_SEPARATOR "_%lu: mov %2, %0", uid);
+	return asm_str_buf;
+}
+
+static const char* make_asm(UID uid, S1Separator::ARCH& arch) {
+#if defined(__x86_64__) || defined(__amd64__)
+	arch = S1Separator::X86_64;
+	return make_asm_x86_64(uid);
+#else
+	arch = S1Separator::NONE;
+	return make_asm_noarch(uid);
+#endif
+}
+
+static tree make_asm_operand(const char* constraint_text, tree operand_tree) {
+	tree constraint_str = build_string(strlen (constraint_text) + 1, constraint_text);
+	tree inner_list = build_tree_list(integer_zero_node, constraint_str);
+	tree outer_list = build_tree_list(inner_list, operand_tree);
+	return outer_list;
+}
+
+static gimple* make_stage1_separator(tree lhs, UID target, std::size_t offset) {
+	if (!lhs)
+		return nullptr;
+
+	UID uid = next_separator_uid++;
+
+	S1Separator separator;
+	separator.target = target;
+	separator.offset = offset;
+
+	const char* asm_str = make_asm(uid, separator.arch);
+	if (!asm_str)
+		pinpoint_fatal("make_stage1_separator failed to generate asm string");
+
+	tree arg0 = build_int_cst(size_type_node, target);
+	tree arg1 = build_int_cst(size_type_node, offset);
+
+	vec<tree, va_gc>* outputs = NULL;
+	vec<tree, va_gc>* inputs = NULL;
+
+	vec_safe_push(outputs, make_asm_operand("=r", lhs));
+	vec_safe_push(inputs, make_asm_operand("i", arg0));
+	vec_safe_push(inputs, make_asm_operand("i", arg1));
+
+	gasm* new_gasm = gimple_build_asm_vec(ggc_strdup(asm_str), inputs, outputs, NULL, NULL);
+	if (!new_gasm)
+		return nullptr;
+
+	SSA_NAME_DEF_STMT(lhs) = new_gasm;
+
+	separators.emplace(uid, separator);
+	return new_gasm;
+}
 
 static void separator_assemble_maybe(gimple_stmt_iterator* gsi) {
-	// TODO
+	if (!gsi)
+		return;
+
+	gimple* stmt = gsi_stmt(*gsi);
+	if (!stmt)
+		return;
+
+	UID target;
+	std::size_t offset;
+
+	if (!is_stage0_separator(stmt, target, offset))
+		return;
+
+	gimple* replacement = make_stage1_separator(gimple_call_lhs(stmt), target, offset);
+	if (!replacement)
+		pinpoint_fatal();
+
+	gsi_replace(gsi, replacement, true);
 }
 
 static const pass_data asm_offset_pass_data = {
diff --git a/pinpoint/stage1/stage1.h b/pinpoint/stage1/stage1.h
index b6d9236..211e484 100644
--- a/pinpoint/stage1/stage1.h
+++ b/pinpoint/stage1/stage1.h
@@ -1,7 +1,17 @@
 #pragma once
 
+#include <stage0.h>
 #include <safe-gimple.h>
 
+struct S1Separator {
+	enum ARCH {
+		NONE, X86_64
+	} arch;
+
+	UID target;
+	std::size_t offset;
+};
+
 struct asm_offset_pass : gimple_opt_pass {
 	asm_offset_pass(gcc::context* ctxt);
 	unsigned int execute(function* fn) override;
diff --git a/subject/CMakeLists.txt b/subject/CMakeLists.txt
index 90598c1..3930930 100644
--- a/subject/CMakeLists.txt
+++ b/subject/CMakeLists.txt
@@ -1,4 +1,4 @@
 add_executable(subject main.c)
 add_dependencies(subject spslr_pinpoint spslr_finalize spslr_selfpatch)
 target_link_libraries(subject PRIVATE spslr_selfpatch)
-target_compile_options(subject PRIVATE -fplugin=$<TARGET_FILE:spslr_pinpoint> -fdump-tree-separate_offset)
+target_compile_options(subject PRIVATE -fplugin=$<TARGET_FILE:spslr_pinpoint> -fdump-tree-separate_offset -fdump-tree-asm_offset)