From 2b0a59d89098aef40b4400771587b6691810f97b Mon Sep 17 00:00:00 2001
From: ReinUsesLisp <reinuseslisp@airmail.cc>
Date: Sat, 5 Jan 2019 23:58:43 -0300
Subject: [PATCH] Add OpSwitch

---
 include/sirit/sirit.h     |  5 +++++
 src/instructions/flow.cpp | 16 ++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/include/sirit/sirit.h b/include/sirit/sirit.h
index 253e152..eded07e 100644
--- a/include/sirit/sirit.h
+++ b/include/sirit/sirit.h
@@ -192,6 +192,11 @@ class Module {
                            std::uint32_t true_weight = 0,
                            std::uint32_t false_weight = 0);
 
+    /// Multi-way branch to one of the operand label.
+    Id OpSwitch(Id selector, Id default_label,
+                const std::vector<Literal>& literals,
+                const std::vector<Id>& labels);
+
     /// Returns with no value from a function with void return type.
     Id OpReturn();
 
diff --git a/src/instructions/flow.cpp b/src/instructions/flow.cpp
index 8ff856e..4c0036f 100644
--- a/src/instructions/flow.cpp
+++ b/src/instructions/flow.cpp
@@ -7,6 +7,7 @@
 #include "common_types.h"
 #include "op.h"
 #include "sirit/sirit.h"
+#include <cassert>
 #include <vector>
 
 namespace Sirit {
@@ -51,6 +52,21 @@ Id Module::OpBranchConditional(Id condition, Id true_label, Id false_label,
     return AddCode(std::move(op));
 }
 
+Id Module::OpSwitch(Id selector, Id default_label,
+                    const std::vector<Literal>& literals,
+                    const std::vector<Id>& labels) {
+    const std::size_t size = literals.size();
+    assert(literals.size() == labels.size());
+    auto op{std::make_unique<Op>(spv::Op::OpSwitch)};
+    op->Add(selector);
+    op->Add(default_label);
+    for (std::size_t i = 0; i < size; ++i) {
+        op->Add(literals[i]);
+        op->Add(labels[i]);
+    }
+    return AddCode(std::move(op));
+}
+
 Id Module::OpReturn() { return AddCode(spv::Op::OpReturn); }
 
 Id Module::OpReturnValue(Id value) {