Merge pull request #201 from WebAssembly/lower-case

Add a optional pass to lower cases

4 files changed, 272 insertions, 0 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index e3ec72c6e..d927771d6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -76,6 +76,7 @@ ADD_LIBRARY(support STATIC ${support_SOURCES})
 SET(binaryen-shell_SOURCES
   src/binaryen-shell.cpp
   src/pass.cpp
+  src/passes/LowerCase.cpp
   src/passes/LowerIfElse.cpp
   src/passes/MergeBlocks.cpp
   src/passes/NameManager.cpp
diff --git a/src/passes/LowerCase.cpp b/src/passes/LowerCase.cpp
new file mode 100644
index 000000000..50c370bdc
--- /dev/null
+++ b/src/passes/LowerCase.cpp
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2015 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//
+// Lowers switch cases out into blocks,
+//
+/*
+    (tableswitch $switch$0
+      (i32.sub
+        (get_local $x)
+        (i32.const 1)
+      )
+      (table (case $switch-case$1) (case $switch-case$2)) (case $switch-default$3)
+      (case $switch-case$1
+        (return
+          (i32.const 1)
+        )
+      )
+      (case $switch-case$2
+        (return
+          (i32.const 2)
+        )
+      )
+      (case $switch-default$3
+        (nop)
+      )
+    )
+
+  into
+
+    (block $forswitch$switch$0
+      (block $switch-case$3
+        (block $switch-case$2
+          (block $switch-case$1
+            (tableswitch $switch$0
+              (i32.sub
+                (get_local $x)
+                (i32.const 1)
+              )
+              (table (br $switch-case$1) (br $switch-case$2)) (br $switch-default$3)
+            )
+          )
+          (return
+            (i32.const 1)
+          )
+        )
+        (return
+          (i32.const 2)
+        )
+      )
+      (nop)
+    )
+*/
+
+
+#include <memory>
+
+#include <wasm.h>
+#include <pass.h>
+
+namespace wasm {
+
+struct LowerCase : public WalkerPass<WasmWalker<LowerCase, void>> {
+  MixedArena* allocator;
+
+  void prepare(PassRunner* runner, Module *module) override {
+    allocator = runner->allocator;
+  }
+
+  void visitSwitch(Switch *curr) {
+    if (curr->cases.size() == 0) return;
+    auto top = allocator->alloc<Block>();
+    top->list.push_back(curr);
+    for (auto& c : curr->cases) {
+      top->name = c.name;
+      auto next = allocator->alloc<Block>();
+      next->list.push_back(top);
+      next->list.push_back(c.body);
+      top = next;
+    }
+    curr->cases.clear();
+    top->name = Name(std::string("forswitch$") + curr->name.str);
+    replaceCurrent(top);
+  }
+};
+
+static RegisterPass<LowerCase> registerPass("lower-case", "lowers cases into blocks");
+
+} // namespace wasm
diff --git a/test/passes/lower-case.txt b/test/passes/lower-case.txt
new file mode 100644
index 000000000..82651da23
--- /dev/null
+++ b/test/passes/lower-case.txt
@@ -0,0 +1,88 @@
+(module
+  (memory 0)
+  (func $switcher (param $x i32) (result i32)
+    (block $forswitch$switch$0
+      (block $switch-default$3
+        (block $switch-case$2
+          (block $switch-case$1
+            (tableswitch $switch$0
+              (i32.sub
+                (get_local $x)
+                (i32.const 1)
+              )
+              (table (br $switch-case$1) (br $switch-case$2)) (br $switch-default$3)
+            )
+          )
+          (return
+            (i32.const 1)
+          )
+        )
+        (return
+          (i32.const 2)
+        )
+      )
+      (nop)
+    )
+    (block $forswitch$switch$4
+      (block $switch-default$7
+        (block $switch-case$6
+          (block $switch-case$5
+            (tableswitch $switch$4
+              (i32.sub
+                (get_local $x)
+                (i32.const 5)
+              )
+              (table (br $switch-case$6) (br $switch-default$7) (br $switch-default$7) (br $switch-default$7) (br $switch-default$7) (br $switch-default$7) (br $switch-default$7) (br $switch-case$5)) (br $switch-default$7)
+            )
+          )
+          (return
+            (i32.const 121)
+          )
+        )
+        (return
+          (i32.const 51)
+        )
+      )
+      (nop)
+    )
+    (block $forswitch$label$break$Lout
+      (block $switch-default$16
+        (block $switch-case$15
+          (block $switch-case$12
+            (block $switch-case$9
+              (block $switch-case$8
+                (tableswitch $label$break$Lout
+                  (i32.sub
+                    (get_local $x)
+                    (i32.const 2)
+                  )
+                  (table (br $switch-case$15) (br $switch-default$16) (br $switch-default$16) (br $switch-case$12) (br $switch-default$16) (br $switch-default$16) (br $switch-default$16) (br $switch-default$16) (br $switch-case$9) (br $switch-default$16) (br $switch-case$8)) (br $switch-default$16)
+                )
+              )
+              (br $label$break$Lout)
+            )
+            (br $label$break$Lout)
+          )
+          (block $block0
+            (loop $while-out$10 $while-in$11
+              (br $while-out$10)
+              (br $while-in$11)
+            )
+            (br $label$break$Lout)
+          )
+        )
+        (block $block1
+          (loop $while-out$13 $while-in$14
+            (br $label$break$Lout)
+            (br $while-in$14)
+          )
+          (br $label$break$Lout)
+        )
+      )
+      (nop)
+    )
+    (return
+      (i32.const 0)
+    )
+  )
+)
diff --git a/test/passes/lower-case.wast b/test/passes/lower-case.wast
new file mode 100644
index 000000000..70cae71a9
--- /dev/null
+++ b/test/passes/lower-case.wast
@@ -0,0 +1,81 @@
+(module
+  (func $switcher (param $x i32) (result i32)
+    (tableswitch $switch$0
+      (i32.sub
+        (get_local $x)
+        (i32.const 1)
+      )
+      (table (case $switch-case$1) (case $switch-case$2)) (case $switch-default$3)
+      (case $switch-case$1
+        (return
+          (i32.const 1)
+        )
+      )
+      (case $switch-case$2
+        (return
+          (i32.const 2)
+        )
+      )
+      (case $switch-default$3
+        (nop)
+      )
+    )
+    (tableswitch $switch$4
+      (i32.sub
+        (get_local $x)
+        (i32.const 5)
+      )
+      (table (case $switch-case$6) (case $switch-default$7) (case $switch-default$7) (case $switch-default$7) (case $switch-default$7) (case $switch-default$7) (case $switch-default$7) (case $switch-case$5)) (case $switch-default$7)
+      (case $switch-case$5
+        (return
+          (i32.const 121)
+        )
+      )
+      (case $switch-case$6
+        (return
+          (i32.const 51)
+        )
+      )
+      (case $switch-default$7
+        (nop)
+      )
+    )
+    (tableswitch $label$break$Lout
+      (i32.sub
+        (get_local $x)
+        (i32.const 2)
+      )
+      (table (case $switch-case$15) (case $switch-default$16) (case $switch-default$16) (case $switch-case$12) (case $switch-default$16) (case $switch-default$16) (case $switch-default$16) (case $switch-default$16) (case $switch-case$9) (case $switch-default$16) (case $switch-case$8)) (case $switch-default$16)
+      (case $switch-case$8
+        (br $label$break$Lout)
+      )
+      (case $switch-case$9
+        (br $label$break$Lout)
+      )
+      (case $switch-case$12
+        (block
+          (loop $while-out$10 $while-in$11
+            (br $while-out$10)
+            (br $while-in$11)
+          )
+          (br $label$break$Lout)
+        )
+      )
+      (case $switch-case$15
+        (block
+          (loop $while-out$13 $while-in$14
+            (br $label$break$Lout)
+            (br $while-in$14)
+          )
+          (br $label$break$Lout)
+        )
+      )
+      (case $switch-default$16
+        (nop)
+      )
+    )
+    (return
+      (i32.const 0)
+    )
+  )
+)