Merge pull request #224 from WebAssembly/spec-updates

Spec updates

11 files changed, 141 insertions, 29 deletions

diff --git a/src/asm2wasm.h b/src/asm2wasm.h
index c13c847e7..be11344b2 100644
--- a/src/asm2wasm.h
+++ b/src/asm2wasm.h
@@ -28,6 +28,7 @@
 #include "shared-constants.h"
 #include "asm_v_wasm.h"
 #include "pass.h"
+#include "ast_utils.h"
 
 namespace wasm {
 
@@ -66,17 +67,6 @@ struct AstStackHelper {
 
 std::vector<Ref> AstStackHelper::astStack;
 
-struct BreakSeeker : public WasmWalker<BreakSeeker> {
-  IString target; // look for this one
-  size_t found;
-
-  BreakSeeker(IString target) : target(target), found(false) {}
-
-  void visitBreak(Break *curr) {
-    if (curr->name == target) found++;
-  }
-};
-
 //
 // Asm2WasmPreProcessor - does some initial parsing/processing
 // of asm.js code.
@@ -431,6 +421,7 @@ private:
     if (expression->is<Block>()) return expression->dyn_cast<Block>();
     auto ret = allocator.alloc<Block>();
     ret->list.push_back(expression);
+    ret->finalize();
     return ret;
   }
 
@@ -1154,7 +1145,7 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
             select->condition = isNegative;
             select->type = i32;
             block->list.push_back(select);
-            block->type = i32;
+            block->finalize();
             return block;
           } else if (value->type == f32 || value->type == f64) {
             auto ret = allocator.alloc<Unary>();
@@ -1237,6 +1228,7 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
           block = allocator.alloc<Block>();
           block->name = name;
           block->list.push_back(ret);
+          block->finalize();
           ret = block;
         }
       }
@@ -1279,6 +1271,7 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
         auto body = allocator.alloc<Block>();
         body->list.push_back(condition);
         body->list.push_back(process(ast[2]));
+        body->finalize();
         ret->body = body;
       }
       // loops do not automatically loop, add a branch back
@@ -1313,6 +1306,7 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
           auto block = allocator.alloc<Block>();
           block->list.push_back(child);
           block->name = stop;
+          block->finalize();
           return block;
         } else {
           auto loop = allocator.alloc<Loop>();
@@ -1376,6 +1370,7 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
       body->list.push_back(condition);
       body->list.push_back(process(fbody));
       body->list.push_back(process(finc));
+      body->finalize();
       ret->body = body;
       // loops do not automatically loop, add a branch back
       Block* block = blockify(ret->body);
@@ -1389,6 +1384,7 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
       // add an outer block for the init as well
       outer->list.push_back(process(finit));
       outer->list.push_back(ret);
+      outer->finalize();
       return outer;
     } else if (what == LABEL) {
       assert(parentLabel.isNull());
@@ -1405,7 +1401,7 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
       auto ret = allocator.alloc<Block>();
       ret->list.push_back(process(ast[1]));
       ret->list.push_back(process(ast[2]));
-      ret->type = ret->list[1]->type;
+      ret->finalize();
       return ret;
     } else if (what == SWITCH) {
       IString name;
@@ -1510,6 +1506,7 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
     for (unsigned i = from; i < ast->size(); i++) {
       block->list.push_back(process(ast[i]));
     }
+    block->finalize();
     return block;
   };
   // body
diff --git a/src/ast_utils.h b/src/ast_utils.h
new file mode 100644
index 000000000..df2ffe578
--- /dev/null
+++ b/src/ast_utils.h
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2016 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.
+ */
+
+#ifndef wasm_ast_utils_h
+#define wasm_ast_utils_h
+
+#include "wasm.h"
+
+namespace wasm {
+
+struct BreakSeeker : public WasmWalker<BreakSeeker> {
+  Name target; // look for this one
+  size_t found;
+
+  BreakSeeker(Name target) : target(target), found(false) {}
+
+  void visitBreak(Break *curr) {
+    if (curr->name == target) found++;
+  }
+
+  static bool has(Expression* tree, Name target) {
+    BreakSeeker breakSeeker(target);
+    breakSeeker.walk(tree);
+    return breakSeeker.found > 0;
+  }
+};
+
+} // namespace wasm
+
+#endif // wasm_ast_utils_h
diff --git a/src/passes/LowerCase.cpp b/src/passes/LowerCase.cpp
index f890de411..c0ab8d235 100644
--- a/src/passes/LowerCase.cpp
+++ b/src/passes/LowerCase.cpp
@@ -84,11 +84,13 @@ struct LowerCase : public WalkerPass<WasmWalker<LowerCase, void>> {
     if (curr->cases.size() == 0) return;
     auto top = allocator->alloc<Block>();
     top->list.push_back(curr);
+    top->finalize();
     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);
+      next->finalize();
       top = next;
     }
     curr->cases.clear();
diff --git a/src/passes/LowerIfElse.cpp b/src/passes/LowerIfElse.cpp
index fa575d87d..922a294d2 100644
--- a/src/passes/LowerIfElse.cpp
+++ b/src/passes/LowerIfElse.cpp
@@ -49,7 +49,7 @@ struct LowerIfElse : public WalkerPass<WasmWalker<LowerIfElse, void>> {
       block->name = name;
       block->list.push_back(curr);
       block->list.push_back(curr->ifFalse);
-      block->type = curr->type;
+      block->finalize();
       curr->ifFalse = nullptr;
       auto break_ = allocator->alloc<Break>();
       break_->name = name;
diff --git a/src/passes/LowerInt64.cpp b/src/passes/LowerInt64.cpp
index 58e56cba6..7af7443e5 100644
--- a/src/passes/LowerInt64.cpp
+++ b/src/passes/LowerInt64.cpp
@@ -112,7 +112,7 @@ struct LowerInt64 : public Pass {
       ret->list.push_back(curr);
       ret->list.push_back(set);
       ret->list.push_back(low); // so the block returns the low bits
-      ret->type = i32;
+      ret->finalize();
       fixes[ret] = high;
       replaceCurrent(ret);
     }
@@ -132,6 +132,7 @@ struct LowerInt64 : public Pass {
       set->type = value->type;
       ret->list.push_back(set);
     }
+    ret->finalize();
     return ret;
   }
 
diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index f365db02f..e8e917a6e 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -65,11 +65,22 @@ struct PrintSExpression : public WasmVisitor<PrintSExpression, void> {
     decIndent();
   }
   void visitIf(If *curr) {
-    printOpening(o, curr->ifFalse ? "if_else" : "if");
+    printOpening(o, "if");
     incIndent();
     printFullLine(curr->condition);
-    printFullLine(curr->ifTrue);
-    if (curr->ifFalse) printFullLine(curr->ifFalse);
+    // ifTrue and False have implict blocks, avoid printing them if possible
+    if (curr->ifTrue->is<Block>() && curr->ifTrue->dyn_cast<Block>()->name.isNull() && curr->ifTrue->dyn_cast<Block>()->list.size() == 1) {
+      printFullLine(curr->ifTrue->dyn_cast<Block>()->list.back());
+    } else {
+      printFullLine(curr->ifTrue);
+    }
+    if (curr->ifFalse) {
+      if (curr->ifFalse->is<Block>() && curr->ifFalse->dyn_cast<Block>()->name.isNull() && curr->ifFalse->dyn_cast<Block>()->list.size() == 1) {
+        printFullLine(curr->ifFalse->dyn_cast<Block>()->list.back());
+      } else {
+        printFullLine(curr->ifFalse);
+      }
+    }
     decIndent();
   }
   void visitLoop(Loop *curr) {
diff --git a/src/s2wasm.h b/src/s2wasm.h
index 0520d5c3b..2de6cd60f 100644
--- a/src/s2wasm.h
+++ b/src/s2wasm.h
@@ -528,6 +528,7 @@ class S2WasmBuilder {
         last = last->cast<Loop>()->body;
       }
       last->cast<Block>()->list.push_back(curr);
+      last->cast<Block>()->finalize();
     };
     bstack.push_back(func->body);
     std::vector<Expression*> estack;
@@ -1023,6 +1024,7 @@ class S2WasmBuilder {
     for (auto block : loopBlocks) {
       block->name = Name();
     }
+    func->body->dyn_cast<Block>()->finalize();
     wasm.addFunction(func);
     // XXX for now, export all functions
     auto exp = allocator.alloc<Export>();
@@ -1243,6 +1245,7 @@ class S2WasmBuilder {
           call->operands.push_back(param);
         }
         block->list.push_back(call);
+        block->finalize();
       }
     }
   }
diff --git a/src/shared-constants.h b/src/shared-constants.h
index 053aecc83..03409de6e 100644
--- a/src/shared-constants.h
+++ b/src/shared-constants.h
@@ -68,6 +68,8 @@ cashew::IString GLOBAL("global"),
                 CALL_IMPORT("call_import"),
                 CALL_INDIRECT("call_indirect"),
                 BR_IF("br_if"),
+                THEN("then"),
+                ELSE("else"),
                 NEG_INFINITY("-infinity"),
                 NEG_NAN("-nan"),
                 CASE("case"),
diff --git a/src/wasm-binary.h b/src/wasm-binary.h
index 8fc6beb6c..993b4522d 100644
--- a/src/wasm-binary.h
+++ b/src/wasm-binary.h
@@ -1359,9 +1359,7 @@ public:
       curr->list.push_back(expressionStack[i]);
     }
     expressionStack.resize(start);
-    if (curr->list.size() > 0) {
-      curr->type = curr->list.back()->type;
-    }
+    curr->finalize();
     breakStack.pop_back();
   }
   void visitIf(If *curr, uint8_t code) {
diff --git a/src/wasm-s-parser.h b/src/wasm-s-parser.h
index 24ca1b811..f3a28fd1a 100644
--- a/src/wasm-s-parser.h
+++ b/src/wasm-s-parser.h
@@ -29,6 +29,7 @@
 #include "shared-constants.h"
 #include "parsing.h"
 #include "asm_v_wasm.h"
+#include "ast_utils.h"
 
 namespace wasm {
 
@@ -380,6 +381,7 @@ private:
           if (!autoBlock) {
             autoBlock = allocator.alloc<Block>();
             autoBlock->list.push_back(func->body);
+            autoBlock->finalize();
             func->body = autoBlock;
           }
           autoBlock->list.push_back(ex);
@@ -567,6 +569,10 @@ public:
           }
           abort_on(str);
         }
+        case 'e': {
+          if (str[1] == 'l') return makeThenOrElse(s);
+          abort_on(str);
+        }
         case 'g': {
           if (str[1] == 'e') return makeGetLocal(s);
           if (str[1] == 'r') return makeHost(s, HostOp::GrowMemory);
@@ -607,6 +613,7 @@ public:
         }
         case 't': {
           if (str[1] == 'a') return makeSwitch(s); // aka tableswitch
+          if (str[1] == 'h') return makeThenOrElse(s);
           abort_on(str);
         }
         case 'u': {
@@ -688,8 +695,9 @@ private:
   Expression* makeBlock(Element& s) {
     auto ret = allocator.alloc<Block>();
     size_t i = 1;
-    if (s[1]->isStr()) {
-      ret->name = s[1]->str();
+    if (i >= s.size()) return ret; // empty block
+    if (s[i]->isStr()) {
+      ret->name = s[i]->str();
       i++;
     } else {
       ret->name = getPrefixedName("block");
@@ -699,7 +707,21 @@ private:
       ret->list.push_back(parseExpression(s[i]));
     }
     labelStack.pop_back();
-    if (ret->list.size() > 0) ret->type = ret->list.back()->type;
+    ret->finalize();
+    return ret;
+  }
+
+  // Similar to block, but the label is handled by the enclosing if (since there might not be a then or else, ick)
+  Expression* makeThenOrElse(Element& s) {
+    auto ret = allocator.alloc<Block>();
+    size_t i = 1;
+    if (s[1]->isStr()) {
+      i++;
+    }
+    for (; i < s.size(); i++) {
+      ret->list.push_back(parseExpression(s[i]));
+    }
+    ret->finalize();
     return ret;
   }
 
@@ -788,9 +810,38 @@ private:
   Expression* makeIf(Element& s) {
     auto ret = allocator.alloc<If>();
     ret->condition = parseExpression(s[1]);
-    ret->ifTrue = parseExpression(s[2]);
+
+    // ifTrue and ifFalse may get implicit blocks
+    auto handle = [&](const char* title, Element& s) {
+      Name name = getPrefixedName(title);
+      bool explicitThenElse = false;
+      if (s[0]->str() == THEN || s[0]->str() == ELSE) {
+        explicitThenElse = true;
+        if (s[1]->dollared()) {
+          name = s[1]->str();
+        }
+      }
+      labelStack.push_back(name);
+      auto* ret = parseExpression(&s);
+      labelStack.pop_back();
+      if (explicitThenElse) {
+        ret->dyn_cast<Block>()->name = name;
+      } else {
+        // add a block if we must
+        if (BreakSeeker::has(ret, name)) {
+          auto* block = allocator.alloc<Block>();
+          block->name = name;
+          block->list.push_back(ret);
+          block->finalize();
+          ret = block;
+        }
+      }
+      return ret;
+    };
+
+    ret->ifTrue = handle("if-true", *s[2]);
     if (s.size() == 4) {
-      ret->ifFalse = parseExpression(s[3]);
+      ret->ifFalse = handle("if-else", *s[3]);
       ret->finalize();
     }
     return ret;
@@ -802,9 +853,7 @@ private:
     for (; i < s.size() && i < stopAt; i++) {
       ret->list.push_back(parseExpression(s[i]));
     }
-    if (ret->list.size() > 0) {
-      ret->type = ret->list.back()->type;
-    }
+    ret->finalize();
     // Note that we do not name these implicit/synthetic blocks. They
     // are the effects of syntactic sugar, and nothing can branch to
     // them anyhow.
diff --git a/src/wasm.h b/src/wasm.h
index ec2cd469e..ba9d7de3d 100644
--- a/src/wasm.h
+++ b/src/wasm.h
@@ -794,6 +794,12 @@ public:
 
   Name name;
   ExpressionList list;
+
+  void finalize() {
+    if (list.size() > 0) {
+      type = list.back()->type;
+    }
+  }
 };
 
 class If : public Expression {