commit e2688c432fcffff53d7d356d7530a0b139c16286
author Derek Schuff <dschuff@google.com> Tue Mar 14 20:23:22 2017 +0000
committer Derek Schuff <dschuff@google.com> Tue Mar 14 20:23:22 2017 +0000
tree 2b97e836032eaecdaf9f998154ef61ff141975cd
parent 265ca535ab1c208749c05fbbb2d18ddd0047dd65

[WebAssembly] Use LEB encoding for value types

Previously we were using the encoded LEB hex values
for the value types.  This change uses the decoded
negative value and the LEB encoder to write them out.

Differential Revision: https://reviews.llvm.org/D30847

Patch by Sam Clegg

llvm-svn: 297777

llvm/lib/MC/WasmObjectWriter.cpp

diff --git a/llvm/lib/MC/WasmObjectWriter.cpp b/llvm/lib/MC/WasmObjectWriter.cpp
index e61b125..20ace61 100644
--- a/llvm/lib/MC/WasmObjectWriter.cpp
+++ b/llvm/lib/MC/WasmObjectWriter.cpp
@@ -109,6 +109,10 @@
 
   void writeHeader(const MCAssembler &Asm);
 
+  void writeValueType(wasm::ValType Ty) {
+    encodeSLEB128(int32_t(Ty), getStream());
+  }
+
   void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
                         const MCFragment *Fragment, const MCFixup &Fixup,
                         MCValue Target, bool &IsPCRel,
@@ -140,7 +144,7 @@
   assert((Name != nullptr) == (SectionId == wasm::WASM_SEC_CUSTOM) &&
          "Only custom sections can have names");
 
-  write8(SectionId);
+  encodeULEB128(SectionId, getStream());
 
   Section.SizeOffset = getStream().tell();
 
@@ -290,10 +294,10 @@
   enum { Plain, Empty, Tombstone } State;
 
   // The return types of the function.
-  SmallVector<unsigned, 1> Returns;
+  SmallVector<wasm::ValType, 1> Returns;
 
   // The parameter types of the function.
-  SmallVector<unsigned, 4> Params;
+  SmallVector<wasm::ValType, 4> Params;
 
   WasmFunctionType() : State(Plain) {}
 
@@ -317,10 +321,10 @@
   }
   static unsigned getHashValue(const WasmFunctionType &FuncTy) {
     uintptr_t Value = FuncTy.State;
-    for (unsigned Ret : FuncTy.Returns)
-      Value += DenseMapInfo<unsigned>::getHashValue(Ret);
-    for (unsigned Param : FuncTy.Params)
-      Value += DenseMapInfo<unsigned>::getHashValue(Param);
+    for (wasm::ValType Ret : FuncTy.Returns)
+      Value += DenseMapInfo<int32_t>::getHashValue(int32_t(Ret));
+    for (wasm::ValType Param : FuncTy.Params)
+      Value += DenseMapInfo<int32_t>::getHashValue(int32_t(Param));
     return Value;
   }
   static bool isEqual(const WasmFunctionType &LHS,
@@ -756,13 +760,13 @@
     encodeULEB128(FunctionTypes.size(), getStream());
 
     for (WasmFunctionType &FuncTy : FunctionTypes) {
-      write8(wasm::WASM_TYPE_FUNC);
+      encodeSLEB128(wasm::WASM_TYPE_FUNC, getStream());
       encodeULEB128(FuncTy.Params.size(), getStream());
-      for (unsigned Ty : FuncTy.Params)
-        write8(Ty);
+      for (wasm::ValType Ty : FuncTy.Params)
+        writeValueType(Ty);
       encodeULEB128(FuncTy.Returns.size(), getStream());
-      for (unsigned Ty : FuncTy.Returns)
-        write8(Ty);
+      for (wasm::ValType Ty : FuncTy.Returns)
+        writeValueType(Ty);
     }
 
     endSection(Section);
@@ -782,15 +786,15 @@
       encodeULEB128(FieldName.size(), getStream());
       writeBytes(FieldName);
 
-      write8(Import.Kind);
+      encodeULEB128(Import.Kind, getStream());
 
       switch (Import.Kind) {
       case wasm::WASM_EXTERNAL_FUNCTION:
         encodeULEB128(Import.Type, getStream());
         break;
       case wasm::WASM_EXTERNAL_GLOBAL:
-        write8(Import.Type);
-        write8(0); // mutability
+        encodeSLEB128(Import.Type, getStream());
+        encodeULEB128(0, getStream()); // mutability
         break;
       default:
         llvm_unreachable("unsupported import kind");
@@ -820,7 +824,7 @@
   // The number of tables, fixed to 1 for now.
   encodeULEB128(1, getStream());
 
-  write8(wasm::WASM_TYPE_ANYFUNC);
+  encodeSLEB128(wasm::WASM_TYPE_ANYFUNC, getStream());
 
   encodeULEB128(0, getStream());                 // flags
   encodeULEB128(TableElems.size(), getStream()); // initial
@@ -846,7 +850,7 @@
 
     encodeULEB128(Globals.size(), getStream());
     for (const WasmGlobal &Global : Globals) {
-      write8(Global.Type);
+      encodeSLEB128(Global.Type, getStream());
       write8(Global.IsMutable);
 
       write8(wasm::WASM_OPCODE_I32_CONST);
@@ -866,7 +870,7 @@
       encodeULEB128(Export.FieldName.size(), getStream());
       writeBytes(Export.FieldName);
 
-      write8(Export.Kind);
+      encodeSLEB128(Export.Kind, getStream());
 
       encodeULEB128(Export.Index, getStream());
     }
@@ -1007,7 +1011,7 @@
   if (!CodeRelocations.empty()) {
     startSection(Section, wasm::WASM_SEC_CUSTOM, "reloc.CODE");
 
-    write8(wasm::WASM_SEC_CODE);
+    encodeULEB128(wasm::WASM_SEC_CODE, getStream());
 
     encodeULEB128(CodeRelocations.size(), getStream());
 
@@ -1020,7 +1024,7 @@
   if (!DataRelocations.empty()) {
     startSection(Section, wasm::WASM_SEC_CUSTOM, "reloc.DATA");
 
-    write8(wasm::WASM_SEC_DATA);
+    encodeULEB128(wasm::WASM_SEC_DATA, getStream());
 
     encodeULEB128(DataRelocations.size(), getStream());