Remove generating STRUCT_ANON records in PNaCl bitcode files.

Don't generate types for elided cast instructions, since they
are never put into the bitcode file. In addition, do not generate
a type id for the types of global variables, because they are never
needed. Don't allow and STRUCT records in bitcode files
when PNaClVersion==2.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=3648
R=mseaborn@chromium.org

Review URL: https://codereview.chromium.org/23431008

6 files changed, 73 insertions, 44 deletions

diff --git a/include/llvm/Bitcode/NaCl/NaClLLVMBitCodes.h b/include/llvm/Bitcode/NaCl/NaClLLVMBitCodes.h
index b9c358f271..50182667b5 100644
--- a/include/llvm/Bitcode/NaCl/NaClLLVMBitCodes.h
+++ b/include/llvm/Bitcode/NaCl/NaClLLVMBitCodes.h
@@ -105,7 +105,10 @@ namespace naclbitc {
 
     TYPE_CODE_X86_MMX = 17,     // Not used in PNaCl.
 
-    TYPE_CODE_STRUCT_ANON = 18, // STRUCT_ANON: [ispacked, eltty x N]
+    TYPE_CODE_STRUCT_ANON = 18, // PNaCl version 1 (early versions only)
+                                // STRUCT_ANON: [ispacked, eltty x N]
+                                // Not used in PNaCl otherwise (i.e.
+                                // PNaCl versions 1+).
     TYPE_CODE_STRUCT_NAME = 19, // Not used in PNaCl.
     TYPE_CODE_STRUCT_NAMED = 20,// Not used in PNaCl.
 
diff --git a/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp b/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp
index 9e8c398172..3bd1e2f783 100644
--- a/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp
+++ b/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp
@@ -489,6 +489,10 @@ bool NaClBitcodeReader::ParseTypeTableBody() {
       break;
     }
     case naclbitc::TYPE_CODE_STRUCT_ANON: {  // STRUCT: [ispacked, eltty x N]
+      // Deprecated. Only exists in early PNaCl version 1 bitcode files.
+      // TODO(kschimpf) Remove this as soon as is feasible.
+      if (GetPNaClVersion() >= 2)
+        return Error("Struct types not supported in PNaCl bitcode");
       if (Record.size() < 1)
         return Error("Invalid STRUCT type record");
       SmallVector<Type*, 8> EltTys;
diff --git a/lib/Bitcode/NaCl/Writer/NaClBitcodeWriter.cpp b/lib/Bitcode/NaCl/Writer/NaClBitcodeWriter.cpp
index 41a2501266..80bf60f2ce 100644
--- a/lib/Bitcode/NaCl/Writer/NaClBitcodeWriter.cpp
+++ b/lib/Bitcode/NaCl/Writer/NaClBitcodeWriter.cpp
@@ -94,7 +94,6 @@ enum {
   // TYPE_BLOCK_ID_NEW abbrev id's.
   TYPE_POINTER_ABBREV = naclbitc::FIRST_APPLICATION_ABBREV,
   TYPE_FUNCTION_ABBREV,
-  TYPE_STRUCT_ANON_ABBREV,
   TYPE_ARRAY_ABBREV,
   TYPE_MAX_ABBREV = TYPE_ARRAY_ABBREV
 };
@@ -201,15 +200,6 @@ static void WriteTypeTable(const NaClValueEnumerator &VE,
   if (TYPE_FUNCTION_ABBREV != Stream.EmitAbbrev(Abbv))
     llvm_unreachable("Unexpected abbrev ordering!");
 
-  // Abbrev for TYPE_CODE_STRUCT_ANON.
-  Abbv = new NaClBitCodeAbbrev();
-  Abbv->Add(NaClBitCodeAbbrevOp(naclbitc::TYPE_CODE_STRUCT_ANON));
-  Abbv->Add(NaClBitCodeAbbrevOp(NaClBitCodeAbbrevOp::Fixed, 1));  // ispacked
-  Abbv->Add(NaClBitCodeAbbrevOp(NaClBitCodeAbbrevOp::Array));
-  Abbv->Add(NaClBitCodeAbbrevOp(NaClBitCodeAbbrevOp::Fixed, NumBits));
-  if (TYPE_STRUCT_ANON_ABBREV != Stream.EmitAbbrev(Abbv))
-    llvm_unreachable("Unexpected abbrev ordering!");
-
   // Abbrev for TYPE_CODE_ARRAY.
   Abbv = new NaClBitCodeAbbrev();
   Abbv->Add(NaClBitCodeAbbrevOp(naclbitc::TYPE_CODE_ARRAY));
@@ -261,23 +251,8 @@ static void WriteTypeTable(const NaClValueEnumerator &VE,
       AbbrevToUse = TYPE_FUNCTION_ABBREV;
       break;
     }
-    case Type::StructTyID: {
-      StructType *ST = cast<StructType>(T);
-      // STRUCT: [ispacked, eltty x N]
-      TypeVals.push_back(ST->isPacked());
-      // Output all of the element types.
-      for (StructType::element_iterator I = ST->element_begin(),
-           E = ST->element_end(); I != E; ++I)
-        TypeVals.push_back(VE.getTypeID(*I));
-
-      if (ST->isLiteral()) {
-        Code = naclbitc::TYPE_CODE_STRUCT_ANON;
-        AbbrevToUse = TYPE_STRUCT_ANON_ABBREV;
-      } else {
-        report_fatal_error("Non-anon structs not supported in PNaCl bitcode");
-      }
-      break;
-    }
+    case Type::StructTyID:
+      report_fatal_error("Struct types are not supported in PNaCl bitcode");
     case Type::ArrayTyID: {
       ArrayType *AT = cast<ArrayType>(T);
       // ARRAY: [numelts, eltty]
diff --git a/lib/Bitcode/NaCl/Writer/NaClValueEnumerator.cpp b/lib/Bitcode/NaCl/Writer/NaClValueEnumerator.cpp
index 8cfdf13240..8e35f59909 100644
--- a/lib/Bitcode/NaCl/Writer/NaClValueEnumerator.cpp
+++ b/lib/Bitcode/NaCl/Writer/NaClValueEnumerator.cpp
@@ -89,6 +89,10 @@ NaClValueEnumerator::NaClValueEnumerator(const Module *M, uint32_t PNaClVersion)
 
     for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
       for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E;++I){
+        // Don't generate types for elided pointer casts!
+        if (I == ElideCasts(I))
+          continue;
+
         for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
              OI != E; ++OI) {
           EnumerateOperandType(*OI);
@@ -356,6 +360,11 @@ void NaClValueEnumerator::EnumerateType(Type *Ty, bool InsideOptimizeTypes) {
 // Enumerate the types for the specified value.  If the value is a constant,
 // walk through it, enumerating the types of the constant.
 void NaClValueEnumerator::EnumerateOperandType(const Value *V) {
+  // Note: We intentionally don't create a type id for global variables,
+  // since the type is automatically generated by the reader before any
+  // use of the global variable.
+  if (isa<GlobalVariable>(V)) return;
+
   EnumerateType(V->getType());
 
   if (const Constant *C = dyn_cast<Constant>(V)) {
diff --git a/test/NaCl/Bitcode/no-structs.ll b/test/NaCl/Bitcode/no-structs.ll
new file mode 100644
index 0000000000..1f9b1279fe
--- /dev/null
+++ b/test/NaCl/Bitcode/no-structs.ll
@@ -0,0 +1,38 @@
+; Tests that even though global variables can define structured types,
+; they types are not put into the bitcode file.
+
+; RUN: llvm-as < %s | pnacl-freeze --pnacl-version=1 \
+; RUN:              | pnacl-bcanalyzer -dump-records \
+; RUN:              | FileCheck %s 
+
+; RUN: llvm-as < %s | pnacl-freeze --pnacl-version=2 \
+; RUN:              | pnacl-bcanalyzer -dump-records \
+; RUN:              | FileCheck %s 
+
+declare void @func()
+
+@compound = internal global <{ [4 x i8], i32 }>
+    <{ [4 x i8] c"home", i32 ptrtoint (void ()* @func to i32) }>
+
+define void @CheckBitcastGlobal() {
+  %1 = bitcast <{ [4 x i8], i32}>* @compound to i32*
+  %2 = load i32* %1, align 4
+  ret void
+}
+
+define void @CheckPtrToIntGlobal() {
+  %1 = ptrtoint <{ [4 x i8], i32 }>* @compound to i32
+  %2 = add i32 %1, 0
+  ret void
+}
+
+; Note that neither pnacl-version defines a struct type.
+
+; CHECK:      <TYPE_BLOCK_ID>
+; CHECK-NEXT:   <NUMENTRY op0=5/>
+; CHECK-NEXT:   <INTEGER op0=32/>
+; CHECK-NEXT:   <VOID/>
+; CHECK-NEXT:   <FUNCTION op0=0 op1=1/>
+; CHECK-NEXT:   <POINTER op0=2 op1=0/>
+; CHECK-NEXT:   <POINTER op0=0 op1=0/>
+; CHECK-NEXT: </TYPE_BLOCK_ID>
diff --git a/test/NaCl/Bitcode/ptrtoint-elide.ll b/test/NaCl/Bitcode/ptrtoint-elide.ll
index eba451c289..3ef7909fe7 100644
--- a/test/NaCl/Bitcode/ptrtoint-elide.ll
+++ b/test/NaCl/Bitcode/ptrtoint-elide.ll
@@ -638,14 +638,14 @@ define void @TestCasts() {
 ; PF1-NEXT:     <INST_CAST op0=1 op1=0 op2=9/>
 ; PF1-NEXT:     <INST_CAST op0=6 op1=2 op2=0/>
 ; PF1-NEXT:     <INST_CAST op0=2 op1=2 op2=0/>
-; PF1-NEXT:     <INST_CAST op0=8 op1=13 op2=1/>
-; PF1-NEXT:     <INST_CAST op0=4 op1=13 op2=1/>
-; PF1-NEXT:     <INST_CAST op0=9 op1=13 op2=2/>
-; PF1-NEXT:     <INST_CAST op0=6 op1=13 op2=2/>
-; PF1-NEXT:     <INST_CAST op0=9 op1=14 op2=5/>
-; PF1-NEXT:     <INST_CAST op0=8 op1=14 op2=5/>
-; PF1-NEXT:     <INST_CAST op0=13 op1=14 op2=6/>
-; PF1-NEXT:     <INST_CAST op0=10 op1=14 op2=6/>
+; PF1-NEXT:     <INST_CAST op0=8 op1=11 op2=1/>
+; PF1-NEXT:     <INST_CAST op0=4 op1=11 op2=1/>
+; PF1-NEXT:     <INST_CAST op0=9 op1=11 op2=2/>
+; PF1-NEXT:     <INST_CAST op0=6 op1=11 op2=2/>
+; PF1-NEXT:     <INST_CAST op0=9 op1=12 op2=5/>
+; PF1-NEXT:     <INST_CAST op0=8 op1=12 op2=5/>
+; PF1-NEXT:     <INST_CAST op0=13 op1=12 op2=6/>
+; PF1-NEXT:     <INST_CAST op0=10 op1=12 op2=6/>
 ; PF1-NEXT:     <INST_RET/>
 ; PF1-NEXT:   </FUNCTION_BLOCK>
 
@@ -670,14 +670,14 @@ define void @TestCasts() {
 ; PF2-NEXT:     <INST_ALLOCA op0=2 op1=4/>
 ; PF2-NEXT:     <INST_CAST op0=5 op1=2 op2=0/>
 ; PF2-NEXT:     <INST_CAST op0=2 op1=2 op2=0/>
-; PF2-NEXT:     <INST_CAST op0=7 op1=13 op2=1/>
-; PF2-NEXT:     <INST_CAST op0=4 op1=13 op2=1/>
-; PF2-NEXT:     <INST_CAST op0=8 op1=13 op2=2/>
-; PF2-NEXT:     <INST_CAST op0=6 op1=13 op2=2/>
-; PF2-NEXT:     <INST_CAST op0=8 op1=14 op2=5/>
-; PF2-NEXT:     <INST_CAST op0=8 op1=14 op2=5/>
-; PF2-NEXT:     <INST_CAST op0=12 op1=14 op2=6/>
-; PF2-NEXT:     <INST_CAST op0=10 op1=14 op2=6/>
+; PF2-NEXT:     <INST_CAST op0=7 op1=11 op2=1/>
+; PF2-NEXT:     <INST_CAST op0=4 op1=11 op2=1/>
+; PF2-NEXT:     <INST_CAST op0=8 op1=11 op2=2/>
+; PF2-NEXT:     <INST_CAST op0=6 op1=11 op2=2/>
+; PF2-NEXT:     <INST_CAST op0=8 op1=12 op2=5/>
+; PF2-NEXT:     <INST_CAST op0=8 op1=12 op2=5/>
+; PF2-NEXT:     <INST_CAST op0=12 op1=12 op2=6/>
+; PF2-NEXT:     <INST_CAST op0=10 op1=12 op2=6/>
 ; PF2-NEXT:     <INST_RET/>
 ; PF2-NEXT:   </FUNCTION_BLOCK>