From: David Blaikie <dblaikie@gmail.com>
Date: Mon, 27 Apr 2015 19:58:56 +0000 (+0000)
Subject: [opaque pointer type] encode the pointee type of global variables
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=d455682f390fc912e9001b909df59ec003f246f9

[opaque pointer type] encode the pointee type of global variables

Use a few extra bits in the const field (after widening it from a fixed
single bit) to stash the address space which is no longer provided by
the type (and an extra bit in there to specify that we're using that new
encoding).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235911 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index b6528cbbecc..1e9a8eb7fd1 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -2876,12 +2876,18 @@ std::error_code BitcodeReader::ParseModule(bool Resume,
       Type *Ty = getTypeByID(Record[0]);
       if (!Ty)
         return Error("Invalid record");
-      if (!Ty->isPointerTy())
-        return Error("Invalid type for value");
-      unsigned AddressSpace = cast<PointerType>(Ty)->getAddressSpace();
-      Ty = cast<PointerType>(Ty)->getElementType();
+      bool isConstant = Record[1] & 1;
+      bool explicitType = Record[1] & 2;
+      unsigned AddressSpace;
+      if (explicitType) {
+        AddressSpace = Record[1] >> 2;
+      } else {
+        if (!Ty->isPointerTy())
+          return Error("Invalid type for value");
+        AddressSpace = cast<PointerType>(Ty)->getAddressSpace();
+        Ty = cast<PointerType>(Ty)->getElementType();
+      }
 
-      bool isConstant = Record[1];
       uint64_t RawLinkage = Record[3];
       GlobalValue::LinkageTypes Linkage = getDecodedLinkage(RawLinkage);
       unsigned Alignment;
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index b8baabd22d8..840b75e496f 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -590,7 +590,7 @@ static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
   unsigned MaxGlobalType = 0;
   for (const GlobalValue &GV : M->globals()) {
     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
-    MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getType()));
+    MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
     if (GV.hasSection()) {
       // Give section names unique ID's.
       unsigned &Entry = SectionMap[GV.getSection()];
@@ -631,10 +631,12 @@ static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
                               Log2_32_Ceil(MaxGlobalType+1)));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5));      // Linkage.
-    if (MaxAlignment == 0)                                      // Alignment.
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
+                                                           //| explicitType << 1
+                                                           //| constant
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
+    if (MaxAlignment == 0)                                 // Alignment.
       Abbv->Add(BitCodeAbbrevOp(0));
     else {
       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
@@ -659,8 +661,8 @@ static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
     //             linkage, alignment, section, visibility, threadlocal,
     //             unnamed_addr, externally_initialized, dllstorageclass,
     //             comdat]
-    Vals.push_back(VE.getTypeID(GV.getType()));
-    Vals.push_back(GV.isConstant());
+    Vals.push_back(VE.getTypeID(GV.getValueType()));
+    Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
     Vals.push_back(GV.isDeclaration() ? 0 :
                    (VE.getValueID(GV.getInitializer()) + 1));
     Vals.push_back(getEncodedLinkage(GV));