From b6a4640163855cc44a5af5f8a62face3a4cead3c Mon Sep 17 00:00:00 2001
From: Stepan Dyatkovskiy <stpworld@narod.ru>
Date: Tue, 8 May 2012 06:36:08 +0000
Subject: Ordinary patch for PR1255. Added new case-ranges orientated methods
 for adding/removing cases in SwitchInst. After this patch cases will
 internally representated as ConstantArray-s instead of ConstantInt,
 externally cases wrapped within the ConstantRangesSet object. Old methods of
 SwitchInst are also works well, but marked as deprecated. So on this stage we
 have no side effects except that I added support for case ranges in
 BitcodeReader/Writer, of course test for Bitcode is also added. Old "switch"
 format is also supported.

llvm-svn: 156374
---
 llvm/lib/Bitcode/Reader/BitcodeReader.cpp | 82 ++++++++++++++++++++++++++++---
 1 file changed, 75 insertions(+), 7 deletions(-)

(limited to 'llvm/lib/Bitcode/Reader/BitcodeReader.cpp')

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index e3990403bd7..a06a6f00f8b 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -28,6 +28,10 @@
 #include "llvm/OperandTraits.h"
 using namespace llvm;
 
+enum {
+  SWITCH_INST_MAGIC = 0x4B5 // May 2012 => 1205 => Hex
+};
+
 void BitcodeReader::materializeForwardReferencedFunctions() {
   while (!BlockAddrFwdRefs.empty()) {
     Function *F = BlockAddrFwdRefs.begin()->first;
@@ -977,6 +981,17 @@ bool BitcodeReader::ResolveGlobalAndAliasInits() {
   return false;
 }
 
+template <typename intty>
+APInt ReadWideAPInt(const intty *Vals, unsigned ActiveWords,
+                    unsigned TypeBits) {
+  SmallVector<uint64_t, 8> Words;
+  Words.resize(ActiveWords);
+  for (unsigned i = 0; i != ActiveWords; ++i)
+    Words[i] = DecodeSignRotatedValue(Vals[i]);
+  
+  return APInt(TypeBits, Words);
+}
+
 bool BitcodeReader::ParseConstants() {
   if (Stream.EnterSubBlock(bitc::CONSTANTS_BLOCK_ID))
     return Error("Malformed block record");
@@ -1033,13 +1048,11 @@ bool BitcodeReader::ParseConstants() {
         return Error("Invalid WIDE_INTEGER record");
 
       unsigned NumWords = Record.size();
-      SmallVector<uint64_t, 8> Words;
-      Words.resize(NumWords);
-      for (unsigned i = 0; i != NumWords; ++i)
-        Words[i] = DecodeSignRotatedValue(Record[i]);
-      V = ConstantInt::get(Context,
-                           APInt(cast<IntegerType>(CurTy)->getBitWidth(),
-                                 Words));
+      
+      APInt VInt = ReadWideAPInt(&Record[0], NumWords,
+          cast<IntegerType>(CurTy)->getBitWidth());
+      V = ConstantInt::get(Context, VInt);
+      
       break;
     }
     case bitc::CST_CODE_FLOAT: {    // FLOAT: [fpval]
@@ -2271,6 +2284,61 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
       break;
     }
     case bitc::FUNC_CODE_INST_SWITCH: { // SWITCH: [opty, op0, op1, ...]
+      // Check magic 
+      if ((Record[0] >> 16) == SWITCH_INST_MAGIC) {
+        // New SwitchInst format with case ranges.
+        
+        Type *OpTy = getTypeByID(Record[1]);
+        unsigned ValueBitWidth = cast<IntegerType>(OpTy)->getBitWidth();
+
+        Value *Cond = getFnValueByID(Record[2], OpTy);
+        BasicBlock *Default = getBasicBlock(Record[3]);
+        if (OpTy == 0 || Cond == 0 || Default == 0)
+          return Error("Invalid SWITCH record");
+
+        unsigned NumCases = Record[4];
+        
+        SwitchInst *SI = SwitchInst::Create(Cond, Default, NumCases);
+        
+        unsigned CurIdx = 5;
+        for (unsigned i = 0; i != NumCases; ++i) {
+          CRSBuilder CaseBuilder;
+          unsigned NumItems = Record[CurIdx++];
+          for (unsigned ci = 0; ci != NumItems; ++ci) {
+            bool isSingleNumber = Record[CurIdx++];
+            
+            APInt Low;
+            unsigned ActiveWords = 1;
+            if (ValueBitWidth > 64)
+              ActiveWords = Record[CurIdx++];
+            Low = ReadWideAPInt(&Record[CurIdx], ActiveWords, ValueBitWidth);
+            CurIdx += ActiveWords;
+            
+            if (!isSingleNumber) {
+              ActiveWords = 1;
+              if (ValueBitWidth > 64)
+                ActiveWords = Record[CurIdx++];
+              APInt High =
+                  ReadWideAPInt(&Record[CurIdx], ActiveWords, ValueBitWidth);
+              CaseBuilder.add(cast<ConstantInt>(ConstantInt::get(OpTy, Low)),
+                              cast<ConstantInt>(ConstantInt::get(OpTy, High)));
+              CurIdx += ActiveWords;
+            } else
+              CaseBuilder.add(cast<ConstantInt>(ConstantInt::get(OpTy, Low)));
+          }
+          BasicBlock *DestBB = getBasicBlock(Record[CurIdx++]);
+          ConstantRangesSet Case = CaseBuilder.getCase(); 
+          SI->addCase(Case, DestBB);
+        }
+        uint16_t Hash = SI->Hash();
+        if (Hash != (Record[0] & 0xFFFF))
+          return Error("Invalid SWITCH record");
+        I = SI;
+        break;
+      }
+      
+      // Old SwitchInst format without case ranges.
+      
       if (Record.size() < 3 || (Record.size() & 1) == 0)
         return Error("Invalid SWITCH record");
       Type *OpTy = getTypeByID(Record[0]);
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