LangRef and basic memory-representation/reading/writing for 'cmpxchg' and

'atomicrmw' instructions, which allow representing all the current atomic
rmw intrinsics.

The allowed operands for these instructions are heavily restricted at the
moment; we can probably loosen it a bit, but supporting general
first-class types (where it makes sense) might get a bit complicated,
given how SelectionDAG works.

As an initial cut, these operations do not support specifying an alignment,
but it would be possible to add if we think it's useful. Specifying an
alignment lower than the natural alignment would be essentially
impossible to support on anything other than x86, but specifying a greater
alignment would be possible.  I can't think of any useful optimizations which
would use that information, but maybe someone else has ideas.

Optimizer/codegen support coming soon.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136404 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 59 insertions, 0 deletions

diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index bab33ed257..e0af683a24 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -131,6 +131,23 @@ static int GetDecodedBinaryOpcode(unsigned Val, Type *Ty) {
   }
 }
 
+static AtomicRMWInst::BinOp GetDecodedRMWOperation(unsigned Val) {
+  switch (Val) {
+  default: return AtomicRMWInst::BAD_BINOP;
+  case bitc::RMW_XCHG: return AtomicRMWInst::Xchg;
+  case bitc::RMW_ADD: return AtomicRMWInst::Add;
+  case bitc::RMW_SUB: return AtomicRMWInst::Sub;
+  case bitc::RMW_AND: return AtomicRMWInst::And;
+  case bitc::RMW_NAND: return AtomicRMWInst::Nand;
+  case bitc::RMW_OR: return AtomicRMWInst::Or;
+  case bitc::RMW_XOR: return AtomicRMWInst::Xor;
+  case bitc::RMW_MAX: return AtomicRMWInst::Max;
+  case bitc::RMW_MIN: return AtomicRMWInst::Min;
+  case bitc::RMW_UMAX: return AtomicRMWInst::UMax;
+  case bitc::RMW_UMIN: return AtomicRMWInst::UMin;
+  }
+}
+
 static AtomicOrdering GetDecodedOrdering(unsigned Val) {
   switch (Val) {
   case bitc::ORDERING_NOTATOMIC: return NotAtomic;
@@ -2595,6 +2612,48 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
       InstructionList.push_back(I);
       break;
     }
+    case bitc::FUNC_CODE_INST_CMPXCHG: {
+      // CMPXCHG:[ptrty, ptr, cmp, new, vol, ordering, synchscope]
+      unsigned OpNum = 0;
+      Value *Ptr, *Cmp, *New;
+      if (getValueTypePair(Record, OpNum, NextValueNo, Ptr) ||
+          getValue(Record, OpNum,
+                    cast<PointerType>(Ptr->getType())->getElementType(), Cmp) ||
+          getValue(Record, OpNum,
+                    cast<PointerType>(Ptr->getType())->getElementType(), New) ||
+          OpNum+3 != Record.size())
+        return Error("Invalid CMPXCHG record");
+      AtomicOrdering Ordering = GetDecodedOrdering(Record[OpNum+1]);
+      if (Ordering == NotAtomic)
+        return Error("Invalid CMPXCHG record");
+      SynchronizationScope SynchScope = GetDecodedSynchScope(Record[OpNum+2]);
+      I = new AtomicCmpXchgInst(Ptr, Cmp, New, Ordering, SynchScope);
+      cast<AtomicCmpXchgInst>(I)->setVolatile(Record[OpNum]);
+      InstructionList.push_back(I);
+      break;
+    }
+    case bitc::FUNC_CODE_INST_ATOMICRMW: {
+      // ATOMICRMW:[ptrty, ptr, val, op, vol, ordering, synchscope]
+      unsigned OpNum = 0;
+      Value *Ptr, *Val;
+      if (getValueTypePair(Record, OpNum, NextValueNo, Ptr) ||
+          getValue(Record, OpNum,
+                    cast<PointerType>(Ptr->getType())->getElementType(), Val) ||
+          OpNum+4 != Record.size())
+        return Error("Invalid ATOMICRMW record");
+      AtomicRMWInst::BinOp Operation = GetDecodedRMWOperation(Record[OpNum]);
+      if (Operation < AtomicRMWInst::FIRST_BINOP ||
+          Operation > AtomicRMWInst::LAST_BINOP)
+        return Error("Invalid ATOMICRMW record");
+      AtomicOrdering Ordering = GetDecodedOrdering(Record[OpNum+2]);
+      if (Ordering == NotAtomic)
+        return Error("Invalid ATOMICRMW record");
+      SynchronizationScope SynchScope = GetDecodedSynchScope(Record[OpNum+3]);
+      I = new AtomicRMWInst(Operation, Ptr, Val, Ordering, SynchScope);
+      cast<AtomicRMWInst>(I)->setVolatile(Record[OpNum+1]);
+      InstructionList.push_back(I);
+      break;
+    }
     case bitc::FUNC_CODE_INST_FENCE: { // FENCE:[ordering, synchscope]
       if (2 != Record.size())
         return Error("Invalid FENCE record");