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.

llvm-svn: 136404

1 files changed, 25 insertions, 0 deletions

diff --git a/llvm/lib/VMCore/AsmWriter.cpp b/llvm/lib/VMCore/AsmWriter.cpp
index e6cd418c321..e3e2484def3 100644
--- a/llvm/lib/VMCore/AsmWriter.cpp
+++ b/llvm/lib/VMCore/AsmWriter.cpp
@@ -658,6 +658,23 @@ static const char *getPredicateText(unsigned predicate) {
   return pred;
 }
 
+static void writeAtomicRMWOperation(raw_ostream &Out,
+                                    AtomicRMWInst::BinOp Op) {
+  switch (Op) {
+  default: Out << " <unknown operation " << Op << ">"; break;
+  case AtomicRMWInst::Xchg: Out << " xchg"; break;
+  case AtomicRMWInst::Add:  Out << " add"; break;
+  case AtomicRMWInst::Sub:  Out << " sub"; break;
+  case AtomicRMWInst::And:  Out << " and"; break;
+  case AtomicRMWInst::Nand: Out << " nand"; break;
+  case AtomicRMWInst::Or:   Out << " or"; break;
+  case AtomicRMWInst::Xor:  Out << " xor"; break;
+  case AtomicRMWInst::Max:  Out << " max"; break;
+  case AtomicRMWInst::Min:  Out << " min"; break;
+  case AtomicRMWInst::UMax: Out << " umax"; break;
+  case AtomicRMWInst::UMin: Out << " umin"; break;
+  }
+}
 
 static void WriteOptimizationInfo(raw_ostream &Out, const User *U) {
   if (const OverflowingBinaryOperator *OBO =
@@ -1670,6 +1687,10 @@ void AssemblyWriter::printInstruction(const Instruction &I) {
   if (const CmpInst *CI = dyn_cast<CmpInst>(&I))
     Out << ' ' << getPredicateText(CI->getPredicate());
 
+  // Print out the atomicrmw operation
+  if (const AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(&I))
+    writeAtomicRMWOperation(Out, RMWI->getOperation());
+
   // Print out the type of the operands...
   const Value *Operand = I.getNumOperands() ? I.getOperand(0) : 0;
 
@@ -1936,6 +1957,10 @@ void AssemblyWriter::printInstruction(const Instruction &I) {
     Out << ", align " << cast<LoadInst>(I).getAlignment();
   } else if (isa<StoreInst>(I) && cast<StoreInst>(I).getAlignment()) {
     Out << ", align " << cast<StoreInst>(I).getAlignment();
+  } else if (const AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(&I)) {
+    writeAtomic(CXI->getOrdering(), CXI->getSynchScope());
+  } else if (const AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(&I)) {
+    writeAtomic(RMWI->getOrdering(), RMWI->getSynchScope());
   } else if (const FenceInst *FI = dyn_cast<FenceInst>(&I)) {
     writeAtomic(FI->getOrdering(), FI->getSynchScope());
   }