Use PNaCl intrinsics based approach for handling atomic cmpxchg.

Author: juj

lib/Target/JSBackend/CallHandlers.h

@@ -314,16 +314,21 @@ DEF_CALL_HANDLER(llvm_nacl_atomic_store_i32, {
   return "HEAP32[" + getValueAsStr(CI->getOperand(0)) + ">>2]=" + getValueAsStr(CI->getOperand(1));
 })
 
-#define CMPXCHG_HANDLER(name) \
+#define CMPXCHG_HANDLER(name, HeapName) \
 DEF_CALL_HANDLER(name, { \
   const Value *P = CI->getOperand(0); \
-  return getLoad(CI, P, CI->getType(), 0) + ';' + \
-         "if ((" + getCast(getJSName(CI), CI->getType()) + ") == " + getValueAsCastParenStr(CI->getOperand(1)) + ") " + \
-            getStore(CI, P, CI->getType(), getValueAsStr(CI->getOperand(2)), 0); \
-})
-CMPXCHG_HANDLER(llvm_nacl_atomic_cmpxchg_i8);
-CMPXCHG_HANDLER(llvm_nacl_atomic_cmpxchg_i16);
-CMPXCHG_HANDLER(llvm_nacl_atomic_cmpxchg_i32);
+  if (EnablePthreads) { \
+    return getAssign(CI) + "Atomics_compareExchange(" HeapName ", " + getAddressAsString(CI->getOperand(0), 2) + ", " + getValueAsStr(CI->getOperand(1)) + ", " + getValueAsStr(CI->getOperand(2)) + ")"; \
+  } else { \
+    return getLoad(CI, P, CI->getType(), 0) + ';' + \
+             "if ((" + getCast(getJSName(CI), CI->getType()) + ") == " + getValueAsCastParenStr(CI->getOperand(1)) + ") " + \
+                getStore(CI, P, CI->getType(), getValueAsStr(CI->getOperand(2)), 0); \
+  } \
+})
+
+CMPXCHG_HANDLER(llvm_nacl_atomic_cmpxchg_i8, "HEAP8");
+CMPXCHG_HANDLER(llvm_nacl_atomic_cmpxchg_i16, "HEAP16");
+CMPXCHG_HANDLER(llvm_nacl_atomic_cmpxchg_i32, "HEAP32");
 
 #define UNROLL_LOOP_MAX 8
 #define WRITE_LOOP_MAX 128

lib/Target/JSBackend/JSBackend.cpp

@@ -2367,30 +2367,6 @@ void JSWriter::generateExpression(const User *I, raw_string_ostream& Code) {
                                     getValueAsStr(I->getOperand(2));
     break;
   }
-  case Instruction::ExtractValue: {
-    const ExtractValueInst *evi = cast<ExtractValueInst>(I);
-    std::string Assign = getAssign(evi);
-    Code << Assign << getValueAsStr(I->getOperand(0)) << "_" << evi->idx_begin()[0];
-    break;
-  }
-  case Instruction::AtomicCmpXchg: {
-    const AtomicCmpXchgInst *cxi = cast<AtomicCmpXchgInst>(I);
-    const Value *P = I->getOperand(0);
-    const char *HeapName;
-    std::string Index = getHeapNameAndIndex(P, &HeapName);
-    std::string Assign = getJSName(I);
-    UsedVars[Assign + "_0"] = I->getOperand(1)->getType();
-    UsedVars[Assign + "_1"] = Type::getInt1Ty(P->getContext());
-    if (EnablePthreads) {
-      Code << Assign << "_0 = Atomics_compareExchange(" << HeapName << ", " << Index << ", " << getValueAsStr(I->getOperand(1)) << ", " << getValueAsStr(I->getOperand(2)) << ");\n";
-      Code << Assign << "_1 = (" << Assign << "_0|0) == (" << getValueAsStr(I->getOperand(1)) << "|0)";
-    } else {
-      Code << Assign << "_0 = " << HeapName << "[" << Index << "];\n";
-      Code << Assign << "_1 = (" << Assign << "_0|0) == (" << getValueAsStr(I->getOperand(1)) << "|0); ";
-      Code << "if (" << Assign << "_1) " << getStore(cxi, P, I->getType(), getValueAsStr(I->getOperand(2)), 0);
-    }
-    break;
-  }
   case Instruction::AtomicRMW: {
     const AtomicRMWInst *rmwi = cast<AtomicRMWInst>(I);
     const Value *P = rmwi->getOperand(0);

lib/Transforms/NaCl/RewriteAtomics.cpp

@@ -379,7 +379,6 @@ void AtomicVisitor::visitAtomicRMWInst(AtomicRMWInst &I) {
 ///   %success = icmp eq %old, %val
 /// Note: weak is currently dropped if present, the cmpxchg is always strong.
 void AtomicVisitor::visitAtomicCmpXchgInst(AtomicCmpXchgInst &I) {
-  return; // XXX EMSCRIPTEN
   PointerHelper<AtomicCmpXchgInst> PH(*this, I);
   const NaCl::AtomicIntrinsics::AtomicIntrinsic *Intrinsic =
       findAtomicIntrinsic(I, Intrinsic::nacl_atomic_cmpxchg, PH.PET);