[OpaquePtr] Create new bitcode encoding for atomicrmw

Since the opaque pointer type won't contain the pointee type, we need to
separately encode the value type for an atomicrmw.

Emit this new code for atomicrmw.

Handle this new code and the old one in the bitcode reader.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D103123

llvm/include/llvm/Bitcode/LLVMBitCodes.h

@@ -547,15 +547,15 @@ enum FunctionCodes {
 
   FUNC_CODE_INST_CALL = 34, // CALL:    [attr, cc, fnty, fnid, args...]
 
-  FUNC_CODE_DEBUG_LOC = 35,        // DEBUG_LOC:  [Line,Col,ScopeVal, IAVal]
-  FUNC_CODE_INST_FENCE = 36,       // FENCE: [ordering, synchscope]
-  FUNC_CODE_INST_CMPXCHG_OLD = 37, // CMPXCHG: [ptrty, ptr, cmp, val, vol,
-                                   //            ordering, synchscope,
-                                   //            failure_ordering?, weak?]
-  FUNC_CODE_INST_ATOMICRMW = 38,   // ATOMICRMW: [ptrty,ptr,val, operation,
-                                   //             align, vol,
-                                   //             ordering, synchscope]
-  FUNC_CODE_INST_RESUME = 39,      // RESUME:     [opval]
+  FUNC_CODE_DEBUG_LOC = 35,          // DEBUG_LOC:  [Line,Col,ScopeVal, IAVal]
+  FUNC_CODE_INST_FENCE = 36,         // FENCE: [ordering, synchscope]
+  FUNC_CODE_INST_CMPXCHG_OLD = 37,   // CMPXCHG: [ptrty, ptr, cmp, val, vol,
+                                     //            ordering, synchscope,
+                                     //            failure_ordering?, weak?]
+  FUNC_CODE_INST_ATOMICRMW_OLD = 38, // ATOMICRMW: [ptrty,ptr,val, operation,
+                                     //             align, vol,
+                                     //             ordering, synchscope]
+  FUNC_CODE_INST_RESUME = 39,        // RESUME:     [opval]
   FUNC_CODE_INST_LANDINGPAD_OLD =
       40,                         // LANDINGPAD: [ty,val,val,num,id0,val0...]
   FUNC_CODE_INST_LOADATOMIC = 41, // LOAD: [opty, op, align, vol,
@@ -582,6 +582,9 @@ enum FunctionCodes {
   FUNC_CODE_INST_CALLBR = 57,    // CALLBR:     [attr, cc, norm, transfs,
                                  //              fnty, fnid, args...]
   FUNC_CODE_INST_FREEZE = 58,    // FREEZE: [opty, opval]
+  FUNC_CODE_INST_ATOMICRMW = 59, // ATOMICRMW: [ptrty, ptr, valty, val,
+                                 //             operation, align, vol,
+                                 //             ordering, synchscope]
 };
 
 enum UseListCodes {

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -5232,8 +5232,10 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
       InstructionList.push_back(I);
       break;
     }
+    case bitc::FUNC_CODE_INST_ATOMICRMW_OLD:
     case bitc::FUNC_CODE_INST_ATOMICRMW: {
-      // ATOMICRMW:[ptrty, ptr, val, op, vol, ordering, ssid, align?]
+      // ATOMICRMW_OLD: [ptrty, ptr, val, op, vol, ordering, ssid, align?]
+      // ATOMICRMW: [ptrty, ptr, valty, val, op, vol, ordering, ssid, align?]
       const size_t NumRecords = Record.size();
       unsigned OpNum = 0;
 
@@ -5245,9 +5247,14 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
         return error("Invalid record");
 
       Value *Val = nullptr;
-      if (popValue(Record, OpNum, NextValueNo,
-                   getPointerElementFlatType(FullTy), Val))
-        return error("Invalid record");
+      if (BitCode == bitc::FUNC_CODE_INST_ATOMICRMW_OLD) {
+        if (popValue(Record, OpNum, NextValueNo,
+                     getPointerElementFlatType(FullTy), Val))
+          return error("Invalid record");
+      } else {
+        if (getValueTypePair(Record, OpNum, NextValueNo, Val))
+          return error("Invalid record");
+      }
 
       if (!(NumRecords == (OpNum + 4) || NumRecords == (OpNum + 5)))
         return error("Invalid record");

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -3103,7 +3103,7 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
   case Instruction::AtomicRMW:
     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
-    pushValue(I.getOperand(1), InstID, Vals);        // val.
+    pushValueAndType(I.getOperand(1), InstID, Vals); // valty + val
     Vals.push_back(
         getEncodedRMWOperation(cast<AtomicRMWInst>(I).getOperation()));
     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());

llvm/test/Bitcode/atomicrmw-upgrade.ll

@@ -0,0 +1,12 @@
+; RUN: llvm-dis < %s.bc | FileCheck %s
+; RUN: verify-uselistorder < %s.bc
+
+; atomicrmw-upgrade.ll.bc was produced by running a version of llvm-as from just
+; before the IR change on this file.
+
+; CHECK: @atomicrmw
+; CHECK:   %b = atomicrmw add i32* %a, i32 %i acquire
+define void @atomicrmw(i32* %a, i32 %i) {
+    %b = atomicrmw add i32* %a, i32 %i acquire
+    ret void
+}