Encode alignment attribute for `cmpxchg`

This is a follow up patch to D83136 adding the align attribute to `cmpxchg`.
See also D83465 for `atomicrmw`.

Differential Revision: https://reviews.llvm.org/D87443

1 files changed, 21 insertions, 8 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 365cf5f..4a77f8c 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -5085,7 +5085,7 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
     }
     case bitc::FUNC_CODE_INST_CMPXCHG: {
       // CMPXCHG: [ptrty, ptr, cmp, val, vol, success_ordering, synchscope,
-      // failure_ordering, weak]
+      // failure_ordering, weak, align?]
       const size_t NumRecords = Record.size();
       unsigned OpNum = 0;
       Value *Ptr = nullptr;
@@ -5100,10 +5100,14 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
         return error("Invalid record");
 
       Value *Val = nullptr;
-      if (popValue(Record, OpNum, NextValueNo, Cmp->getType(), Val) ||
-          NumRecords < OpNum + 3 || NumRecords > OpNum + 5)
+      if (popValue(Record, OpNum, NextValueNo, Cmp->getType(), Val))
+        return error("Invalid record");
+
+      if (NumRecords < OpNum + 3 || NumRecords > OpNum + 6)
         return error("Invalid record");
 
+      const bool IsVol = Record[OpNum];
+
       const AtomicOrdering SuccessOrdering =
           getDecodedOrdering(Record[OpNum + 1]);
       if (SuccessOrdering == AtomicOrdering::NotAtomic ||
@@ -5118,14 +5122,23 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
       const AtomicOrdering FailureOrdering =
           getDecodedOrdering(Record[OpNum + 3]);
 
-      const Align Alignment(
-          TheModule->getDataLayout().getTypeStoreSize(Cmp->getType()));
+      const bool IsWeak = Record[OpNum + 4];
+
+      MaybeAlign Alignment;
 
-      I = new AtomicCmpXchgInst(Ptr, Cmp, Val, Alignment, SuccessOrdering,
+      if (NumRecords == (OpNum + 6)) {
+        if (Error Err = parseAlignmentValue(Record[OpNum + 5], Alignment))
+          return Err;
+      }
+      if (!Alignment)
+        Alignment =
+            Align(TheModule->getDataLayout().getTypeStoreSize(Cmp->getType()));
+
+      I = new AtomicCmpXchgInst(Ptr, Cmp, Val, *Alignment, SuccessOrdering,
                                 FailureOrdering, SSID);
       FullTy = StructType::get(Context, {FullTy, Type::getInt1Ty(Context)});
-      cast<AtomicCmpXchgInst>(I)->setVolatile(Record[OpNum]);
-      cast<AtomicCmpXchgInst>(I)->setWeak(Record[OpNum + 4]);
+      cast<AtomicCmpXchgInst>(I)->setVolatile(IsVol);
+      cast<AtomicCmpXchgInst>(I)->setWeak(IsWeak);
 
       InstructionList.push_back(I);
       break;