[RISCV] Implement codegen for cmpxchg on RV32IA
Utilise a similar ('late') lowering strategy to D47882. The changes to
AtomicExpandPass allow this strategy to be utilised by other targets which
implement shouldExpandAtomicCmpXchgInIR.
All cmpxchg are lowered as 'strong' currently and failure ordering is ignored.
This is conservative but correct.
Differential Revision: https://reviews.llvm.org/D48131
llvm-svn: 347914
diff --git a/llvm/lib/CodeGen/AtomicExpandPass.cpp b/llvm/lib/CodeGen/AtomicExpandPass.cpp
index c1b9879..95581c0 100644
--- a/llvm/lib/CodeGen/AtomicExpandPass.cpp
+++ b/llvm/lib/CodeGen/AtomicExpandPass.cpp
@@ -91,6 +91,7 @@
AtomicRMWInst *widenPartwordAtomicRMW(AtomicRMWInst *AI);
void expandPartwordCmpXchg(AtomicCmpXchgInst *I);
void expandAtomicRMWToMaskedIntrinsic(AtomicRMWInst *AI);
+ void expandAtomicCmpXchgToMaskedIntrinsic(AtomicCmpXchgInst *CI);
AtomicCmpXchgInst *convertCmpXchgToIntegerType(AtomicCmpXchgInst *CI);
static Value *insertRMWCmpXchgLoop(
@@ -944,6 +945,35 @@
AI->eraseFromParent();
}
+void AtomicExpand::expandAtomicCmpXchgToMaskedIntrinsic(AtomicCmpXchgInst *CI) {
+ IRBuilder<> Builder(CI);
+
+ PartwordMaskValues PMV = createMaskInstrs(
+ Builder, CI, CI->getCompareOperand()->getType(), CI->getPointerOperand(),
+ TLI->getMinCmpXchgSizeInBits() / 8);
+
+ Value *CmpVal_Shifted = Builder.CreateShl(
+ Builder.CreateZExt(CI->getCompareOperand(), PMV.WordType), PMV.ShiftAmt,
+ "CmpVal_Shifted");
+ Value *NewVal_Shifted = Builder.CreateShl(
+ Builder.CreateZExt(CI->getNewValOperand(), PMV.WordType), PMV.ShiftAmt,
+ "NewVal_Shifted");
+ Value *OldVal = TLI->emitMaskedAtomicCmpXchgIntrinsic(
+ Builder, CI, PMV.AlignedAddr, CmpVal_Shifted, NewVal_Shifted, PMV.Mask,
+ CI->getSuccessOrdering());
+ Value *FinalOldVal = Builder.CreateTrunc(
+ Builder.CreateLShr(OldVal, PMV.ShiftAmt), PMV.ValueType);
+
+ Value *Res = UndefValue::get(CI->getType());
+ Res = Builder.CreateInsertValue(Res, FinalOldVal, 0);
+ Value *Success = Builder.CreateICmpEQ(
+ CmpVal_Shifted, Builder.CreateAnd(OldVal, PMV.Mask), "Success");
+ Res = Builder.CreateInsertValue(Res, Success, 1);
+
+ CI->replaceAllUsesWith(Res);
+ CI->eraseFromParent();
+}
+
Value *AtomicExpand::insertRMWLLSCLoop(
IRBuilder<> &Builder, Type *ResultTy, Value *Addr,
AtomicOrdering MemOpOrder,
@@ -1366,8 +1396,8 @@
return expandAtomicCmpXchg(CI);
}
case TargetLoweringBase::AtomicExpansionKind::MaskedIntrinsic:
- llvm_unreachable(
- "MaskedIntrinsic expansion of cmpxhg not yet implemented");
+ expandAtomicCmpXchgToMaskedIntrinsic(CI);
+ return true;
}
}