[WebAssembly] Enable atomic expansion for unsupported atomicrmws
Summary:
Wasm does not have direct counterparts to some of LLVM IR's atomicrmw
instructions (min, max, umin, umax, and nand). This enables atomic
expansion using cmpxchg instruction within a loop for those atomicrmw
instructions.
Reviewers: dschuff
Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D49440
llvm-svn: 339084
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h
index 8e22f90..8b78b0e 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h
@@ -44,6 +44,7 @@
/// right decision when generating code for different targets.
const WebAssemblySubtarget *Subtarget;
+ AtomicExpansionKind shouldExpandAtomicRMWInIR(AtomicRMWInst *) const override;
FastISel *createFastISel(FunctionLoweringInfo &FuncInfo,
const TargetLibraryInfo *LibInfo) const override;
bool isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const override;