[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.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
index aa3c0d0..b4bd161 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -157,6 +157,23 @@
setMaxAtomicSizeInBitsSupported(64);
}
+TargetLowering::AtomicExpansionKind
+WebAssemblyTargetLowering::shouldExpandAtomicRMWInIR(AtomicRMWInst *AI) const {
+ // We have wasm instructions for these
+ switch (AI->getOperation()) {
+ case AtomicRMWInst::Add:
+ case AtomicRMWInst::Sub:
+ case AtomicRMWInst::And:
+ case AtomicRMWInst::Or:
+ case AtomicRMWInst::Xor:
+ case AtomicRMWInst::Xchg:
+ return AtomicExpansionKind::None;
+ default:
+ break;
+ }
+ return AtomicExpansionKind::CmpXChg;
+}
+
FastISel *WebAssemblyTargetLowering::createFastISel(
FunctionLoweringInfo &FuncInfo, const TargetLibraryInfo *LibInfo) const {
return WebAssembly::createFastISel(FuncInfo, LibInfo);