Reapply "IR: Add fp operations to atomicrmw"
This reapplies commits r351778 and r351782 with
RISCV test fixes.
llvm-svn: 351850
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 95943f3..16591c4 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -1724,6 +1724,12 @@
TargetLowering::AtomicExpansionKind
RISCVTargetLowering::shouldExpandAtomicRMWInIR(AtomicRMWInst *AI) const {
+ // atomicrmw {fadd,fsub} must be expanded to use compare-exchange, as floating
+ // point operations can't be used in an lr/sc sequence without breaking the
+ // forward-progress guarantee.
+ if (AI->isFloatingPointOperation())
+ return AtomicExpansionKind::CmpXChg;
+
unsigned Size = AI->getType()->getPrimitiveSizeInBits();
if (Size == 8 || Size == 16)
return AtomicExpansionKind::MaskedIntrinsic;