Revert r351778: IR: Add fp operations to atomicrmw

This broke the RISCV build, and even with that fixed, one of the RISCV
tests behaves surprisingly differently with asserts than without,
leaving there no clear test pattern to use. Generally it seems bad for
hte IR to differ substantially due to asserts (as in, an alloca is used
with asserts that isn't needed without!) and nothing I did simply would
fix it so I'm reverting back to green.

This also required reverting the RISCV build fix in r351782.

llvm-svn: 351796

1 files changed, 0 insertions, 6 deletions

diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index b9e23df428e..8a32d957ec5 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -1720,12 +1720,6 @@ Instruction *RISCVTargetLowering::emitTrailingFence(IRBuilder<> &Builder,
 
 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
-  // brekaing the forward-progress guarantee.
-  if (AI->isFloatingPointOperation())
-    return AtomicExpansionKind::CmpXChg;
-
   unsigned Size = AI->getType()->getPrimitiveSizeInBits();
   if (Size == 8 || Size == 16)
     return AtomicExpansionKind::MaskedIntrinsic;