[X86] Cast atomic vectors in IR to support floats

This commit casts floats to ints in an atomic load during AtomicExpand to support
floating point types. It also is required to support 128 bit vectors in SSE/AVX.

Author: jofrn

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -32136,6 +32136,13 @@ X86TargetLowering::shouldExpandAtomicRMWInIR(AtomicRMWInst *AI) const {
   }
 }
 
+TargetLowering::AtomicExpansionKind
+X86TargetLowering::shouldCastAtomicLoadInIR(LoadInst *LI) const {
+  if (LI->getType()->getScalarType()->isFloatingPointTy())
+    return AtomicExpansionKind::CastToInteger;
+  return AtomicExpansionKind::None;
+}
+
 LoadInst *
 X86TargetLowering::lowerIdempotentRMWIntoFencedLoad(AtomicRMWInst *AI) const {
   unsigned NativeWidth = Subtarget.is64Bit() ? 64 : 32;

llvm/lib/Target/X86/X86ISelLowering.h

@@ -1841,6 +1841,8 @@ namespace llvm {
     shouldExpandAtomicRMWInIR(AtomicRMWInst *AI) const override;
     TargetLoweringBase::AtomicExpansionKind
     shouldExpandLogicAtomicRMWInIR(AtomicRMWInst *AI) const;
+    TargetLoweringBase::AtomicExpansionKind
+    shouldCastAtomicLoadInIR(LoadInst *LI) const override;
     void emitBitTestAtomicRMWIntrinsic(AtomicRMWInst *AI) const override;
     void emitCmpArithAtomicRMWIntrinsic(AtomicRMWInst *AI) const override;