[X86] Manage atomic load of fp -> int promotion in DAG

When lowering atomic <1 x T> vector types with floats, selection can fail since
this pattern is unsupported. To support this, floats can be casted to
an integer type of the same size.

commit-id:f9d761c5

Author: jofrn

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -2595,6 +2595,10 @@ X86TargetLowering::X86TargetLowering(const X86TargetMachine &TM,
         setOperationAction(Op, MVT::f32, Promote);
   }
 
+  setOperationPromotedToType(ISD::ATOMIC_LOAD, MVT::f16, MVT::i16);
+  setOperationPromotedToType(ISD::ATOMIC_LOAD, MVT::f32, MVT::i32);
+  setOperationPromotedToType(ISD::ATOMIC_LOAD, MVT::f64, MVT::i64);
+
   // We have target-specific dag combine patterns for the following nodes:
   setTargetDAGCombine({ISD::VECTOR_SHUFFLE,
                        ISD::SCALAR_TO_VECTOR,

llvm/test/CodeGen/X86/atomic-load-store.ll

@@ -136,3 +136,31 @@ define <1 x ptr> @atomic_vec1_ptr_align8(ptr %x) nounwind {
   %ret = load atomic <1 x ptr>, ptr %x acquire, align 8
   ret <1 x ptr> %ret
 }
+
+define <1 x half> @atomic_vec1_half(ptr %x) {
+; CHECK3-LABEL: atomic_vec1_half:
+; CHECK3:       ## %bb.0:
+; CHECK3-NEXT:    movzwl (%rdi), %eax
+; CHECK3-NEXT:    pinsrw $0, %eax, %xmm0
+; CHECK3-NEXT:    retq
+;
+; CHECK0-LABEL: atomic_vec1_half:
+; CHECK0:       ## %bb.0:
+; CHECK0-NEXT:    movw (%rdi), %cx
+; CHECK0-NEXT:    ## implicit-def: $eax
+; CHECK0-NEXT:    movw %cx, %ax
+; CHECK0-NEXT:    ## implicit-def: $xmm0
+; CHECK0-NEXT:    pinsrw $0, %eax, %xmm0
+; CHECK0-NEXT:    retq
+  %ret = load atomic <1 x half>, ptr %x acquire, align 4
+  ret <1 x half> %ret
+}
+
+define <1 x float> @atomic_vec1_float(ptr %x) {
+; CHECK-LABEL: atomic_vec1_float:
+; CHECK:       ## %bb.0:
+; CHECK-NEXT:    movss {{.*#+}} xmm0 = mem[0],zero,zero,zero
+; CHECK-NEXT:    retq
+  %ret = load atomic <1 x float>, ptr %x acquire, align 4
+  ret <1 x float> %ret
+}