[AArch64] Promote f16 SELECT_CC CC operands when op is legal.

SELECT_CC has the nasty property of having operands with unrelated
types. So if you do something like:

  f32 = select_cc f16, f16, f32, f32, cc

You'd only look for the action for <select_cc, f32>, but never f16.
If the types are all legal, but the op isn't (as for f16 on AArch64,
or for f128 on x86_64/AArch64?), then you get into trouble.
For f128, we have softenSetCCOperands to handle this case.

Similarly, for f16, we can directly promote the CC operands.

llvm-svn: 253344

1 files changed, 7 insertions, 1 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index 14d2f6fb61a..26f03ef765d 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -3887,7 +3887,13 @@ SDValue AArch64TargetLowering::LowerSELECT_CC(ISD::CondCode CC, SDValue LHS,
     }
   }
 
-  // Handle integers first.
+  // Also handle f16, for which we need to do a f32 comparison.
+  if (LHS.getValueType() == MVT::f16) {
+    LHS = DAG.getNode(ISD::FP_EXTEND, dl, MVT::f32, LHS);
+    RHS = DAG.getNode(ISD::FP_EXTEND, dl, MVT::f32, RHS);
+  }
+
+  // Next, handle integers.
   if (LHS.getValueType().isInteger()) {
     assert((LHS.getValueType() == RHS.getValueType()) &&
            (LHS.getValueType() == MVT::i32 || LHS.getValueType() == MVT::i64));