[llvm] r253344 - [AArch64] Promote f16 SELECT_CC CC operands when op is legal.

[Ahmed Bougacha via llvm-commits]

Author: ab
Date: Tue Nov 17 10:45:40 2015
New Revision: 253344

URL: http://llvm.org/viewvc/llvm-project?rev=253344&view=rev
Log:
[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.

Modified:
    llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp
    llvm/trunk/test/CodeGen/AArch64/f16-instructions.ll

Modified: llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp?rev=253344&r1=253343&r2=253344&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp Tue Nov 17 10:45:40 2015
@@ -3887,7 +3887,13 @@ SDValue AArch64TargetLowering::LowerSELE
     }
   }
 
-  // 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));

Modified: llvm/trunk/test/CodeGen/AArch64/f16-instructions.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/f16-instructions.ll?rev=253344&r1=253343&r2=253344&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/f16-instructions.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/f16-instructions.ll Tue Nov 17 10:45:40 2015
@@ -143,6 +143,33 @@ define half @test_select_cc(half %a, hal
   ret half %r
 }
 
+; CHECK-LABEL: test_select_cc_f32_f16:
+; CHECK-DAG:   fcvt s2, h2
+; CHECK-DAG:   fcvt s3, h3
+; CHECK-NEXT:  fcmp s2, s3
+; CHECK-NEXT:  fcsel s0, s0, s1, ne
+; CHECK-NEXT:  ret
+define float @test_select_cc_f32_f16(float %a, float %b, half %c, half %d) #0 {
+  %cc = fcmp une half %c, %d
+  %r = select i1 %cc, float %a, float %b
+  ret float %r
+}
+
+; CHECK-LABEL: test_select_cc_f16_f32:
+; CHECK-DAG:  fcvt s0, h0
+; CHECK-DAG:  fcvt s1, h1
+; CHECK-DAG:  fcmp s2, s3
+; CHECK-DAG:  cset w8, ne
+; CHECK-NEXT: cmp w8, #0
+; CHECK-NEXT: fcsel s0, s0, s1, ne
+; CHECK-NEXT: fcvt h0, s0
+; CHECK-NEXT: ret
+define half @test_select_cc_f16_f32(half %a, half %b, float %c, float %d) #0 {
+  %cc = fcmp une float %c, %d
+  %r = select i1 %cc, half %a, half %b
+  ret half %r
+}
+
 ; CHECK-LABEL: test_fcmp_une:
 ; CHECK-NEXT: fcvt s1, h1
 ; CHECK-NEXT: fcvt s0, h0