PPC: Add a FIXME regarding the non-working fma+fneg Altivec pattern

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178658 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/PowerPC/PPCInstrAltivec.td b/lib/Target/PowerPC/PPCInstrAltivec.td
index 572424e3be14f16b9e7131be773faba15bba9846..a5ba4c8aebef7f9ab9a7770156fdb10e65c4d2b4 100644 (file)
--- a/lib/Target/PowerPC/PPCInstrAltivec.td
+++ b/lib/Target/PowerPC/PPCInstrAltivec.td
@@ -318,6 +318,8 @@ def VMADDFP : VAForm_1<46, (outs VRRC:$vD), (ins VRRC:$vA, VRRC:$vC, VRRC:$vB),
                        "vmaddfp $vD, $vA, $vC, $vB", VecFP,
                        [(set v4f32:$vD,
                         (fma v4f32:$vA, v4f32:$vC, v4f32:$vB))]>;
+
+// FIXME: The fma+fneg pattern won't match because fneg is not legal.
 def VNMSUBFP: VAForm_1<47, (outs VRRC:$vD), (ins VRRC:$vA, VRRC:$vC, VRRC:$vB),
                        "vnmsubfp $vD, $vA, $vC, $vB", VecFP,
                        [(set v4f32:$vD, (fneg (fma v4f32:$vA, v4f32:$vC,