[PowerPC] Expand v1i128 smin

[RolandF]

Summary

Fix a regression from D60160 where the cost model change enabled vector code to be generated with a v1i128 smin. There isn't an instruction for that but it was marked legal in PPCISelLowering.cpp.

[jsji]

LGTM with minor comments regarding testcase. Thanks.

llvm/test/CodeGen/PowerPC/vec-min-max.ll

241

This file was updated by script, so it is better to generate this using script as well.

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

if (Subtarget.hasAltivec()) {
     // will selectively turn on ones that can be effectively codegen'd.
     for (MVT VT : MVT::vector_valuetypes()) {
       // add/sub are legal for all supported vector VT's.
       setOperationAction(ISD::ADD, VT, Legal);
       setOperationAction(ISD::SUB, VT, Legal);
 
       // For v2i64, these are only valid with P8Vector. This is corrected after
       // the loop.
+      if (VT.getSizeInBits() <= 128 && VT.getScalarSizeInBits() <= 64) {
         setOperationAction(ISD::SMAX, VT, Legal);
         setOperationAction(ISD::SMIN, VT, Legal);
         setOperationAction(ISD::UMAX, VT, Legal);
         setOperationAction(ISD::UMIN, VT, Legal);
+      }
+      else {
+        setOperationAction(ISD::SMAX, VT, Expand);
+        setOperationAction(ISD::SMIN, VT, Expand);
+        setOperationAction(ISD::UMAX, VT, Expand);
+        setOperationAction(ISD::UMIN, VT, Expand);
+      }
 
       if (Subtarget.hasVSX()) {
         setOperationAction(ISD::FMAXNUM, VT, Legal);
         setOperationAction(ISD::FMINNUM, VT, Legal);
       }
 
       // Vector instructions introduced in P8
       if (Subtarget.hasP8Altivec() && (VT.SimpleTy != MVT::v1i128)) {

llvm/test/CodeGen/PowerPC/vec-min-max.ll

 ; NOP8VEC-NEXT:    xvmindp 34, 34, 35
 ; NOP8VEC-NEXT:    blr
 entry:
   %0 = fcmp fast ole <2 x double> %a, %b
   %1 = select <2 x i1> %0, <2 x double> %a, <2 x double> %b
   ret <2 x double> %1
 }
 
+define i128 @invalidv1i128(<2 x i128> %v1, <2 x i128> %v2) {
+; CHECK-LABEL: invalidv1i128:
+; CHECK-LABEL: %bb.1:
+; CHECK-NEXT: vmr
+; NOP8VEC-LABEL: invalidv1i128:
+; NOP8VEC: isel
+; NOP8VEC: isel
+%1 = icmp slt <2 x i128> %v1, %v2
+%2 = select <2 x i1> %1, <2 x i128> %v1, <2 x i128> %v2
+%3 = extractelement <2 x i128> %2, i32 0
+ret i128 %3
+}