[CodeGen] Support freeze expand for ppc_fp128

[ZhangKang]

Summary

The patch https://reviews.llvm.org/D29014 has added the new ISD::FREEZE and can deal with the integer.
The patch https://reviews.llvm.org/D76980 has added SoftenFloatRes_FREEZE for float point.

But from below code, we can know ppc_fp128, it needs expand.

1193   // ppcf128 type is really two f64's.
1194   if (!isTypeLegal(MVT::ppcf128)) {
1195     if (isTypeLegal(MVT::f64)) {
1196       NumRegistersForVT[MVT::ppcf128] = 2*NumRegistersForVT[MVT::f64];
1197       RegisterTypeForVT[MVT::ppcf128] = MVT::f64;
1198       TransformToType[MVT::ppcf128] = MVT::f64;
1199       ValueTypeActions.setTypeAction(MVT::ppcf128, TypeExpandFloat);
1200     } else {
1201       NumRegistersForVT[MVT::ppcf128] = NumRegistersForVT[MVT::i128];
1202       RegisterTypeForVT[MVT::ppcf128] = RegisterTypeForVT[MVT::i128];
1203       TransformToType[MVT::ppcf128] = MVT::i128;
1204       ValueTypeActions.setTypeAction(MVT::ppcf128, TypeSoftenFloat);
1205     }
1206   }

Some cases have gotten assertion for lack of expand for ppc_fp128. For example, below case:
cat ppcf128.mir

--- |
  define ppc_fp128 @freeze_select(ppc_fp128 %a, ppc_fp128 %b) {
    %sel.frozen = freeze ppc_fp128 %a
    %cmp = fcmp one ppc_fp128 %sel.frozen, 0xM00000000000000000000000000000000
    br i1 %cmp, label %select.end, label %select.false

  select.false:                                     ; preds = %0
    br label %select.end

  select.end:                                       ; preds = %0, %select.false
    %sel = phi ppc_fp128 [ %a, %0 ], [ %b, %select.false ]
    ret ppc_fp128 %sel
  }
...

Using below command:

llc -mtriple powerpc64le-unknown-linux-gnu -start-after=codegenprepare ppcf128.mir

You will get below error:

ExpandFloatResult #0: t33: ppcf128 = freeze t9

Do not know how to expand the result of this operator!
UNREACHABLE executed at /home/shkzhang/llvm/llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp:1122!

This patch is to support freeze expand for ppc_fp128 to fix the above error.

[efriedma]

Maybe change the name of the test to ppcf128-freeze.mir? Otherwise LGTM

[ZhangKang]

Rename the case name from ppcf128.mir to ppcf128_freeze.mir.

[ZhangKang]

Rename the case.

llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp

#endif
   case ISD::FNEARBYINT: ExpandFloatRes_FNEARBYINT(N, Lo, Hi); break;
   case ISD::FNEG:       ExpandFloatRes_FNEG(N, Lo, Hi); break;
   case ISD::STRICT_FP_EXTEND:
   case ISD::FP_EXTEND:  ExpandFloatRes_FP_EXTEND(N, Lo, Hi); break;
   case ISD::STRICT_FPOW:
   case ISD::FPOW:       ExpandFloatRes_FPOW(N, Lo, Hi); break;
   case ISD::STRICT_FPOWI:
   case ISD::FPOWI:      ExpandFloatRes_FPOWI(N, Lo, Hi); break;
+  case ISD::FREEZE:     ExpandFloatRes_FREEZE(N, Lo, Hi); break;
   case ISD::STRICT_FRINT:
   case ISD::FRINT:      ExpandFloatRes_FRINT(N, Lo, Hi); break;
   case ISD::STRICT_FROUND:
   case ISD::FROUND:     ExpandFloatRes_FROUND(N, Lo, Hi); break;
   case ISD::STRICT_FSIN:
   case ISD::FSIN:       ExpandFloatRes_FSIN(N, Lo, Hi); break;
   case ISD::STRICT_FSQRT:
   case ISD::FSQRT:      ExpandFloatRes_FSQRT(N, Lo, Hi); break;

 void DAGTypeLegalizer::ExpandFloatRes_FPOWI(SDNode *N,
                                             SDValue &Lo, SDValue &Hi) {
   ExpandFloatRes_Binary(N, GetFPLibCall(N->getValueType(0),
                                         RTLIB::POWI_F32, RTLIB::POWI_F64,
                                         RTLIB::POWI_F80, RTLIB::POWI_F128,
                                         RTLIB::POWI_PPCF128), Lo, Hi);
 }
 
+void DAGTypeLegalizer::ExpandFloatRes_FREEZE(SDNode *N,
+                                             SDValue &Lo, SDValue &Hi) {
+  assert(N->getValueType(0) == MVT::ppcf128 &&
+         "Logic only correct for ppcf128!");
+
+  SDLoc dl(N);
+  GetExpandedFloat(N->getOperand(0), Lo, Hi);
+  Lo = DAG.getNode(ISD::FREEZE, dl, Lo.getValueType(), Lo);
+  Hi = DAG.getNode(ISD::FREEZE, dl, Hi.getValueType(), Hi);
+}
+
 void DAGTypeLegalizer::ExpandFloatRes_FREM(SDNode *N,
                                            SDValue &Lo, SDValue &Hi) {
   ExpandFloatRes_Binary(N, GetFPLibCall(N->getValueType(0),
                                         RTLIB::REM_F32, RTLIB::REM_F64,
                                         RTLIB::REM_F80, RTLIB::REM_F128,
                                         RTLIB::REM_PPCF128), Lo, Hi);
 }
 

llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h

private:
   void ExpandFloatRes_FLOG10    (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FMA       (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FMUL      (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FNEARBYINT(SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FNEG      (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FP_EXTEND (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FPOW      (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FPOWI     (SDNode *N, SDValue &Lo, SDValue &Hi);
+  void ExpandFloatRes_FREEZE    (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FREM      (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FRINT     (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FROUND    (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FSIN      (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FSQRT     (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FSUB      (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FTRUNC    (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_LOAD      (SDNode *N, SDValue &Lo, SDValue &Hi);

llvm/test/CodeGen/PowerPC/ppcf128_freeze.mir

+# RUN: llc -mtriple powerpc64le-unknown-linux-gnu -start-after=codegenprepare \
+# RUN:   -o - %s -verify-machineinstrs | FileCheck %s
+
+--- |
+  define ppc_fp128 @freeze_select(ppc_fp128 %a, ppc_fp128 %b) {
+    %sel.frozen = freeze ppc_fp128 %a
+    %cmp = fcmp one ppc_fp128 %sel.frozen, 0xM00000000000000000000000000000000
+    br i1 %cmp, label %select.end, label %select.false
+
+  select.false:                                     ; preds = %0
+    br label %select.end
+
+  select.end:                                       ; preds = %0, %select.false
+    %sel = phi ppc_fp128 [ %a, %0 ], [ %b, %select.false ]
+    ret ppc_fp128 %sel
+  }
+
+  ; CHECK-LABEL: freeze_select
+  ; CHECK:       # %bb.0:
+  ; CHECK-NEXT:    xxlxor 0, 0, 0
+  ; CHECK-NEXT:    fcmpu 5, 2, 2
+  ; CHECK-NEXT:    fcmpu 1, 1, 1
+  ; CHECK-NEXT:    fcmpu 6, 2, 0
+  ; CHECK-NEXT:    fcmpu 0, 1, 0
+  ; CHECK-NEXT:    crnor 20, 23, 26
+  ; CHECK-NEXT:    crand 20, 2, 20
+  ; CHECK-NEXT:    bclr 12, 20, 0
+  ; CHECK-NEXT:  # %bb.1:
+  ; CHECK-NEXT:    crnor 20, 7, 2
+  ; CHECK-NEXT:    bclr 12, 20, 0
+  ; CHECK-NEXT:  # %bb.2:                                # %select.false
+  ; CHECK-NEXT:    fmr 1, 3
+  ; CHECK-NEXT:    fmr 2, 4
+  ; CHECK-NEXT:    blr
+...