[PATCH] D139813: [PowerPC] Improve materialization for immediates which is almost a 32 bit splat.

[Esme Yi via Phabricator via llvm-commits]

Esme updated this revision to Diff 482368.
Esme added a comment.

Address comments.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D139813/new/

https://reviews.llvm.org/D139813

Files:
  llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
  llvm/test/CodeGen/PowerPC/constants-i64.ll


Index: llvm/test/CodeGen/PowerPC/constants-i64.ll
===================================================================
--- llvm/test/CodeGen/PowerPC/constants-i64.ll
+++ llvm/test/CodeGen/PowerPC/constants-i64.ll
@@ -380,8 +380,7 @@
 ; CHECK:       # %bb.0: # %entry
 ; CHECK-NEXT:  lis 3, -13105
 ; CHECK-NEXT:  ori 3, 3, 52479
-; CHECK-NEXT:  rldic 3, 3, 32, 0
-; CHECK-NEXT:  oris 3, 3, 52431
+; CHECK-NEXT:  rldimi 3, 3, 32, 0
 ; CHECK-NEXT:  ori 3, 3, 291
 ; CHECK-NEXT:  blr
 entry:
@@ -393,9 +392,8 @@
 ; CHECK:       # %bb.0: # %entry
 ; CHECK-NEXT:  lis 3, -13057
 ; CHECK-NEXT:  ori 3, 3, 52479
-; CHECK-NEXT:  rldic 3, 3, 32, 0
+; CHECK-NEXT:  rldimi 3, 3, 32, 0
 ; CHECK-NEXT:  oris 3, 3, 291
-; CHECK-NEXT:  ori 3, 3, 52479
 ; CHECK-NEXT:  blr
 entry:
   ret i64 14771750698406366463 ;0xCCFFCCFF0123CCFF
Index: llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
===================================================================
--- llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -1328,6 +1328,43 @@
                                     getI32Imm(Lo16));
     ++InstCntDirect;
   }
+
+  // Try to use 4 instructions to materialize the immediate which is "almost" a
+  // splat of a 32 bit immediate.
+  if (InstCntDirect > 4) {
+    uint32_t Hi16OfHi32 = (Hi_32(Imm) >> 16) & 0xffff;
+    uint32_t Lo16OfHi32 = Hi_32(Imm) & 0xffff;
+    uint32_t Hi16OfLo32 = (Lo_32(Imm) >> 16) & 0xffff;
+    uint32_t Lo16OfLo32 = Lo_32(Imm) & 0xffff;
+
+    auto getSplat = [CurDAG, dl](uint32_t Hi16, uint32_t Lo16) {
+      auto getI32Imm = [CurDAG, dl](unsigned Imm) {
+        return CurDAG->getTargetConstant(Imm, dl, MVT::i32);
+      };
+      SDNode *Result =
+          CurDAG->getMachineNode(PPC::LIS8, dl, MVT::i64, getI32Imm(Hi16));
+      Result = CurDAG->getMachineNode(PPC::ORI8, dl, MVT::i64,
+                                      SDValue(Result, 0), getI32Imm(Lo16));
+      SDValue Ops[] = {SDValue(Result, 0), SDValue(Result, 0), getI32Imm(32),
+                       getI32Imm(0)};
+      return CurDAG->getMachineNode(PPC::RLDIMI, dl, MVT::i64, Ops);
+    };
+
+    if (Hi16OfHi32 == Hi16OfLo32) {
+      InstCntDirect = 4;
+      Result = getSplat(Hi16OfHi32, Lo16OfHi32);
+      Result = CurDAG->getMachineNode(
+          PPC::ORI8, dl, MVT::i64, SDValue(Result, 0),
+          CurDAG->getTargetConstant(Lo16OfLo32, dl, MVT::i32));
+    } else if (Lo16OfHi32 == Lo16OfLo32) {
+      InstCntDirect = 4;
+      Result = getSplat(Hi16OfHi32, Lo16OfHi32);
+      Result = CurDAG->getMachineNode(
+          PPC::ORIS8, dl, MVT::i64, SDValue(Result, 0),
+          CurDAG->getTargetConstant(Hi16OfLo32, dl, MVT::i32));
+    }
+  }
+
   if (InstCnt)
     *InstCnt = InstCntDirect;
   return Result;


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