[PATCH] D77850: [PowerPC] Exploit rldimi for ori with large immediates

[Qiu Chaofan via Phabricator via llvm-commits]

qiucf created this revision.
qiucf added reviewers: PowerPC, jsji, nemanjai, steven.zhang, shchenz.
Herald added subscribers: llvm-commits, kbarton, hiraditya.
Herald added a project: LLVM.

This patch exploits `rldimi` instruction for patterns like `or %a, 0b000011110000`, which saves number of instructions in some cases, compared with `li-ori-sldi-or`.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D77850

Files:
  llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
  llvm/test/CodeGen/PowerPC/ori_imm32.ll
  llvm/test/CodeGen/PowerPC/ori_imm64.ll


Index: llvm/test/CodeGen/PowerPC/ori_imm64.ll
===================================================================
--- llvm/test/CodeGen/PowerPC/ori_imm64.ll
+++ llvm/test/CodeGen/PowerPC/ori_imm64.ll
@@ -15,10 +15,8 @@
 define i64 @ori_test_2(i64 %a) {
 ; CHECK-LABEL: ori_test_2:
 ; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:    lis 4, 15
-; CHECK-NEXT:    ori 4, 4, 65535
-; CHECK-NEXT:    sldi 4, 4, 29
-; CHECK-NEXT:    or 3, 3, 4
+; CHECK-NEXT:    li 4, -1
+; CHECK-NEXT:    rldimi 3, 4, 29, 15
 ; CHECK-NEXT:    blr
 entry:
   %or = or i64 %a, 562949416550400 ; 0x1ffffe0000000
@@ -28,9 +26,8 @@
 define i64 @ori_test_3(i64 %a) {
 ; CHECK-LABEL: ori_test_3:
 ; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:    lis 4, -32768
-; CHECK-NEXT:    rldicr 4, 4, 36, 63
-; CHECK-NEXT:    or 3, 3, 4
+; CHECK-NEXT:    li 4, -1
+; CHECK-NEXT:    rldimi 3, 4, 3, 28
 ; CHECK-NEXT:    blr
 entry:
   %or = or i64 %a, 68719476728 ; 0xffffffff8
Index: llvm/test/CodeGen/PowerPC/ori_imm32.ll
===================================================================
--- llvm/test/CodeGen/PowerPC/ori_imm32.ll
+++ llvm/test/CodeGen/PowerPC/ori_imm32.ll
@@ -16,9 +16,8 @@
 define i64 @ori_test_b(i64 %a) {
 ; CHECK-LABEL: ori_test_b:
 ; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:    li 4, 1
-; CHECK-NEXT:    sldi 4, 4, 32
-; CHECK-NEXT:    or 3, 3, 4
+; CHECK-NEXT:    li 4, -1
+; CHECK-NEXT:    rldimi 3, 4, 32, 31
 ; CHECK-NEXT:    blr
 entry:
   %or = or i64 %a, 4294967296
Index: llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
===================================================================
--- llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -351,6 +351,7 @@
     bool tryAsSingleRLWINM(SDNode *N);
     bool tryAsSingleRLWINM8(SDNode *N);
     bool tryAsSingleRLWIMI(SDNode *N);
+    bool tryAsSingleRLDIMI(SDNode *N);
 
     void PeepholePPC64();
     void PeepholePPC64ZExt();
@@ -4542,6 +4543,28 @@
   return true;
 }
 
+bool PPCDAGToDAGISel::tryAsSingleRLDIMI(SDNode *N) {
+  assert(N->getOpcode() == ISD::OR && "ISD::OR SDNode expected");
+  uint64_t Imm64;
+  unsigned MB, ME;
+
+  // We won't get fewer instructions if the immediate is 32-bit integer.
+  // rldimi requires the immediate to have sequent ones with both sides zero.
+  if (!isInt64Immediate(N->getOperand(1).getNode(), Imm64) ||
+      isUInt<32>(Imm64) || !isRunOfOnes64(Imm64, MB, ME))
+    return false;
+
+  unsigned SH = 63 - ME;
+  SDLoc Dl(N);
+  // Use select64Imm for making LI instr instead of directly putting Imm64
+  SDValue Ops[] = {
+      N->getOperand(0),
+      SDValue(selectI64Imm(CurDAG, getI64Imm(-1, Dl).getNode()), 0),
+      getI32Imm(SH, Dl), getI32Imm(MB, Dl)};
+  CurDAG->SelectNodeTo(N, PPC::RLDIMI, MVT::i64, Ops);
+  return true;
+}
+
 // Select - Convert the specified operand from a target-independent to a
 // target-specific node if it hasn't already been changed.
 void PPCDAGToDAGISel::Select(SDNode *N) {
@@ -4789,6 +4812,11 @@
       }
     }
 
+    // If this is 'or' against an imm with sequent ones and both sides zero,
+    // try to emit rldimi
+    if (tryAsSingleRLDIMI(N))
+      return;
+
     // OR with a 32-bit immediate can be handled by ori + oris
     // without creating an immediate in a GPR.
     uint64_t Imm64 = 0;


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D77850.256484.patch
Type: text/x-patch
Size: 3290 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20200410/d6cda290/attachment.bin>