[llvm] [PowerPC] Implement Context Switch Instr mtlpl (PR #160593)

[Lei Huang via llvm-commits]

https://github.com/lei137 updated https://github.com/llvm/llvm-project/pull/160593

>From 47e9da54eed2c129029527d82662fdd663c6e511 Mon Sep 17 00:00:00 2001
From: Lei Huang <lei at ca.ibm.com>
Date: Fri, 17 Oct 2025 16:27:50 +0000
Subject: [PATCH 1/2] [PowerPC] Implement Context Switch Instr mtlpl

---
 llvm/lib/Target/PowerPC/PPCInstrFuture.td     | 20 +++++++++++++++++++
 .../PowerPC/ppc-encoding-ISAFuture.txt        |  3 +++
 .../PowerPC/ppc64le-encoding-ISAFuture.txt    |  3 +++
 llvm/test/MC/PowerPC/ppc-encoding-ISAFuture.s |  4 ++++
 4 files changed, 30 insertions(+)

diff --git a/llvm/lib/Target/PowerPC/PPCInstrFuture.td b/llvm/lib/Target/PowerPC/PPCInstrFuture.td
index 1aefea1a1c498..02312dfc74215 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrFuture.td
+++ b/llvm/lib/Target/PowerPC/PPCInstrFuture.td
@@ -182,6 +182,20 @@ class XX3Form_XTAB6<bits<6> opcode, bits<8> xo, dag OOL, dag IOL, string asmstr,
   let Inst{31} = XT{5};
 }
 
+class XForm_RBS5<bits<6> opCode, bits<10> xo, dag OOL, dag IOL, string asmstr,
+                 InstrItinClass itin, list<dag> pattern>
+    : I<opCode, OOL, IOL, asmstr, itin> {
+
+  bits<5> RB;
+  bits<5> RS;
+
+  let Pattern = pattern;
+
+  let Inst{6...10} = RS;
+  let Inst{16...20} = RB;
+  let Inst{21...30} = xo;
+}
+
 class XX3Form_XTAB6_S<bits<5> xo, dag OOL, dag IOL, string asmstr,
                        list<dag> pattern>
     : I<59, OOL, IOL, asmstr, NoItinerary> {
@@ -294,6 +308,12 @@ let Predicates = [IsISAFuture] in {
   defm SUBFUS : XOForm_RTAB5_L1r<31, 72, (outs g8rc:$RT),
                                  (ins g8rc:$RA, g8rc:$RB, u1imm:$L), "subfus",
                                  "$RT, $L, $RA, $RB", []>;
+  def MTLPL : XForm_RBS5<31, 275, (outs), (ins gprc:$RB, gprc:$RS),
+                         "mtlpl $RB, $RS", IIC_SprMTSPR, []>;
+  let Interpretation64Bit = 1, isCodeGenOnly = 1 in {
+    def MTLPL8 : XForm_RBS5<31, 275, (outs), (ins g8rc:$RB, g8rc:$RS),
+                            "mtlpl $RB, $RS", IIC_SprMTSPR, []>, isPPC64;
+  }
 }
 
 let Predicates = [HasVSX, IsISAFuture] in {
diff --git a/llvm/test/MC/Disassembler/PowerPC/ppc-encoding-ISAFuture.txt b/llvm/test/MC/Disassembler/PowerPC/ppc-encoding-ISAFuture.txt
index cdfc8ce9e0ca5..b53ec3abe62de 100644
--- a/llvm/test/MC/Disassembler/PowerPC/ppc-encoding-ISAFuture.txt
+++ b/llvm/test/MC/Disassembler/PowerPC/ppc-encoding-ISAFuture.txt
@@ -274,6 +274,9 @@
 #CHECK: xvmulhuh  4, 5, 7
 0xf0,0x85,0x3b,0xd0
 
+#CHECK: mtlpl 3, 4
+0x7c,0x80,0x1a,0x26
+
 #CHECK: xxmulmul 8, 3, 4, 2
 0xed,0x03,0x22,0x08
 
diff --git a/llvm/test/MC/Disassembler/PowerPC/ppc64le-encoding-ISAFuture.txt b/llvm/test/MC/Disassembler/PowerPC/ppc64le-encoding-ISAFuture.txt
index f7e314fc819e4..3a6aeb469d1ea 100644
--- a/llvm/test/MC/Disassembler/PowerPC/ppc64le-encoding-ISAFuture.txt
+++ b/llvm/test/MC/Disassembler/PowerPC/ppc64le-encoding-ISAFuture.txt
@@ -268,6 +268,9 @@
 #CHECK: xvmulhuh  4, 5, 7
 0xd0,0x3b,0x85,0xf0
 
+#CHECK: mtlpl 3, 4
+0x26,0x1a,0x80,0x7c
+
 #CHECK: xxmulmul 8, 3, 4, 2
 0x08,0x22,0x03,0xed
 
diff --git a/llvm/test/MC/PowerPC/ppc-encoding-ISAFuture.s b/llvm/test/MC/PowerPC/ppc-encoding-ISAFuture.s
index 29fedd7c20646..f1a2a825fb021 100644
--- a/llvm/test/MC/PowerPC/ppc-encoding-ISAFuture.s
+++ b/llvm/test/MC/PowerPC/ppc-encoding-ISAFuture.s
@@ -387,6 +387,10 @@
 #CHECK-BE: xvmulhuh 4, 5, 7              # encoding: [0xf0,0x85,0x3b,0xd0]
 #CHECK-LE: xvmulhuh 4, 5, 7              # encoding: [0xd0,0x3b,0x85,0xf0]
 
+           mtlpl 3, 4
+#CHECK-BE: mtlpl 3, 4                     # encoding: [0x7c,0x80,0x1a,0x26]
+#CHECK-LE: mtlpl 3, 4                     # encoding: [0x26,0x1a,0x80,0x7c]
+
            xxmulmul 8, 3, 4, 2
 #CHECK-BE: xxmulmul 8, 3, 4, 2          # encoding: [0xed,0x03,0x22,0x08]
 #CHECK-LE: xxmulmul 8, 3, 4, 2          # encoding: [0x08,0x22,0x03,0xed]

>From 5041c71c5ee43a6cc80920189d372078c159131c Mon Sep 17 00:00:00 2001
From: Lei Huang <lei at ca.ibm.com>
Date: Fri, 24 Oct 2025 20:48:40 +0000
Subject: [PATCH 2/2] explicitly set all non-used fields to 0

---
 llvm/lib/Target/PowerPC/PPCInstrFuture.td | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/llvm/lib/Target/PowerPC/PPCInstrFuture.td b/llvm/lib/Target/PowerPC/PPCInstrFuture.td
index 02312dfc74215..19e5876a2d9bf 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrFuture.td
+++ b/llvm/lib/Target/PowerPC/PPCInstrFuture.td
@@ -192,8 +192,10 @@ class XForm_RBS5<bits<6> opCode, bits<10> xo, dag OOL, dag IOL, string asmstr,
   let Pattern = pattern;
 
   let Inst{6...10} = RS;
+  let Inst{11...15} = 0;
   let Inst{16...20} = RB;
   let Inst{21...30} = xo;
+  let Inst{31} = 0;
 }
 
 class XX3Form_XTAB6_S<bits<5> xo, dag OOL, dag IOL, string asmstr,