[bpf] add support for bpf pseudo instruction

Expose bpf pseudo load instruction via intrinsic. It is used by front-ends that
can encode file descriptors directly into IR instead of relying on relocations.

llvm-svn: 233396

2 files changed, 24 insertions, 1 deletions

diff --git a/llvm/lib/Target/BPF/BPFInstrInfo.td b/llvm/lib/Target/BPF/BPFInstrInfo.td
index 47001f01ff0..1ab7a7754cd 100644
--- a/llvm/lib/Target/BPF/BPFInstrInfo.td
+++ b/llvm/lib/Target/BPF/BPFInstrInfo.td
@@ -257,6 +257,29 @@ class LD_IMM64<bits<4> Pseudo, string OpcodeStr>
 }
 def LD_imm64 : LD_IMM64<0, "ld_64">;
 
+def LD_pseudo
+    : InstBPF<(outs GPR:$dst), (ins i64imm:$pseudo, u64imm:$imm),
+              "ld_pseudo\t$dst, $pseudo, $imm",
+              [(set GPR:$dst, (int_bpf_pseudo imm:$pseudo, imm:$imm))]> {
+
+  bits<3> mode;
+  bits<2> size;
+  bits<4> dst;
+  bits<64> imm;
+  bits<4> pseudo;
+
+  let Inst{63-61} = mode;
+  let Inst{60-59} = size;
+  let Inst{51-48} = dst;
+  let Inst{55-52} = pseudo;
+  let Inst{47-32} = 0;
+  let Inst{31-0} = imm{31-0};
+
+  let mode = 0;     // BPF_IMM
+  let size = 3;     // BPF_DW
+  let BPFClass = 0; // BPF_LD
+}
+
 // STORE instructions
 class STORE<bits<2> SizeOp, string OpcodeStr, list<dag> Pattern>
     : InstBPF<(outs), (ins GPR:$src, MEMri:$addr),
diff --git a/llvm/lib/Target/BPF/MCTargetDesc/BPFMCCodeEmitter.cpp b/llvm/lib/Target/BPF/MCTargetDesc/BPFMCCodeEmitter.cpp
index 9c51d66dbc2..280d2f1e57f 100644
--- a/llvm/lib/Target/BPF/MCTargetDesc/BPFMCCodeEmitter.cpp
+++ b/llvm/lib/Target/BPF/MCTargetDesc/BPFMCCodeEmitter.cpp
@@ -125,7 +125,7 @@ void BPFMCCodeEmitter::EncodeInstruction(const MCInst &MI, raw_ostream &OS,
   // Keep track of the current byte being emitted
   unsigned CurByte = 0;
 
-  if (Opcode == BPF::LD_imm64) {
+  if (Opcode == BPF::LD_imm64 || Opcode == BPF::LD_pseudo) {
     uint64_t Value = getBinaryCodeForInstr(MI, Fixups, STI);
     EmitByte(Value >> 56, CurByte, OS);
     EmitByte(((Value >> 48) & 0xff), CurByte, OS);