[mips] Implementation of dli.

    
Patch by David Chisnall
His work was sponsored by: DARPA, AFRL
    
Some small modifications to the original patch: we now error if
it's not possible to expand an instruction (mips-expansions-bad.s has some
examples). Added some comments to the expansions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211271 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 97 insertions, 7 deletions

diff --git a/lib/Target/Mips/AsmParser/MipsAsmParser.cpp b/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
index 8f46820ff7..dc9ed2feeb 100644
--- a/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
+++ b/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
@@ -984,6 +984,7 @@ bool MipsAsmParser::needsExpansion(MCInst &Inst) {
   case Mips::LoadImm32Reg:
   case Mips::LoadAddr32Imm:
   case Mips::LoadAddr32Reg:
+  case Mips::LoadImm64Reg:
     return true;
   default:
     return false;
@@ -997,6 +998,12 @@ bool MipsAsmParser::expandInstruction(MCInst &Inst, SMLoc IDLoc,
     return true;
   case Mips::LoadImm32Reg:
     return expandLoadImm(Inst, IDLoc, Instructions);
+  case Mips::LoadImm64Reg:
+    if (!isGP64()) {
+      Error(IDLoc, "instruction requires a CPU feature not currently enabled");
+      return true;
+    }
+    return expandLoadImm(Inst, IDLoc, Instructions);
   case Mips::LoadAddr32Imm:
     return expandLoadAddressImm(Inst, IDLoc, Instructions);
   case Mips::LoadAddr32Reg:
@@ -1004,6 +1011,30 @@ bool MipsAsmParser::expandInstruction(MCInst &Inst, SMLoc IDLoc,
   }
 }
 
+namespace {
+template <int Shift, bool PerformShift>
+void createShiftOr(int64_t Value, unsigned RegNo, SMLoc IDLoc,
+                   SmallVectorImpl<MCInst> &Instructions) {
+  MCInst tmpInst;
+  if (PerformShift) {
+    tmpInst.setOpcode(Mips::DSLL);
+    tmpInst.addOperand(MCOperand::CreateReg(RegNo));
+    tmpInst.addOperand(MCOperand::CreateReg(RegNo));
+    tmpInst.addOperand(MCOperand::CreateImm(16));
+    tmpInst.setLoc(IDLoc);
+    Instructions.push_back(tmpInst);
+    tmpInst.clear();
+  }
+  tmpInst.setOpcode(Mips::ORi);
+  tmpInst.addOperand(MCOperand::CreateReg(RegNo));
+  tmpInst.addOperand(MCOperand::CreateReg(RegNo));
+  tmpInst.addOperand(
+      MCOperand::CreateImm(((Value & (0xffffLL << Shift)) >> Shift)));
+  tmpInst.setLoc(IDLoc);
+  Instructions.push_back(tmpInst);
+}
+}
+
 bool MipsAsmParser::expandLoadImm(MCInst &Inst, SMLoc IDLoc,
                                   SmallVectorImpl<MCInst> &Instructions) {
   MCInst tmpInst;
@@ -1012,8 +1043,10 @@ bool MipsAsmParser::expandLoadImm(MCInst &Inst, SMLoc IDLoc,
   const MCOperand &RegOp = Inst.getOperand(0);
   assert(RegOp.isReg() && "expected register operand kind");
 
-  int ImmValue = ImmOp.getImm();
+  int64_t ImmValue = ImmOp.getImm();
   tmpInst.setLoc(IDLoc);
+  // FIXME: gas has a special case for values that are 000...1111, which
+  // becomes a li -1 and then a dsrl
   if (0 <= ImmValue && ImmValue <= 65535) {
     // For 0 <= j <= 65535.
     // li d,j => ori d,$zero,j
@@ -1030,21 +1063,71 @@ bool MipsAsmParser::expandLoadImm(MCInst &Inst, SMLoc IDLoc,
     tmpInst.addOperand(MCOperand::CreateReg(Mips::ZERO));
     tmpInst.addOperand(MCOperand::CreateImm(ImmValue));
     Instructions.push_back(tmpInst);
-  } else {
-    // For any other value of j that is representable as a 32-bit integer.
+  } else if ((ImmValue & 0xffffffff) == ImmValue) {
+    // For any value of j that is representable as a 32-bit integer, create
+    // a sequence of:
     // li d,j => lui d,hi16(j)
     //           ori d,d,lo16(j)
     tmpInst.setOpcode(Mips::LUi);
     tmpInst.addOperand(MCOperand::CreateReg(RegOp.getReg()));
     tmpInst.addOperand(MCOperand::CreateImm((ImmValue & 0xffff0000) >> 16));
     Instructions.push_back(tmpInst);
-    tmpInst.clear();
-    tmpInst.setOpcode(Mips::ORi);
+    createShiftOr<0, false>(ImmValue, RegOp.getReg(), IDLoc, Instructions);
+  } else if ((ImmValue & (0xffffLL << 48)) == 0) {
+    if (!isGP64()) {
+      Error (IDLoc, "instruction requires a CPU feature not currently enabled");
+      return true;
+    }
+
+    //            <-------  lo32 ------>
+    // <-------  hi32 ------>
+    // <- hi16 ->             <- lo16 ->
+    //  _________________________________
+    // |          |          |          |
+    // | 16-bytes | 16-bytes | 16-bytes |
+    // |__________|__________|__________|
+    //
+    // For any value of j that is representable as a 48-bit integer, create
+    // a sequence of:
+    // li d,j => lui d,hi16(j)
+    //           ori d,d,hi16(lo32(j))
+    //           dsll d,d,16
+    //           ori d,d,lo16(lo32(j))
+    tmpInst.setOpcode(Mips::LUi);
     tmpInst.addOperand(MCOperand::CreateReg(RegOp.getReg()));
+    tmpInst.addOperand(
+        MCOperand::CreateImm((ImmValue & (0xffffLL << 32)) >> 32));
+    Instructions.push_back(tmpInst);
+    createShiftOr<16, false>(ImmValue, RegOp.getReg(), IDLoc, Instructions);
+    createShiftOr<0, true>(ImmValue, RegOp.getReg(), IDLoc, Instructions);
+  } else {
+    if (!isGP64()) {
+      Error (IDLoc, "instruction requires a CPU feature not currently enabled");
+      return true;
+    }
+
+    // <-------  hi32 ------> <-------  lo32 ------>
+    // <- hi16 ->                        <- lo16 ->
+    //  ___________________________________________
+    // |          |          |          |          |
+    // | 16-bytes | 16-bytes | 16-bytes | 16-bytes |
+    // |__________|__________|__________|__________|
+    //
+    // For any value of j that isn't representable as a 48-bit integer.
+    // li d,j => lui d,hi16(j)
+    //           ori d,d,lo16(hi32(j))
+    //           dsll d,d,16
+    //           ori d,d,hi16(lo32(j))
+    //           dsll d,d,16
+    //           ori d,d,lo16(lo32(j))
+    tmpInst.setOpcode(Mips::LUi);
     tmpInst.addOperand(MCOperand::CreateReg(RegOp.getReg()));
-    tmpInst.addOperand(MCOperand::CreateImm(ImmValue & 0xffff));
-    tmpInst.setLoc(IDLoc);
+    tmpInst.addOperand(
+        MCOperand::CreateImm((ImmValue & (0xffffLL << 48)) >> 48));
     Instructions.push_back(tmpInst);
+    createShiftOr<32, false>(ImmValue, RegOp.getReg(), IDLoc, Instructions);
+    createShiftOr<16, true>(ImmValue, RegOp.getReg(), IDLoc, Instructions);
+    createShiftOr<0, true>(ImmValue, RegOp.getReg(), IDLoc, Instructions);
   }
   return false;
 }
diff --git a/lib/Target/Mips/Mips64InstrInfo.td b/lib/Target/Mips/Mips64InstrInfo.td
index 88422ce19d..2b9cda7ac8 100644
--- a/lib/Target/Mips/Mips64InstrInfo.td
+++ b/lib/Target/Mips/Mips64InstrInfo.td
@@ -23,6 +23,8 @@ def uimm16_64      : Operand<i64> {
 // Signed Operand
 def simm10_64 : Operand<i64>;
 
+def imm64: Operand<i64>;
+
 // Transformation Function - get Imm - 32.
 def Subtract32 : SDNodeXForm<imm, [{
   return getImm(N, (unsigned)N->getZExtValue() - 32);
@@ -486,6 +488,11 @@ def : MipsInstAlias<"dsrl $rd, $rt, $rs",
                     (DSRLV GPR64Opnd:$rd, GPR64Opnd:$rt, GPR32Opnd:$rs), 0>,
                     ISA_MIPS3;
 
+class LoadImm64< string instr_asm, Operand Od, RegisterOperand RO> :
+  MipsAsmPseudoInst<(outs RO:$rt), (ins Od:$imm64),
+                     !strconcat(instr_asm, "\t$rt, $imm64")> ;
+def LoadImm64Reg : LoadImm64<"dli", imm64, GPR64Opnd>;
+
 /// Move between CPU and coprocessor registers
 let DecoderNamespace = "Mips64", Predicates = [HasMips64] in {
 def DMFC0 : MFC3OP<"dmfc0", GPR64Opnd>, MFC3OP_FM<0x10, 1>;