[TableGen] Support encoding per-HwMode

Much like ValueTypeByHwMode/RegInfoByHwMode, this patch allows targets
to modify an instruction's encoding based on HwMode. When the
EncodingInfos field is non-empty the Inst and Size fields of the Instruction
are ignored and taken from EncodingInfos instead.

As part of this promote getHwMode() from TargetSubtargetInfo to MCSubtargetInfo.

This is NFC for all existing targets - new code is generated only if targets
use EncodingByHwMode.

llvm-svn: 372320

6 files changed, 179 insertions, 38 deletions

diff --git a/llvm/utils/TableGen/CodeEmitterGen.cpp b/llvm/utils/TableGen/CodeEmitterGen.cpp
index 10c42bbc6ff..b021d08881f 100644
--- a/llvm/utils/TableGen/CodeEmitterGen.cpp
+++ b/llvm/utils/TableGen/CodeEmitterGen.cpp
@@ -46,12 +46,17 @@ public:
 private:
   int getVariableBit(const std::string &VarName, BitsInit *BI, int bit);
   std::string getInstructionCase(Record *R, CodeGenTarget &Target);
+  std::string getInstructionCaseForEncoding(Record *R, Record *EncodingDef,
+                                            CodeGenTarget &Target);
   void AddCodeToMergeInOperand(Record *R, BitsInit *BI,
                                const std::string &VarName,
                                unsigned &NumberedOp,
                                std::set<unsigned> &NamedOpIndices,
                                std::string &Case, CodeGenTarget &Target);
 
+  void emitInstructionBaseValues(
+      raw_ostream &o, ArrayRef<const CodeGenInstruction *> NumberedInstructions,
+      CodeGenTarget &Target, int HwMode = -1);
   unsigned BitWidth;
   bool UseAPInt;
 };
@@ -261,7 +266,29 @@ AddCodeToMergeInOperand(Record *R, BitsInit *BI, const std::string &VarName,
 std::string CodeEmitterGen::getInstructionCase(Record *R,
                                                CodeGenTarget &Target) {
   std::string Case;
-  BitsInit *BI = R->getValueAsBitsInit("Inst");
+  if (const RecordVal *RV = R->getValue("EncodingInfos")) {
+    if (auto *DI = dyn_cast_or_null<DefInit>(RV->getValue())) {
+      const CodeGenHwModes &HWM = Target.getHwModes();
+      EncodingInfoByHwMode EBM(DI->getDef(), HWM);
+      Case += "      switch (HwMode) {\n";
+      Case += "      default: llvm_unreachable(\"Unhandled HwMode\");\n";
+      for (auto &KV : EBM.Map) {
+        Case += "      case " + itostr(KV.first) + ": {\n";
+        Case += getInstructionCaseForEncoding(R, KV.second, Target);
+        Case += "      break;\n";
+        Case += "      }\n";
+      }
+      Case += "      }\n";
+      return Case;
+    }
+  }
+  return getInstructionCaseForEncoding(R, R, Target);
+}
+
+std::string CodeEmitterGen::getInstructionCaseForEncoding(Record *R, Record *EncodingDef,
+                                                          CodeGenTarget &Target) {
+  std::string Case;
+  BitsInit *BI = EncodingDef->getValueAsBitsInit("Inst");
   unsigned NumberedOp = 0;
   std::set<unsigned> NamedOpIndices;
 
@@ -281,7 +308,7 @@ std::string CodeEmitterGen::getInstructionCase(Record *R,
 
   // Loop over all of the fields in the instruction, determining which are the
   // operands to the instruction.
-  for (const RecordVal &RV : R->getValues()) { 
+  for (const RecordVal &RV : EncodingDef->getValues()) {
     // Ignore fixed fields in the record, we're looking for values like:
     //    bits<5> RST = { ?, ?, ?, ?, ? };
     if (RV.getPrefix() || RV.getValue()->isComplete())
@@ -317,6 +344,47 @@ static void emitInstBits(raw_ostream &OS, const APInt &Bits) {
        << ")";
 }
 
+void CodeEmitterGen::emitInstructionBaseValues(
+    raw_ostream &o, ArrayRef<const CodeGenInstruction *> NumberedInstructions,
+    CodeGenTarget &Target, int HwMode) {
+  const CodeGenHwModes &HWM = Target.getHwModes();
+  if (HwMode == -1)
+    o << "  static const uint64_t InstBits[] = {\n";
+  else
+    o << "  static const uint64_t InstBits_" << HWM.getMode(HwMode).Name
+      << "[] = {\n";
+
+  for (const CodeGenInstruction *CGI : NumberedInstructions) {
+    Record *R = CGI->TheDef;
+
+    if (R->getValueAsString("Namespace") == "TargetOpcode" ||
+        R->getValueAsBit("isPseudo")) {
+      o << "    "; emitInstBits(o, APInt(BitWidth, 0)); o << ",\n";
+      continue;
+    }
+
+    Record *EncodingDef = R;
+    if (const RecordVal *RV = R->getValue("EncodingInfos")) {
+      if (auto *DI = dyn_cast_or_null<DefInit>(RV->getValue())) {
+        EncodingInfoByHwMode EBM(DI->getDef(), HWM);
+        EncodingDef = EBM.get(HwMode);
+      }
+    }
+    BitsInit *BI = EncodingDef->getValueAsBitsInit("Inst");
+
+    // Start by filling in fixed values.
+    APInt Value(BitWidth, 0);
+    for (unsigned i = 0, e = BI->getNumBits(); i != e; ++i) {
+      if (BitInit *B = dyn_cast<BitInit>(BI->getBit(e - i - 1)))
+        Value |= APInt(BitWidth, (uint64_t)B->getValue()) << (e - i - 1);
+    }
+    o << "    ";
+    emitInstBits(o, Value);
+    o << "," << '\t' << "// " << R->getName() << "\n";
+  }
+  o << "    UINT64_C(0)\n  };\n";
+}
+
 void CodeEmitterGen::run(raw_ostream &o) {
   CodeGenTarget Target(Records);
   std::vector<Record*> Insts = Records.getAllDerivedDefinitions("Instruction");
@@ -327,17 +395,29 @@ void CodeEmitterGen::run(raw_ostream &o) {
   ArrayRef<const CodeGenInstruction*> NumberedInstructions =
     Target.getInstructionsByEnumValue();
 
-  // Default to something sensible in case the target doesn't define Inst.
-  BitWidth = 32;
+  const CodeGenHwModes &HWM = Target.getHwModes();
+  // The set of HwModes used by instruction encodings.
+  std::set<unsigned> HwModes;
+  BitWidth = 0;
   for (const CodeGenInstruction *CGI : NumberedInstructions) {
     Record *R = CGI->TheDef;
     if (R->getValueAsString("Namespace") == "TargetOpcode" ||
         R->getValueAsBit("isPseudo"))
       continue;
 
+    if (const RecordVal *RV = R->getValue("EncodingInfos")) {
+      if (DefInit *DI = dyn_cast_or_null<DefInit>(RV->getValue())) {
+        EncodingInfoByHwMode EBM(DI->getDef(), HWM);
+        for (auto &KV : EBM.Map) {
+          BitsInit *BI = KV.second->getValueAsBitsInit("Inst");
+          BitWidth = std::max(BitWidth, BI->getNumBits());
+          HwModes.insert(KV.first);
+        }
+        continue;
+      }
+    }
     BitsInit *BI = R->getValueAsBitsInit("Inst");
-    BitWidth = BI->getNumBits();
-    break;
+    BitWidth = std::max(BitWidth, BI->getNumBits());
   }
   UseAPInt = BitWidth > 64;
   
@@ -357,31 +437,25 @@ void CodeEmitterGen::run(raw_ostream &o) {
   }
   
   // Emit instruction base values
-  o << "  static const uint64_t InstBits[] = {\n";
-  for (const CodeGenInstruction *CGI : NumberedInstructions) {
-    Record *R = CGI->TheDef;
-
-    if (R->getValueAsString("Namespace") == "TargetOpcode" ||
-        R->getValueAsBit("isPseudo")) {
-      o << "    "; emitInstBits(o, APInt(BitWidth, 0)); o << ",\n";
-      continue;
-    }
-
-    BitsInit *BI = R->getValueAsBitsInit("Inst");
-    BitWidth = BI->getNumBits();
+  if (HwModes.empty()) {
+    emitInstructionBaseValues(o, NumberedInstructions, Target, -1);
+  } else {
+    for (unsigned HwMode : HwModes)
+      emitInstructionBaseValues(o, NumberedInstructions, Target, (int)HwMode);
+  }
 
-    // Start by filling in fixed values.
-    APInt Value(BitWidth, 0);
-    for (unsigned i = 0, e = BI->getNumBits(); i != e; ++i) {
-      if (BitInit *B = dyn_cast<BitInit>(BI->getBit(e - i - 1)))
-        Value |= APInt(BitWidth, (uint64_t)B->getValue()) << (e - i - 1);
+  if (!HwModes.empty()) {
+    o << "  const uint64_t *InstBits;\n";
+    o << "  unsigned HwMode = STI.getHwMode();\n";
+    o << "  switch (HwMode) {\n";
+    o << "  default: llvm_unreachable(\"Unknown hardware mode!\"); break;\n";
+    for (unsigned I : HwModes) {
+      o << "  case " << I << ": InstBits = InstBits_" << HWM.getMode(I).Name
+        << "; break;\n";
     }
-    o << "    ";
-    emitInstBits(o, Value);
-    o << "," << '\t' << "// " << R->getName() << "\n";
+    o << "  };\n";
   }
-  o << "    UINT64_C(0)\n  };\n";
-  
+
   // Map to accumulate all the cases.
   std::map<std::string, std::vector<std::string>> CaseMap;
 
diff --git a/llvm/utils/TableGen/CodeGenTarget.cpp b/llvm/utils/TableGen/CodeGenTarget.cpp
index 478bbb7e480..fa8b842c97f 100644
--- a/llvm/utils/TableGen/CodeGenTarget.cpp
+++ b/llvm/utils/TableGen/CodeGenTarget.cpp
@@ -478,7 +478,8 @@ void CodeGenTarget::reverseBitsForLittleEndianEncoding() {
   if (!isLittleEndianEncoding())
     return;
 
-  std::vector<Record*> Insts = Records.getAllDerivedDefinitions("Instruction");
+  std::vector<Record *> Insts =
+      Records.getAllDerivedDefinitions("InstructionEncoding");
   for (Record *R : Insts) {
     if (R->getValueAsString("Namespace") == "TargetOpcode" ||
         R->getValueAsBit("isPseudo"))
diff --git a/llvm/utils/TableGen/FixedLenDecoderEmitter.cpp b/llvm/utils/TableGen/FixedLenDecoderEmitter.cpp
index 01f4115aa1d..ac69b431607 100644
--- a/llvm/utils/TableGen/FixedLenDecoderEmitter.cpp
+++ b/llvm/utils/TableGen/FixedLenDecoderEmitter.cpp
@@ -13,6 +13,7 @@
 
 #include "CodeGenInstruction.h"
 #include "CodeGenTarget.h"
+#include "InfoByHwMode.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/CachedHashString.h"
@@ -97,9 +98,11 @@ struct DecoderTableInfo {
 struct EncodingAndInst {
   const Record *EncodingDef;
   const CodeGenInstruction *Inst;
+  StringRef HwModeName;
 
-  EncodingAndInst(const Record *EncodingDef, const CodeGenInstruction *Inst)
-      : EncodingDef(EncodingDef), Inst(Inst) {}
+  EncodingAndInst(const Record *EncodingDef, const CodeGenInstruction *Inst,
+                  StringRef HwModeName = "")
+      : EncodingDef(EncodingDef), Inst(Inst), HwModeName(HwModeName) {}
 };
 
 struct EncodingIDAndOpcode {
@@ -2382,12 +2385,50 @@ void FixedLenDecoderEmitter::run(raw_ostream &o) {
   Target.reverseBitsForLittleEndianEncoding();
 
   // Parameterize the decoders based on namespace and instruction width.
+  std::set<StringRef> HwModeNames;
   const auto &NumberedInstructions = Target.getInstructionsByEnumValue();
   NumberedEncodings.reserve(NumberedInstructions.size());
   DenseMap<Record *, unsigned> IndexOfInstruction;
+  // First, collect all HwModes referenced by the target.
   for (const auto &NumberedInstruction : NumberedInstructions) {
     IndexOfInstruction[NumberedInstruction->TheDef] = NumberedEncodings.size();
-    NumberedEncodings.emplace_back(NumberedInstruction->TheDef, NumberedInstruction);
+
+    if (const RecordVal *RV =
+            NumberedInstruction->TheDef->getValue("EncodingInfos")) {
+      if (auto *DI = dyn_cast_or_null<DefInit>(RV->getValue())) {
+        const CodeGenHwModes &HWM = Target.getHwModes();
+        EncodingInfoByHwMode EBM(DI->getDef(), HWM);
+        for (auto &KV : EBM.Map)
+          HwModeNames.insert(HWM.getMode(KV.first).Name);
+      }
+    }
+  }
+
+  // If HwModeNames is empty, add the empty string so we always have one HwMode.
+  if (HwModeNames.empty())
+    HwModeNames.insert("");
+
+  for (const auto &NumberedInstruction : NumberedInstructions) {
+    IndexOfInstruction[NumberedInstruction->TheDef] = NumberedEncodings.size();
+
+    if (const RecordVal *RV =
+            NumberedInstruction->TheDef->getValue("EncodingInfos")) {
+      if (DefInit *DI = dyn_cast_or_null<DefInit>(RV->getValue())) {
+        const CodeGenHwModes &HWM = Target.getHwModes();
+        EncodingInfoByHwMode EBM(DI->getDef(), HWM);
+        for (auto &KV : EBM.Map) {
+          NumberedEncodings.emplace_back(KV.second, NumberedInstruction,
+                                         HWM.getMode(KV.first).Name);
+          HwModeNames.insert(HWM.getMode(KV.first).Name);
+        }
+        continue;
+      }
+    }
+    // This instruction is encoded the same on all HwModes. Emit it for all
+    // HwModes.
+    for (StringRef HwModeName : HwModeNames)
+      NumberedEncodings.emplace_back(NumberedInstruction->TheDef,
+                                     NumberedInstruction, HwModeName);
   }
   for (const auto &NumberedAlias : RK.getAllDerivedDefinitions("AdditionalEncoding"))
     NumberedEncodings.emplace_back(
@@ -2415,13 +2456,19 @@ void FixedLenDecoderEmitter::run(raw_ostream &o) {
       NumInstructions++;
     NumEncodings++;
 
-    StringRef DecoderNamespace = EncodingDef->getValueAsString("DecoderNamespace");
+    if (!Size)
+      continue;
 
-    if (Size) {
-      if (populateInstruction(Target, *EncodingDef, *Inst, i, Operands)) {
-        OpcMap[std::make_pair(DecoderNamespace, Size)].emplace_back(i, IndexOfInstruction.find(Def)->second);
-      } else
-        NumEncodingsOmitted++;
+    if (populateInstruction(Target, *EncodingDef, *Inst, i, Operands)) {
+      std::string DecoderNamespace =
+          EncodingDef->getValueAsString("DecoderNamespace");
+      if (!NumberedEncodings[i].HwModeName.empty())
+        DecoderNamespace +=
+            std::string("_") + NumberedEncodings[i].HwModeName.str();
+      OpcMap[std::make_pair(DecoderNamespace, Size)].emplace_back(
+          i, IndexOfInstruction.find(Def)->second);
+    } else {
+      NumEncodingsOmitted++;
     }
   }
 
diff --git a/llvm/utils/TableGen/InfoByHwMode.cpp b/llvm/utils/TableGen/InfoByHwMode.cpp
index d9662889a5d..7cd1b0f0813 100644
--- a/llvm/utils/TableGen/InfoByHwMode.cpp
+++ b/llvm/utils/TableGen/InfoByHwMode.cpp
@@ -192,6 +192,17 @@ void RegSizeInfoByHwMode::writeToStream(raw_ostream &OS) const {
   OS << '}';
 }
 
+EncodingInfoByHwMode::EncodingInfoByHwMode(Record *R, const CodeGenHwModes &CGH) {
+  const HwModeSelect &MS = CGH.getHwModeSelect(R);
+  for (const HwModeSelect::PairType &P : MS.Items) {
+    assert(P.second && P.second->isSubClassOf("InstructionEncoding") &&
+           "Encoding must subclass InstructionEncoding");
+    auto I = Map.insert({P.first, P.second});
+    assert(I.second && "Duplicate entry?");
+    (void)I;
+  }
+}
+
 namespace llvm {
   raw_ostream &operator<<(raw_ostream &OS, const ValueTypeByHwMode &T) {
     T.writeToStream(OS);
diff --git a/llvm/utils/TableGen/InfoByHwMode.h b/llvm/utils/TableGen/InfoByHwMode.h
index 9e5cc3d5f2a..d92e5901a7f 100644
--- a/llvm/utils/TableGen/InfoByHwMode.h
+++ b/llvm/utils/TableGen/InfoByHwMode.h
@@ -184,6 +184,11 @@ raw_ostream &operator<<(raw_ostream &OS, const ValueTypeByHwMode &T);
 raw_ostream &operator<<(raw_ostream &OS, const RegSizeInfo &T);
 raw_ostream &operator<<(raw_ostream &OS, const RegSizeInfoByHwMode &T);
 
+struct EncodingInfoByHwMode : public InfoByHwMode<Record*> {
+  EncodingInfoByHwMode(Record *R, const CodeGenHwModes &CGH);
+  EncodingInfoByHwMode() = default;
+};
+
 } // namespace llvm
 
 #endif // LLVM_UTILS_TABLEGEN_INFOBYHWMODE_H
diff --git a/llvm/utils/TableGen/SubtargetEmitter.cpp b/llvm/utils/TableGen/SubtargetEmitter.cpp
index 41589b6b10d..f9705723650 100644
--- a/llvm/utils/TableGen/SubtargetEmitter.cpp
+++ b/llvm/utils/TableGen/SubtargetEmitter.cpp
@@ -1746,7 +1746,10 @@ void SubtargetEmitter::emitGenMCSubtargetInfo(raw_ostream &OS) {
      << "    return " << Target << "_MC"
      << "::resolveVariantSchedClassImpl(SchedClass, MI, CPUID); \n";
   OS << "  }\n";
+  if (TGT.getHwModes().getNumModeIds() > 1)
+    OS << "  unsigned getHwMode() const override;\n";
   OS << "};\n";
+  EmitHwModeCheck(Target + "GenMCSubtargetInfo", OS);
 }
 
 void SubtargetEmitter::EmitMCInstrAnalysisPredicateFunctions(raw_ostream &OS) {