1 files changed, 189 insertions, 0 deletions
diff --git a/llvm/utils/TableGen/DAGISelEmitter.cpp b/llvm/utils/TableGen/DAGISelEmitter.cpp
new file mode 100644
index 000000000000..d8e78ce55c7b
--- /dev/null
+++ b/llvm/utils/TableGen/DAGISelEmitter.cpp
@@ -0,0 +1,189 @@
+//===- DAGISelEmitter.cpp - Generate an instruction selector --------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This tablegen backend emits a DAG instruction selector.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CodeGenDAGPatterns.h"
+#include "DAGISelMatcher.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/TableGen/Record.h"
+#include "llvm/TableGen/TableGenBackend.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "dag-isel-emitter"
+
+namespace {
+/// DAGISelEmitter - The top-level class which coordinates construction
+/// and emission of the instruction selector.
+class DAGISelEmitter {
+  CodeGenDAGPatterns CGP;
+public:
+  explicit DAGISelEmitter(RecordKeeper &R) : CGP(R) {}
+  void run(raw_ostream &OS);
+};
+} // End anonymous namespace
+
+//===----------------------------------------------------------------------===//
+// DAGISelEmitter Helper methods
+//
+
+/// getResultPatternCost - Compute the number of instructions for this pattern.
+/// This is a temporary hack.  We should really include the instruction
+/// latencies in this calculation.
+static unsigned getResultPatternCost(TreePatternNode *P,
+                                     CodeGenDAGPatterns &CGP) {
+  if (P->isLeaf()) return 0;
+
+  unsigned Cost = 0;
+  Record *Op = P->getOperator();
+  if (Op->isSubClassOf("Instruction")) {
+    Cost++;
+    CodeGenInstruction &II = CGP.getTargetInfo().getInstruction(Op);
+    if (II.usesCustomInserter)
+      Cost += 10;
+  }
+  for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i)
+    Cost += getResultPatternCost(P->getChild(i), CGP);
+  return Cost;
+}
+
+/// getResultPatternCodeSize - Compute the code size of instructions for this
+/// pattern.
+static unsigned getResultPatternSize(TreePatternNode *P,
+                                     CodeGenDAGPatterns &CGP) {
+  if (P->isLeaf()) return 0;
+
+  unsigned Cost = 0;
+  Record *Op = P->getOperator();
+  if (Op->isSubClassOf("Instruction")) {
+    Cost += Op->getValueAsInt("CodeSize");
+  }
+  for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i)
+    Cost += getResultPatternSize(P->getChild(i), CGP);
+  return Cost;
+}
+
+namespace {
+// PatternSortingPredicate - return true if we prefer to match LHS before RHS.
+// In particular, we want to match maximal patterns first and lowest cost within
+// a particular complexity first.
+struct PatternSortingPredicate {
+  PatternSortingPredicate(CodeGenDAGPatterns &cgp) : CGP(cgp) {}
+  CodeGenDAGPatterns &CGP;
+
+  bool operator()(const PatternToMatch *LHS, const PatternToMatch *RHS) {
+    const TreePatternNode *LT = LHS->getSrcPattern();
+    const TreePatternNode *RT = RHS->getSrcPattern();
+
+    MVT LHSVT = LT->getNumTypes() != 0 ? LT->getSimpleType(0) : MVT::Other;
+    MVT RHSVT = RT->getNumTypes() != 0 ? RT->getSimpleType(0) : MVT::Other;
+    if (LHSVT.isVector() != RHSVT.isVector())
+      return RHSVT.isVector();
+
+    if (LHSVT.isFloatingPoint() != RHSVT.isFloatingPoint())
+      return RHSVT.isFloatingPoint();
+
+    // Otherwise, if the patterns might both match, sort based on complexity,
+    // which means that we prefer to match patterns that cover more nodes in the
+    // input over nodes that cover fewer.
+    int LHSSize = LHS->getPatternComplexity(CGP);
+    int RHSSize = RHS->getPatternComplexity(CGP);
+    if (LHSSize > RHSSize) return true;   // LHS -> bigger -> less cost
+    if (LHSSize < RHSSize) return false;
+
+    // If the patterns have equal complexity, compare generated instruction cost
+    unsigned LHSCost = getResultPatternCost(LHS->getDstPattern(), CGP);
+    unsigned RHSCost = getResultPatternCost(RHS->getDstPattern(), CGP);
+    if (LHSCost < RHSCost) return true;
+    if (LHSCost > RHSCost) return false;
+
+    unsigned LHSPatSize = getResultPatternSize(LHS->getDstPattern(), CGP);
+    unsigned RHSPatSize = getResultPatternSize(RHS->getDstPattern(), CGP);
+    if (LHSPatSize < RHSPatSize) return true;
+    if (LHSPatSize > RHSPatSize) return false;
+
+    // Sort based on the UID of the pattern, to reflect source order.
+    // Note that this is not guaranteed to be unique, since a single source
+    // pattern may have been resolved into multiple match patterns due to
+    // alternative fragments.  To ensure deterministic output, always use
+    // std::stable_sort with this predicate.
+    return LHS->ID < RHS->ID;
+  }
+};
+} // End anonymous namespace
+
+
+void DAGISelEmitter::run(raw_ostream &OS) {
+  emitSourceFileHeader("DAG Instruction Selector for the " +
+                       CGP.getTargetInfo().getName().str() + " target", OS);
+
+  OS << "// *** NOTE: This file is #included into the middle of the target\n"
+     << "// *** instruction selector class.  These functions are really "
+     << "methods.\n\n";
+
+  OS << "// If GET_DAGISEL_DECL is #defined with any value, only function\n"
+        "// declarations will be included when this file is included.\n"
+        "// If GET_DAGISEL_BODY is #defined, its value should be the name of\n"
+        "// the instruction selector class. Function bodies will be emitted\n"
+        "// and each function's name will be qualified with the name of the\n"
+        "// class.\n"
+        "//\n"
+        "// When neither of the GET_DAGISEL* macros is defined, the functions\n"
+        "// are emitted inline.\n\n";
+
+  LLVM_DEBUG(errs() << "\n\nALL PATTERNS TO MATCH:\n\n";
+             for (CodeGenDAGPatterns::ptm_iterator I = CGP.ptm_begin(),
+                  E = CGP.ptm_end();
+                  I != E; ++I) {
+               errs() << "PATTERN: ";
+               I->getSrcPattern()->dump();
+               errs() << "\nRESULT:  ";
+               I->getDstPattern()->dump();
+               errs() << "\n";
+             });
+
+  // Add all the patterns to a temporary list so we can sort them.
+  std::vector<const PatternToMatch*> Patterns;
+  for (CodeGenDAGPatterns::ptm_iterator I = CGP.ptm_begin(), E = CGP.ptm_end();
+       I != E; ++I)
+    Patterns.push_back(&*I);
+
+  // We want to process the matches in order of minimal cost.  Sort the patterns
+  // so the least cost one is at the start.
+  std::stable_sort(Patterns.begin(), Patterns.end(),
+                   PatternSortingPredicate(CGP));
+
+
+  // Convert each variant of each pattern into a Matcher.
+  std::vector<Matcher*> PatternMatchers;
+  for (unsigned i = 0, e = Patterns.size(); i != e; ++i) {
+    for (unsigned Variant = 0; ; ++Variant) {
+      if (Matcher *M = ConvertPatternToMatcher(*Patterns[i], Variant, CGP))
+        PatternMatchers.push_back(M);
+      else
+        break;
+    }
+  }
+
+  std::unique_ptr<Matcher> TheMatcher =
+    std::make_unique<ScopeMatcher>(PatternMatchers);
+
+  OptimizeMatcher(TheMatcher, CGP);
+  //Matcher->dump();
+  EmitMatcherTable(TheMatcher.get(), CGP, OS);
+}
+
+namespace llvm {
+
+void EmitDAGISel(RecordKeeper &RK, raw_ostream &OS) {
+  DAGISelEmitter(RK).run(OS);
+}
+
+} // End llvm namespace