Recommit "[ConstraintElimination] Change debug output to display variable names."

This reverts commit 02ae7e7.

include Value.h in ConstraintSystem.h

Author: Zain Jaffal

llvm/include/llvm/Analysis/ConstraintSystem.h

@@ -36,13 +36,17 @@ class ConstraintSystem {
   // Eliminate constraints from the system using Fourier–Motzkin elimination.
   bool eliminateUsingFM();
 
-  /// Print the constraints in the system, using x0...xn as variable names.
-  void dump() const;
-
   /// Returns true if there may be a solution for the constraints in the system.
   bool mayHaveSolutionImpl();
 
+  /// Get list of variable names from the Value2Index map.
+  SmallVector<std::string> getVarNamesList() const;
+
 public:
+  ConstraintSystem() {}
+  ConstraintSystem(const DenseMap<Value *, unsigned> &Value2Index)
+      : Value2Index(Value2Index) {}
+
   bool addVariableRow(ArrayRef<int64_t> R) {
     assert(Constraints.empty() || R.size() == Constraints.back().size());
     // If all variable coefficients are 0, the constraint does not provide any
@@ -103,8 +107,8 @@ class ConstraintSystem {
   /// Returns the number of rows in the constraint system.
   unsigned size() const { return Constraints.size(); }
 
-  /// Print the constraints in the system, using \p Names as variable names.
-  void dump(ArrayRef<std::string> Names) const;
+  /// Print the constraints in the system.
+  void dump() const;
 };
 } // namespace llvm
 

llvm/lib/Analysis/ConstraintSystem.cpp

@@ -10,6 +10,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/IR/Value.h"
 #include "llvm/Support/Debug.h"
 
 #include <string>
@@ -111,10 +112,23 @@ bool ConstraintSystem::mayHaveSolutionImpl() {
   return all_of(Constraints, [](auto &R) { return R[0] >= 0; });
 }
 
-void ConstraintSystem::dump(ArrayRef<std::string> Names) const {
+SmallVector<std::string> ConstraintSystem::getVarNamesList() const {
+  SmallVector<std::string> Names(Value2Index.size(), "");
+  for (auto &[V, Index] : Value2Index) {
+    std::string OperandName;
+    if (V->getName().empty())
+      OperandName = V->getNameOrAsOperand();
+    else
+      OperandName = std::string("%") + V->getName().str();
+    Names[Index - 1] = OperandName;
+  }
+  return Names;
+}
+
+void ConstraintSystem::dump() const {
   if (Constraints.empty())
     return;
-
+  SmallVector<std::string> Names = getVarNamesList();
   for (const auto &Row : Constraints) {
     SmallVector<std::string, 16> Parts;
     for (unsigned I = 1, S = Row.size(); I < S; ++I) {
@@ -131,15 +145,8 @@ void ConstraintSystem::dump(ArrayRef<std::string> Names) const {
   }
 }
 
-void ConstraintSystem::dump() const {
-  SmallVector<std::string, 16> Names;
-  for (unsigned i = 1; i < Constraints.back().size(); ++i)
-    Names.push_back("x" + std::to_string(i));
-  LLVM_DEBUG(dbgs() << "---\n");
-  dump(Names);
-}
-
 bool ConstraintSystem::mayHaveSolution() {
+  LLVM_DEBUG(dbgs() << "---\n");
   LLVM_DEBUG(dump());
   bool HasSolution = mayHaveSolutionImpl();
   LLVM_DEBUG(dbgs() << (HasSolution ? "sat" : "unsat") << "\n");

llvm/lib/Transforms/Scalar/ConstraintElimination.cpp

@@ -644,20 +644,12 @@ struct State {
 } // namespace
 
 #ifndef NDEBUG
-static void dumpWithNames(const ConstraintSystem &CS,
-                          DenseMap<Value *, unsigned> &Value2Index) {
-  SmallVector<std::string> Names(Value2Index.size(), "");
-  for (auto &KV : Value2Index) {
-    Names[KV.second - 1] = std::string("%") + KV.first->getName().str();
-  }
-  CS.dump(Names);
-}
 
-static void dumpWithNames(ArrayRef<int64_t> C,
-                          DenseMap<Value *, unsigned> &Value2Index) {
-  ConstraintSystem CS;
+static void dumpConstraint(ArrayRef<int64_t> C,
+                           const DenseMap<Value *, unsigned> &Value2Index) {
+  ConstraintSystem CS(Value2Index);
   CS.addVariableRowFill(C);
-  dumpWithNames(CS, Value2Index);
+  CS.dump();
 }
 #endif
 
@@ -941,7 +933,7 @@ static bool checkAndReplaceCondition(
 
     LLVM_DEBUG({
       dbgs() << "Condition " << *Cmp << " implied by dominating constraints\n";
-      dumpWithNames(CSToUse, Info.getValue2Index(R.IsSigned));
+      CSToUse.dump();
     });
     generateReproducer(Cmp, ReproducerModule, ReproducerCondStack, Info, DT);
     Constant *TrueC =
@@ -961,7 +953,7 @@ static bool checkAndReplaceCondition(
 
     LLVM_DEBUG({
       dbgs() << "Condition !" << *Cmp << " implied by dominating constraints\n";
-      dumpWithNames(CSToUse, Info.getValue2Index(R.IsSigned));
+      CSToUse.dump(); 
     });
     generateReproducer(Cmp, ReproducerModule, ReproducerCondStack, Info, DT);
     Constant *FalseC =
@@ -1005,7 +997,7 @@ void ConstraintInfo::addFact(CmpInst::Predicate Pred, Value *A, Value *B,
 
     LLVM_DEBUG({
       dbgs() << "  constraint: ";
-      dumpWithNames(R.Coefficients, getValue2Index(R.IsSigned));
+      dumpConstraint(R.Coefficients, getValue2Index(R.IsSigned));
       dbgs() << "\n";
     });
 
@@ -1150,8 +1142,8 @@ static bool eliminateConstraints(Function &F, DominatorTree &DT,
         break;
       LLVM_DEBUG({
         dbgs() << "Removing ";
-        dumpWithNames(Info.getCS(E.IsSigned).getLastConstraint(),
-                      Info.getValue2Index(E.IsSigned));
+        dumpConstraint(Info.getCS(E.IsSigned).getLastConstraint(),
+                       Info.getValue2Index(E.IsSigned));
         dbgs() << "\n";
       });
 

llvm/test/Transforms/ConstraintElimination/reproducer-remarks-debug.ll

@@ -5,7 +5,7 @@
 target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 
 ; CHECK:      Condition   %c.2 = icmp eq ptr %a, null implied by dominating constraints
-; CHECK-NEXT: %a + -1 * % <= 0
+; CHECK-NEXT: %a + -1 * null <= 0
 ; CHECK-NEXT: Creating reproducer for   %c.2 = icmp eq ptr %a, null
 ; CHECK-NEXT:   found external input ptr %a
 ; CHECK-NEXT:   Materializing assumption   %c.1 = icmp eq ptr %a, null