[llvm] [GlobalISel] Prefix MatchTable Lines with their Index (PR #125845)

[Pierre van Houtryve via llvm-commits]

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@@ -286,11 +286,28 @@ MatchTableRecord MatchTable::JumpTarget(unsigned LabelID) {
 void MatchTable::emitUse(raw_ostream &OS) const { OS << "MatchTable" << ID; }
 
 void MatchTable::emitDeclaration(raw_ostream &OS) const {
-  unsigned Indentation = 4;
+  static constexpr unsigned BaseIndent = 4;
+  unsigned Indentation = 0;
   OS << "  constexpr static uint8_t MatchTable" << ID << "[] = {";
   LineBreak.emit(OS, true, *this);
-  OS << std::string(Indentation, ' ');
 
+  // We want to display the table index of each line in a consistent
+  // manner. It has to appear as a column on the left side of the table.
+  // To determine how wide the column needs to be, check how many characters
+  // we need to fit the largest possible index in the current table.
+  const unsigned NumColsForIdx = llvm::to_string(CurrentSize).size();
+
+  unsigned CurIndex = 0;
+  const auto BeginLine = [&]() {
+    OS.indent(BaseIndent);
+    std::string IdxStr = llvm::to_string(CurIndex);
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Pierre-vh wrote:

How? I need its size to calculate the padding to insert


https://github.com/llvm/llvm-project/pull/125845