[llvm] [GlobalISel] Refactor Combiner MatchData & Apply C++ Code Handling (PR #92239)

[Matt Arsenault via llvm-commits]

================
@@ -1780,6 +1811,44 @@ bool CombineRuleBuilder::emitApplyPatterns(CodeExpansions &CE, RuleMatcher &M) {
   return true;
 }
 
+bool CombineRuleBuilder::emitCXXMatchApply(CodeExpansions &CE, RuleMatcher &M,
+                                           ArrayRef<CXXPattern *> Matchers) {
+  assert(hasOnlyCXXApplyPatterns());
+  declareAllMatchDatasExpansions(CE);
+
+  std::string CodeStr;
+  raw_string_ostream OS(CodeStr);
+
+  for (auto &MD : MatchDatas)
+    OS << MD.Type << " " << MD.getVarName() << ";\n";
+
+  if (!Matchers.empty()) {
+    OS << "// Match Patterns\n";
+    for (auto *M : Matchers) {
+      OS << "if(![&](){";
+      CodeExpander Expander(M->getRawCode(), CE, RuleDef.getLoc(),
+                            /*ShowExpansions*/ false);
----------------
arsenm wrote:

```suggestion
                            /*ShowExpansions=*/ false);
```

https://github.com/llvm/llvm-project/pull/92239