[llvm] MC: Support quoted symbol names (PR #138817)

[Nikita Popov via llvm-commits]

================
@@ -212,6 +212,27 @@ MCDataFragment *MCContext::allocInitialFragment(MCSection &Sec) {
 MCSymbol *MCContext::getOrCreateSymbol(const Twine &Name) {
   SmallString<128> NameSV;
   StringRef NameRef = Name.toStringRef(NameSV);
+  if (NameRef.contains('\\')) {
+    NameSV = NameRef;
+    size_t S = 0;
+    // Support escaped \\ and \" as in GNU Assembler. GAS issues a warning for
+    // other characters following \\, which we do not implement due to code
+    // structure.
+    for (size_t I = 0, E = NameSV.size(); I < E; ++I) {
+      char C = NameSV[I];
+      if (C == '\\') {
+        switch (NameSV[I + 1]) {
+        case '"':
+        case '\\':
+          C = NameSV[++I];
+          break;
+        }
+      }
+      NameSV[S++] = C;
+    }
+    NameSV.resize(S);
+    NameRef = NameSV;
+  }
----------------
nikic wrote:

Yes, this is a problem. I put up https://github.com/llvm/llvm-project/pull/158106 to put at least some of these uses behind a common API.

A simple option would be to just keep StringRef and have the backing storage in an Allocator. This would avoid API changes and should not really be a performance or memory usage problem as long as quoted symbols are rare.

Though I'm not sure whether all uses of parseIdentifier should parse quoted strings or not.

https://github.com/llvm/llvm-project/pull/138817