[WebAssembly] Clean up CustomMappingTraits<BBNumberMap> (NFC)

[kazutakahirata]

This patch does two things for readability:

• Use structured bindings.
• Remove extraneous .c_str().

Note that YamlIO.mapRequired takes StringRef as the key type. As
such, we can implicitly construct StringRef from std::string.

[llvmbot]

@llvm/pr-subscribers-backend-webassembly

Author: Kazu Hirata (kazutakahirata)

Changes

This patch does two things for readability:

• Use structured bindings.
• Remove extraneous .c_str().

Note that YamlIO.mapRequired takes StringRef as the key type. As
such, we can implicitly construct StringRef from std::string.

---

Full diff: https://github.com/llvm/llvm-project/pull/167155.diff

1 Files Affected:

• (modified) llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h (+2-2)

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h b/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h
index ee575e3527673..0e913fb1ee669 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h
@@ -211,8 +211,8 @@ template <> struct CustomMappingTraits<BBNumberMap> {
   }
 
   static void output(IO &YamlIO, BBNumberMap &SrcToUnwindDest) {
-    for (auto KV : SrcToUnwindDest)
-      YamlIO.mapRequired(std::to_string(KV.first).c_str(), KV.second);
+    for (auto [Src, Dest] : SrcToUnwindDest)
+      YamlIO.mapRequired(std::to_string(Src), Dest);
   }
 };