[NFC] Fix evaluation order dependency in call arguments

[michael-jabbour-sonarsource]

The code in ARMAsmParser::parseDirectiveReq passes both parseRegister(Reg, SRegLoc, ERegLoc) and SRegLoc as arguments to check(). Since function arguments are indeterminately sequenced per C++17 [expr.call]/5, a compiler can evaluate SRegLoc before parseRegister() executes. This means check() receives a null location instead of the actual parsed source location for error reporting.

The fix separates the calls to establish explicit sequencing, ensuring check() receives the correct source location.

This issue was detected by the CFamily analyzer for SonarQube. I'm happy to provide any additional information or clarification as needed.

[llvmbot]

@llvm/pr-subscribers-backend-arm

Author: Michael Jabbour (michael-jabbour-sonarsource)

Changes

The code in ARMAsmParser::parseDirectiveReq passes both parseRegister(Reg, SRegLoc, ERegLoc) and SRegLoc as arguments to check(). Since function arguments are indeterminately sequenced per C++17 [expr.call]/5, a compiler can evaluate SRegLoc before parseRegister() executes. This means check() receives a null location instead of the actual parsed source location for error reporting.

The fix separates the calls to establish explicit sequencing, ensuring check() receives the correct source location.

This issue was detected by the CFamily analyzer for SonarQube. I'm happy to provide any additional information or clarification as needed.

---

Full diff: https://github.com/llvm/llvm-project/pull/141366.diff

1 Files Affected:

• (modified) llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp (+2-3)

diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 85b107c6085d3..ee3dc7d8a3618 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -11788,9 +11788,8 @@ bool ARMAsmParser::parseDirectiveReq(StringRef Name, SMLoc L) {
   Parser.Lex(); // Eat the '.req' token.
   MCRegister Reg;
   SMLoc SRegLoc, ERegLoc;
-  if (check(parseRegister(Reg, SRegLoc, ERegLoc), SRegLoc,
-            "register name expected") ||
-      parseEOL())
+  const bool parseResult = parseRegister(Reg, SRegLoc, ERegLoc);
+  if (check(parseResult, SRegLoc, "register name expected") || parseEOL())
     return true;
 
   if (RegisterReqs.insert(std::make_pair(Name, Reg)).first->second != Reg)

[davemgreen]

Sounds good. LGTM