[clang] Implementation of '#pragma STDC FENV_ROUND' (PR #89617)

[Joshua Cranmer via cfe-commits]

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@@ -5980,6 +5987,64 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
   return Ret;
 }
 
+static bool endsWithRoundingModeSuffix(StringRef FuncName) {
+  size_t Underscore = FuncName.find_last_of("_");
+  if (Underscore == StringRef::npos || Underscore < 2)
+    return false;
+  StringRef Suffix = FuncName.substr(Underscore + 1);
+  static const StringRef RMSuffixes[] = {"rtz", "rte", "rtp", "rtn", "rhaz",
+                                         "rz",  "rn",  "ru",  "rd"};
+  for (auto RM : RMSuffixes) {
+    if (Suffix == RM)
+      return true;
+  }
+  return false;
+}
+
+bool CodeGenFunction::requiresDynamicRounding(const CGCallee &Callee) {
+  if (Callee.isOrdinary()) {
+    const Decl *CalleeDecl = Callee.getAbstractInfo().getCalleeDecl().getDecl();
+    if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(CalleeDecl)) {
+      IdentifierInfo *FuncNameII = FD->getDeclName().getAsIdentifierInfo();
+      if (FuncNameII) {
+        StringRef FuncName = FuncNameII->getName();
+        // If a reserved identifier ends with rounding mode suffix preceded by
+        // underscore, this function does not need the previous dynamic rounding
+        // mode to be set.
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jcranmer-intel wrote:

Where is this rule coming from?

https://github.com/llvm/llvm-project/pull/89617