Move checkNRVO() from func.d to funcsem.d (#16536)

Co-authored-by: Alex Muscar <alex@muscar.eu>
dlang · Jun 1, 2024 · 4de90c7 · 4de90c7
1 parent e9a3680
commit 4de90c7
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Showing 2 changed files with 56 additions and 52 deletions.
diff --git a/compiler/src/dmd/func.d b/compiler/src/dmd/func.d
@@ -1557,58 +1557,6 @@ extern (C++) class FuncDeclaration : Declaration
  return fd;
  }
 
- /***********************************************
- * Check all return statements for a function to verify that returning
- * using NRVO is possible.
- *
- * Returns:
- * `false` if the result cannot be returned by hidden reference.
- */
- extern (D) final bool checkNRVO()
- {
- if (!isNRVO() || returns is null)
- return false;
-
- auto tf = type.toTypeFunction();
- if (tf.isref)
- return false;
-
- foreach (rs; *returns)
- {
- if (auto ve = rs.exp.isVarExp())
- {
- auto v = ve.var.isVarDeclaration();
- if (!v || v.isReference())
- return false;
- else if (nrvo_var is null)
- {
- // Variables in the data segment (e.g. globals, TLS or not),
- // parameters and closure variables cannot be NRVOed.
- if (v.isDataseg() || v.isParameter() || v.toParent2() != this)
- return false;
- if (v.nestedrefs.length && needsClosure())
- return false;
- // don't know if the return storage is aligned
- version (MARS)
- {
- if (alignSectionVars && (*alignSectionVars).contains(v))
- return false;
- }
- // The variable type needs to be equivalent to the return type.
- if (!v.type.equivalent(tf.next))
- return false;
- //printf("Setting nrvo to %s\n", v.toChars());
- nrvo_var = v;
- }
- else if (nrvo_var != v)
- return false;
- }
- else //if (!exp.isLvalue()) // keep NRVO-ability
- return false;
- }
- return true;
- }
-
  override final inout(FuncDeclaration) isFuncDeclaration() inout
  {
  return this;

diff --git a/compiler/src/dmd/funcsem.d b/compiler/src/dmd/funcsem.d
@@ -65,6 +65,10 @@ import dmd.tokens;
 import dmd.typesem;
 import dmd.visitor;
 
+version (IN_GCC) {}
+else version (IN_LLVM) {}
+else version = MARS;
+
 /* Tweak all return statements and dtor call for nrvo_var, for correct NRVO.
  */
 extern (C++) final class NrvoWalker : StatementRewriteWalker
@@ -3006,3 +3010,55 @@ extern (D) void checkMain(FuncDeclaration fd)
  if (retType.ty != Tint32 && retType.ty != Tvoid && retType.ty != Tnoreturn)
  .error(fd.loc, "%s `%s` must return `int`, `void` or `noreturn`, not `%s`", fd.kind, fd.toPrettyChars, tf.nextOf().toChars());
 }
+
+/***********************************************
+ * Check all return statements for a function to verify that returning
+ * using NRVO is possible.
+ *
+ * Returns:
+ * `false` if the result cannot be returned by hidden reference.
+ */
+extern (D) bool checkNRVO(FuncDeclaration fd)
+{
+ if (!fd.isNRVO() || fd.returns is null)
+ return false;
+
+ auto tf = fd.type.toTypeFunction();
+ if (tf.isref)
+ return false;
+
+ foreach (rs; *fd.returns)
+ {
+ if (auto ve = rs.exp.isVarExp())
+ {
+ auto v = ve.var.isVarDeclaration();
+ if (!v || v.isReference())
+ return false;
+ else if (fd.nrvo_var is null)
+ {
+ // Variables in the data segment (e.g. globals, TLS or not),
+ // parameters and closure variables cannot be NRVOed.
+ if (v.isDataseg() || v.isParameter() || v.toParent2() != fd)
+ return false;
+ if (v.nestedrefs.length && fd.needsClosure())
+ return false;
+ // don't know if the return storage is aligned
+ version (MARS)
+ {
+ if (fd.alignSectionVars && (*fd.alignSectionVars).contains(v))
+ return false;
+ }
+ // The variable type needs to be equivalent to the return type.
+ if (!v.type.equivalent(tf.next))
+ return false;
+ //printf("Setting nrvo to %s\n", v.toChars());
+ fd.nrvo_var = v;
+ }
+ else if (fd.nrvo_var != v)
+ return false;
+ }
+ else //if (!exp.isLvalue()) // keep NRVO-ability
+ return false;
+ }
+ return true;
+}