[PATCH] D24193: Allow variables with asm labels in naked functions

[Nikola Smiljanić via cfe-commits]

nikola updated this revision to Diff 70985.
nikola added a comment.

This should address Hans' comments, as for the code get I have no idea. I was hoping someone more knowledgeable would tell me if this made sense or not?


https://reviews.llvm.org/D24193

Files:
  lib/Sema/SemaDecl.cpp
  test/Sema/attr-naked.c

Index: test/Sema/attr-naked.c
===================================================================
--- test/Sema/attr-naked.c
+++ test/Sema/attr-naked.c
@@ -48,3 +48,21 @@
                "r"(z) // expected-error{{parameter references not allowed in naked functions}}
            );
 }
+
+__attribute__((naked)) void t10() {  // expected-note{{attribute is here}}
+  int a; // expected-error{{non-ASM statement in naked function is not supported}}
+}
+
+__attribute__((naked)) void t11() {  // expected-note{{attribute is here}}
+  register int a asm("eax") = x; // expected-error{{non-ASM statement in naked function is not supported}}
+}
+
+__attribute__((naked)) void t12() {  // expected-note{{attribute is here}}
+  register int a asm("eax"), b asm("ebx") = x; // expected-error{{non-ASM statement in naked function is not supported}}
+}
+
+__attribute__((naked)) void t13() {
+  register int a asm("eax");
+  register int b asm("ebx"), c asm("ecx");
+}
+
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -11792,6 +11792,21 @@
 
     if (FD && FD->hasAttr<NakedAttr>()) {
       for (const Stmt *S : Body->children()) {
+        // Allow local register variables without initializer as they don't
+        // require prologue.
+        bool RegisterVariables = false;
+        if (auto *DS = dyn_cast<DeclStmt>(S)) {
+          for (const auto *Decl : DS->decls()) {
+            if (const auto *Var = dyn_cast<VarDecl>(Decl)) {
+              RegisterVariables =
+                  Var->hasAttr<AsmLabelAttr>() && !Var->hasInit();
+              if (!RegisterVariables)
+                break;
+            }
+          }
+        }
+        if (RegisterVariables)
+          continue;
         if (!isa<AsmStmt>(S) && !isa<NullStmt>(S)) {
           Diag(S->getLocStart(), diag::err_non_asm_stmt_in_naked_function);
           Diag(FD->getAttr<NakedAttr>()->getLocation(), diag::note_attribute);


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