[ASTImporter] Import fix of GCCAsmStmts w/ missing symbolic operands

[gerazo]

Summary

Do not drop the import of the whole function just because an asm statement in it has some missing symbolic names.

[a.sidorin]

Hello Zoltan,
Thank you for the patch. There is an inline comment.

lib/AST/ASTImporter.cpp

5221

In such cases, we should check that FromIdentifier is nullptr too (to detect cases where the result is nullptr due to import error). The check will be still present but will look like:

if (!ToII && S->getOutputIdentifier())
  return nullptr;

The same below.

[gerazo]

Better check not letting a real import problem passing through

[gerazo]

lib/AST/ASTImporter.cpp

5221

Thank you Aleksei, done.

[a.sidorin]

Looks good, thank you!

lib/AST/ASTImporter.cpp

Stmt *ASTNodeImporter::VisitStmt(Stmt *S) {
    return nullptr;
  }
 
 
 Stmt *ASTNodeImporter::VisitGCCAsmStmt(GCCAsmStmt *S) {
   SmallVector<IdentifierInfo *, 4> Names;
   for (unsigned I = 0, E = S->getNumOutputs(); I != E; I++) {
     IdentifierInfo *ToII = Importer.Import(S->getOutputIdentifier(I));
-    if (!ToII)
-      return nullptr;
+    // ToII is nullptr when no symbolic name is given for output operand
+    // see ParseStmtAsm::ParseAsmOperandsOpt
     Names.push_back(ToII);
   }
   for (unsigned I = 0, E = S->getNumInputs(); I != E; I++) {
     IdentifierInfo *ToII = Importer.Import(S->getInputIdentifier(I));
-    if (!ToII)
-      return nullptr;
+    // ToII is nullptr when no symbolic name is given for input operand
+    // see ParseStmtAsm::ParseAsmOperandsOpt
     Names.push_back(ToII);
   }
 
   SmallVector<StringLiteral *, 4> Clobbers;
   for (unsigned I = 0, E = S->getNumClobbers(); I != E; I++) {
     StringLiteral *Clobber = cast_or_null<StringLiteral>(
           Importer.Import(S->getClobberStringLiteral(I)));
     if (!Clobber)

test/ASTMerge/asm/Inputs/asm-function.cpp

 
 unsigned char asmFunc(unsigned char a, unsigned char b) {
   unsigned int la = a;
   unsigned int lb = b;
   unsigned int bigres;
   unsigned char res;
   __asm__ ("0:\n1:\n" : [bigres] "=la"(bigres) : [la] "0"(la), [lb] "c"(lb) :
                         "edx", "cc");
   res = bigres;
   return res;
 }
+
+int asmFunc2(int i) {
+  int res;
+  asm ("mov %1, %0 \t\n"
+       "inc %0 "
+      : "=r" (res)
+      : "r" (i)
+      : "cc");
+  return res;
+}

test/ASTMerge/asm/test.cpp

 // RUN: %clang_cc1 -triple i386-unknown-unknown -fcxx-exceptions -emit-pch -o %t.1.ast %S/Inputs/asm-function.cpp
 // RUN: %clang_cc1 -triple i386-unknown-unknown -fcxx-exceptions -ast-merge %t.1.ast -fsyntax-only -verify %s
 // expected-no-diagnostics
 
 void testAsmImport() {
   asmFunc(12, 42);
+  asmFunc2(42);
 }