move attribute(packed) sema support out of SemaDecl into a new SemaAttr.cpp file.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64711 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 110 insertions, 0 deletions

diff --git a/lib/Sema/SemaAttr.cpp b/lib/Sema/SemaAttr.cpp
new file mode 100644
index 0000000000..a3978ac32c
--- /dev/null
+++ b/lib/Sema/SemaAttr.cpp
@@ -0,0 +1,110 @@
+//===--- SemaAttr.cpp - Semantic Analysis for Attributes ------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements semantic analysis for non-trivial attributes.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Sema.h"
+#include "clang/AST/Expr.h"
+using namespace clang;
+
+void Sema::ActOnPragmaPack(PragmaPackKind Kind, IdentifierInfo *Name, 
+                           ExprTy *alignment, SourceLocation PragmaLoc, 
+                           SourceLocation LParenLoc, SourceLocation RParenLoc) {
+  Expr *Alignment = static_cast<Expr *>(alignment);
+
+  // If specified then alignment must be a "small" power of two.
+  unsigned AlignmentVal = 0;
+  if (Alignment) {
+    llvm::APSInt Val;
+    if (!Alignment->isIntegerConstantExpr(Val, Context) ||
+        !Val.isPowerOf2() ||
+        Val.getZExtValue() > 16) {
+      Diag(PragmaLoc, diag::warn_pragma_pack_invalid_alignment);
+      Alignment->Destroy(Context);
+      return; // Ignore
+    }
+
+    AlignmentVal = (unsigned) Val.getZExtValue();
+  }
+
+  switch (Kind) {
+  case Action::PPK_Default: // pack([n])
+    PackContext.setAlignment(AlignmentVal);
+    break;
+
+  case Action::PPK_Show: // pack(show)
+    // Show the current alignment, making sure to show the right value
+    // for the default.
+    AlignmentVal = PackContext.getAlignment();
+    // FIXME: This should come from the target.
+    if (AlignmentVal == 0)
+      AlignmentVal = 8;
+    Diag(PragmaLoc, diag::warn_pragma_pack_show) << AlignmentVal;
+    break;
+
+  case Action::PPK_Push: // pack(push [, id] [, [n])
+    PackContext.push(Name);
+    // Set the new alignment if specified.
+    if (Alignment)
+      PackContext.setAlignment(AlignmentVal);    
+    break;
+
+  case Action::PPK_Pop: // pack(pop [, id] [,  n])
+    // MSDN, C/C++ Preprocessor Reference > Pragma Directives > pack:
+    // "#pragma pack(pop, identifier, n) is undefined"
+    if (Alignment && Name)
+      Diag(PragmaLoc, diag::warn_pragma_pack_pop_identifer_and_alignment);    
+    
+    // Do the pop.
+    if (!PackContext.pop(Name)) {
+      // If a name was specified then failure indicates the name
+      // wasn't found. Otherwise failure indicates the stack was
+      // empty.
+      Diag(PragmaLoc, diag::warn_pragma_pack_pop_failed)
+        << (Name ? "no record matching name" : "stack empty");
+
+      // FIXME: Warn about popping named records as MSVC does.
+    } else {
+      // Pop succeeded, set the new alignment if specified.
+      if (Alignment)
+        PackContext.setAlignment(AlignmentVal);
+    }
+    break;
+
+  default:
+    assert(0 && "Invalid #pragma pack kind.");
+  }
+}
+
+bool PragmaPackStack::pop(IdentifierInfo *Name) {
+  if (Stack.empty())
+    return false;
+
+  // If name is empty just pop top.
+  if (!Name) {
+    Alignment = Stack.back().first;
+    Stack.pop_back();
+    return true;
+  } 
+
+  // Otherwise, find the named record.
+  for (unsigned i = Stack.size(); i != 0; ) {
+    --i;
+    if (Stack[i].second == Name) {
+      // Found it, pop up to and including this record.
+      Alignment = Stack[i].first;
+      Stack.erase(Stack.begin() + i, Stack.end());
+      return true;
+    }
+  }
+
+  return false;
+}