[PATCH] D107506: [PowerPC][AIX] Warn when using pragma align(packed) on AIX.

[Sean Fertile via Phabricator via cfe-commits]

sfertile created this revision.
sfertile added reviewers: stevewan, Jake-Egan, cebowleratibm.
sfertile added a project: PowerPC.
Herald added subscribers: shchenz, nemanjai.
sfertile requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

With xlc and xlC pragma align(packed) will pack bitfields the same way as pragma align(bit_packed). xlclang, xlclang++ and clang will pack bitfields the same way as pragma pack(1). Issue a warning when source code using pragma align(packed)  to alert the user it may not be compatible with xlc/xlC.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D107506

Files:
  clang/include/clang/Basic/DiagnosticSemaKinds.td
  clang/lib/Sema/SemaAttr.cpp
  clang/test/Sema/aix-pragma-align-packed-warn.c
  clang/test/Sema/aix-pragma-pack-and-align.c


Index: clang/test/Sema/aix-pragma-pack-and-align.c
===================================================================
--- clang/test/Sema/aix-pragma-pack-and-align.c
+++ clang/test/Sema/aix-pragma-pack-and-align.c
@@ -170,7 +170,7 @@
 } // namespace test7
 
 namespace test8 {
-#pragma align(packed)
+#pragma align(packed) // expected-warning {{#pragma align(packed) may not be compatible with objects generated with AIX XL C/C++}}
 #pragma pack(2)
 #pragma pack(show) // expected-warning {{value of #pragma pack(show) == 2}}
 struct A {
Index: clang/test/Sema/aix-pragma-align-packed-warn.c
===================================================================
--- /dev/null
+++ clang/test/Sema/aix-pragma-align-packed-warn.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix-xcoff  -fxl-pragma-pack -verify -fsyntax-only %s
+// RUN: %clang_cc1 -triple powerpc-ibm-aix-xcoff  -fxl-pragma-pack -verify -fsyntax-only %s
+
+#pragma align(packed) // expected-warning {{#pragma align(packed) may not be compatible with objects generated with AIX XL C/C++}}
+struct A {
+  int a : 8;
+  int   : 0;
+  short s;
+};
+#pragma align(reset)
Index: clang/lib/Sema/SemaAttr.cpp
===================================================================
--- clang/lib/Sema/SemaAttr.cpp
+++ clang/lib/Sema/SemaAttr.cpp
@@ -234,6 +234,8 @@
     // Note that '#pragma options align=packed' is not equivalent to attribute
     // packed, it has a different precedence relative to attribute aligned.
   case POAK_Packed:
+    if (this->Context.getTargetInfo().getTriple().isOSAIX())
+      Diag(PragmaLoc, diag::warn_pragma_align_not_xl_compatible);
     Action = Sema::PSK_Push_Set;
     ModeVal = AlignPackInfo::Packed;
     break;
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -913,6 +913,9 @@
   InGroup<IgnoredPragmas>;
 def err_pragma_options_align_mac68k_target_unsupported : Error<
   "mac68k alignment pragma is not supported on this target">;
+def warn_pragma_align_not_xl_compatible : Warning<
+  "#pragma align(packed) may not be compatible with objects generated with AIX XL C/C++">,
+  InGroup<AIXCompat>;
 def warn_pragma_pack_invalid_alignment : Warning<
   "expected #pragma pack parameter to be '1', '2', '4', '8', or '16'">,
   InGroup<IgnoredPragmas>;


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