[PATCH] D107394: [AIX] "aligned" attribute does not decrease alignment

[Steven Wan via Phabricator via cfe-commits]

stevewan updated this revision to Diff 363870.
stevewan added a comment.

Fix incomplete diff, please discard last update.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D107394/new/

https://reviews.llvm.org/D107394

Files:
  clang/lib/AST/ASTContext.cpp
  clang/test/Layout/aix-alignof-align-and-pack-attr.cpp
  clang/test/Layout/aix-alignof-align-attr.cpp


Index: clang/test/Layout/aix-alignof-align-attr.cpp
===================================================================
--- /dev/null
+++ clang/test/Layout/aix-alignof-align-attr.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple powerpc-ibm-aix-xcoff -S -emit-llvm -x c++ < %s | \
+// RUN:   FileCheck %s
+
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix-xcoff -S -emit-llvm -x c++ < %s | 
\
+// RUN:   FileCheck %s
+
+struct __attribute__((__aligned__(2))) C {
+  double x;
+} c;
+
+// CHECK: @c = global %struct.C zeroinitializer, align 8
Index: clang/test/Layout/aix-alignof-align-and-pack-attr.cpp
===================================================================
--- /dev/null
+++ clang/test/Layout/aix-alignof-align-and-pack-attr.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple powerpc-ibm-aix-xcoff -S -emit-llvm -x c++ < %s | \
+// RUN:   FileCheck %s
+
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix-xcoff -S -emit-llvm -x c++ < %s | 
\
+// RUN:   FileCheck %s
+
+struct __attribute__((__aligned__(2), packed)) C {
+  double x;
+} c;
+
+// CHECK: @c = global %struct.C zeroinitializer, align 2
Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -2478,11 +2478,16 @@
     return ABIAlign;
 
   if (const auto *RT = T->getAs<RecordType>()) {
-    if (TI.AlignIsRequired || RT->getDecl()->isInvalidDecl())
+    const RecordDecl *RD = RT->getDecl();
+
+    // When used as part of a typedef, or together with a 'packed' attribute,
+    // the 'aligned' attribute can be used to decrease alignment.
+    if ((TI.AlignIsRequired && T->getAs<TypedefType>() != nullptr) ||
+        RD->isInvalidDecl())
       return ABIAlign;
 
     unsigned PreferredAlign = static_cast<unsigned>(
-        toBits(getASTRecordLayout(RT->getDecl()).PreferredAlignment));
+        toBits(getASTRecordLayout(RD).PreferredAlignment));
     assert(PreferredAlign >= ABIAlign &&
            "PreferredAlign should be at least as large as ABIAlign.");
     return PreferredAlign;



Index: clang/test/Layout/aix-alignof-align-attr.cpp
===================================================================
--- /dev/null
+++ clang/test/Layout/aix-alignof-align-attr.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple powerpc-ibm-aix-xcoff -S -emit-llvm -x c++ < %s | \
+// RUN:   FileCheck %s
+
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix-xcoff -S -emit-llvm -x c++ < %s | \
+// RUN:   FileCheck %s
+
+struct __attribute__((__aligned__(2))) C {
+  double x;
+} c;
+
+// CHECK: @c = global %struct.C zeroinitializer, align 8
Index: clang/test/Layout/aix-alignof-align-and-pack-attr.cpp
===================================================================
--- /dev/null
+++ clang/test/Layout/aix-alignof-align-and-pack-attr.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple powerpc-ibm-aix-xcoff -S -emit-llvm -x c++ < %s | \
+// RUN:   FileCheck %s
+
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix-xcoff -S -emit-llvm -x c++ < %s | \
+// RUN:   FileCheck %s
+
+struct __attribute__((__aligned__(2), packed)) C {
+  double x;
+} c;
+
+// CHECK: @c = global %struct.C zeroinitializer, align 2
Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -2478,11 +2478,16 @@
     return ABIAlign;
 
   if (const auto *RT = T->getAs<RecordType>()) {
-    if (TI.AlignIsRequired || RT->getDecl()->isInvalidDecl())
+    const RecordDecl *RD = RT->getDecl();
+
+    // When used as part of a typedef, or together with a 'packed' attribute,
+    // the 'aligned' attribute can be used to decrease alignment.
+    if ((TI.AlignIsRequired && T->getAs<TypedefType>() != nullptr) ||
+        RD->isInvalidDecl())
       return ABIAlign;
 
     unsigned PreferredAlign = static_cast<unsigned>(
-        toBits(getASTRecordLayout(RT->getDecl()).PreferredAlignment));
+        toBits(getASTRecordLayout(RD).PreferredAlignment));
     assert(PreferredAlign >= ABIAlign &&
            "PreferredAlign should be at least as large as ABIAlign.");
     return PreferredAlign;

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