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Fix __alignof__ of global variables on SystemZ 

SystemZ prefers to align all global variables to two bytes, which is
implemented by setting the TargetInfo member MinGlobalAlign.

However, for compatibility with existing compilers this should *not*
change the ABI alignment value as retrieved via __alignof__, which
it currently does.

This patch fixes the issue by having ASTContext::getDeclAlign ignore
the MinGlobalAlign setting in the ForAlignof case.

Since SystemZ is the only platform setting MinGlobalAlign, this should
cause no change for any other target.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@235395 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Ulrich Weigand 2015-04-21 17:26:18 +00:00
parent 91e509234e
commit 5dfb48c2d4
3 changed files with 32 additions and 1 deletions
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2
lib/AST/ASTContext.cpp
View File

@ -1335,7 +1335,7 @@ CharUnits ASTContext::getDeclAlign(const Decl *D, bool ForAlignof) const {
}
Align = std::max(Align, getPreferredTypeAlign(T.getTypePtr()));
if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
if (VD->hasGlobalStorage())
if (VD->hasGlobalStorage() && !ForAlignof)
Align = std::max(Align, getTargetInfo().getMinGlobalAlign());
}
}

14
test/CodeGen/align-systemz.c Normal file
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@ -0,0 +1,14 @@
// RUN: %clang_cc1 -triple s390x-linux-gnu -emit-llvm %s -o - | FileCheck %s
// SystemZ prefers to align all global variables to two bytes.
struct test {
signed char a;
};
char c;
// CHECK-DAG: @c = common global i8 0, align 2
struct test s;
// CHECK-DAG: @s = common global %struct.test zeroinitializer, align 2

17
test/Sema/align-systemz.c Normal file
View File

@ -0,0 +1,17 @@
// RUN: %clang_cc1 -triple s390x-linux-gnu -fsyntax-only -verify %s
// expected-no-diagnostics
// SystemZ prefers to align all global variables to two bytes,
// but this should *not* be reflected in the ABI alignment as
// retrieved via __alignof__.
struct test {
signed char a;
};
char c;
struct test s;
int chk1[__alignof__(c) == 1 ? 1 : -1];
int chk2[__alignof__(s) == 1 ? 1 : -1];