[clang] 66225db - [PowerPC][AIX] Add warning when alignment is incompatible with XL
Zarko Todorovski via cfe-commits
cfe-commits at lists.llvm.org
Fri Jul 16 04:52:54 PDT 2021
Author: Zarko Todorovski
Date: 2021-07-16T07:52:47-04:00
New Revision: 66225db98d832bec75ffb96298107c015b0035f0
URL: https://github.com/llvm/llvm-project/commit/66225db98d832bec75ffb96298107c015b0035f0
DIFF: https://github.com/llvm/llvm-project/commit/66225db98d832bec75ffb96298107c015b0035f0.diff
LOG: [PowerPC][AIX] Add warning when alignment is incompatible with XL
https://reviews.llvm.org/D105659 implements ByVal handling in llc but
some cases are not compatible with existing XL compiler on AIX. Adding
a clang warning for such cases.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D105660
Added:
clang/test/Sema/aix-attr-align.c
Modified:
clang/include/clang/Basic/DiagnosticGroups.td
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaDeclAttr.cpp
Removed:
################################################################################
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index 18097cfcfffe..eb1b5641bfdf 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -1083,6 +1083,9 @@ def GNU : DiagGroup<"gnu", [GNUAlignofExpression, GNUAnonymousStruct,
// A warning group for warnings about code that clang accepts but gcc doesn't.
def GccCompat : DiagGroup<"gcc-compat">;
+// A warning group for warnings about code that may be incompatible on AIX.
+def AIXCompat : DiagGroup<"aix-compat">;
+
// Warnings for Microsoft extensions.
def MicrosoftCharize : DiagGroup<"microsoft-charize">;
def MicrosoftDrectveSection : DiagGroup<"microsoft-drectve-section">;
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 779093977da8..823a36a597c5 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3254,6 +3254,10 @@ def warn_assume_aligned_too_great
: Warning<"requested alignment must be %0 bytes or smaller; maximum "
"alignment assumed">,
InGroup<DiagGroup<"builtin-assume-aligned-alignment">>;
+def warn_not_xl_compatible
+ : Warning<"requesting an alignment of 16 bytes or greater for struct"
+ " members is not binary compatible with AIX XL 16.1 and older">,
+ InGroup<AIXCompat>;
def warn_redeclaration_without_attribute_prev_attribute_ignored : Warning<
"%q0 redeclared without %1 attribute: previous %1 ignored">,
InGroup<MicrosoftInconsistentDllImport>;
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 3586ad323b8e..9aac9d215644 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -3953,6 +3953,12 @@ void Sema::AddAlignedAttr(Decl *D, const AttributeCommonInfo &CI, Expr *E,
return;
uint64_t AlignVal = Alignment.getZExtValue();
+ // 16 byte ByVal alignment not due to a vector member is not honoured by XL
+ // on AIX. Emit a warning here that users are generating binary incompatible
+ // code to be safe.
+ if (AlignVal >= 16 && isa<FieldDecl>(D) &&
+ Context.getTargetInfo().getTriple().isOSAIX())
+ Diag(AttrLoc, diag::warn_not_xl_compatible) << E->getSourceRange();
// C++11 [dcl.align]p2:
// -- if the constant expression evaluates to zero, the alignment
diff --git a/clang/test/Sema/aix-attr-align.c b/clang/test/Sema/aix-attr-align.c
new file mode 100644
index 000000000000..ac70aab66900
--- /dev/null
+++ b/clang/test/Sema/aix-attr-align.c
@@ -0,0 +1,22 @@
+// off-no-diagnostics
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix-xcoff -verify -fsyntax-only %s
+// RUN: %clang_cc1 -triple powerpc-ibm-aix-xcoff -verify -fsyntax-only %s
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix-xcoff -verify=off -Wno-aix-compat -fsyntax-only %s
+// RUN: %clang_cc1 -triple powerpc-ibm-aix-xcoff -verify=off -Wno-aix-compat -fsyntax-only %s
+// RUN: %clang_cc1 -triple powerpc64le-unknown-linux -verify=off -fsyntax-only %s
+
+struct S {
+ int a[8] __attribute__((aligned(8))); // no-warning
+};
+
+struct T {
+ int a[4] __attribute__((aligned(16))); // expected-warning {{requesting an alignment of 16 bytes or greater for struct members is not binary compatible with AIX XL 16.1 and older}}
+};
+
+struct U {
+ int a[2] __attribute__((aligned(32))); // expected-warning {{requesting an alignment of 16 bytes or greater for struct members is not binary compatible with AIX XL 16.1 and older}}
+};
+
+int a[8] __attribute__((aligned(8))); // no-warning
+int b[4] __attribute__((aligned(16))); // no-warning
+int c[2] __attribute__((aligned(32))); // no-warning
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