[PATCH] D107522: [PowerPC][AIX] attribute aligned cannot decrease align of a vector var.

[Sean Fertile via Phabricator via llvm-commits]

sfertile created this revision.
sfertile added reviewers: stevewan, Jake-Egan, hubert.reinterpretcast.
Herald added subscribers: shchenz, nemanjai.
Herald added a reviewer: aaron.ballman.
sfertile requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

On AIX an aligned attribute cannot decrease the alignment of a variable when placed on a variable declaration of vector type.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D107522

Files:
  clang/lib/Sema/SemaDeclAttr.cpp
  clang/test/CodeGen/aix-vector-attr-aligned.c
  clang/test/Sema/aix-attr-aligned-vector-typedef.c


Index: clang/test/Sema/aix-attr-aligned-vector-typedef.c
===================================================================
--- /dev/null
+++ clang/test/Sema/aix-attr-aligned-vector-typedef.c
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -triple powerpc64-unknown-aix -target-feature +altivec -target-cpu pwr7 -verify -fsyntax-only %s
+// RUN: %clang_cc1 -triple powerpc-unknown-aix -target-feature +altivec -target-cpu pwr7 -verify -fsyntax-only %s
+
+int escape(vector int*);
+
+typedef vector int __attribute__((aligned(8))) UnderAlignedVI;
+UnderAlignedVI TypedefedGlobal;
+
+int localTypedefed(void) {
+  UnderAlignedVI TypedefedLocal;
+  return escape(&TypedefedLocal); // expected-warning {{passing 8-byte aligned argument to 16-byte aligned parameter 1 of 'escape' may result in an unaligned pointer access}}
+}
Index: clang/test/CodeGen/aix-vector-attr-aligned.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/aix-vector-attr-aligned.c
@@ -0,0 +1,33 @@
+// REQUIRES: powerpc-registered-target
+// RUN: %clang_cc1 -triple powerpc-unknown-aix -target-feature +altivec -target-cpu pwr7 -emit-llvm -o - %s | \
+// RUN:   FileCheck %s
+// RUN: %clang_cc1 -triple powerpc64-unknown-aix -target-feature +altivec -target-cpu pwr7 -emit-llvm -o - %s | \
+// RUN:   FileCheck %s
+
+typedef vector int __attribute__((aligned(8))) UnderAlignedVI;
+
+vector int g32 __attribute__((aligned(32)));
+vector int g8 __attribute__((aligned(8)));
+UnderAlignedVI TypedefedGlobal;
+
+int escape(vector int*);
+
+int local32(void) {
+  vector int l32 __attribute__((aligned(32)));
+  return escape(&l32);
+}
+
+int local8(void) {
+  vector int l8 __attribute__((aligned(8)));
+  return escape(&l8);
+}
+
+// CHECK: @g32 = global <4 x i32> zeroinitializer, align 32
+// CHECK: @g8 = global <4 x i32> zeroinitializer, align 16
+// CHECK: @TypedefedGlobal = global <4 x i32> zeroinitializer, align 8
+
+// CHECK-LABEL: @local32
+// CHECK:         %l32 = alloca <4 x i32>, align 32
+//
+// CHECK-LABEL: @local8
+// CHECK:         %l8 = alloca <4 x i32>, align 16
Index: clang/lib/Sema/SemaDeclAttr.cpp
===================================================================
--- clang/lib/Sema/SemaDeclAttr.cpp
+++ clang/lib/Sema/SemaDeclAttr.cpp
@@ -4060,11 +4060,11 @@
     return;
   }
 
+  const auto *VD = dyn_cast<VarDecl>(D);
   if (Context.getTargetInfo().isTLSSupported()) {
     unsigned MaxTLSAlign =
         Context.toCharUnitsFromBits(Context.getTargetInfo().getMaxTLSAlign())
             .getQuantity();
-    const auto *VD = dyn_cast<VarDecl>(D);
     if (MaxTLSAlign && AlignVal > MaxTLSAlign && VD &&
         VD->getTLSKind() != VarDecl::TLS_None) {
       Diag(VD->getLocation(), diag::err_tls_var_aligned_over_maximum)
@@ -4073,6 +4073,14 @@
     }
   }
 
+  // On AIX, an aligned attribute can not decrease the alignemnt when applied
+  // to a variable declaration with vector type.
+  if (VD && Context.getTargetInfo().getTriple().isOSAIX()) {
+    const Type *Ty = VD->getType().getTypePtr();
+    if (Ty->isVectorType() && AlignVal < 16)
+      return;
+  }
+
   AlignedAttr *AA = ::new (Context) AlignedAttr(Context, CI, true, ICE.get());
   AA->setPackExpansion(IsPackExpansion);
   D->addAttr(AA);


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