[PATCH] D98864: [SystemZ][z/OS] Set maximum value to truncate attribute aligned to for static variables on z/OS target

[Fanbo Meng via Phabricator via cfe-commits]

fanbo-meng created this revision.
fanbo-meng added reviewers: abhina.sreeskantharajan, muiez, Kai, anirudhp, DanielMcIntosh-IBM.
fanbo-meng requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

On z/OS there is a hard limitation on on the maximum requestable alignment in aligned attribute for static variables. We need to truncate values greater than that.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D98864

Files:
  clang/include/clang/Basic/TargetInfo.h
  clang/lib/AST/ASTContext.cpp
  clang/lib/Basic/TargetInfo.cpp
  clang/lib/Basic/Targets/OSTargets.h
  clang/test/CodeGen/SystemZ/zos-alignment.c


Index: clang/test/CodeGen/SystemZ/zos-alignment.c
===================================================================
--- clang/test/CodeGen/SystemZ/zos-alignment.c
+++ clang/test/CodeGen/SystemZ/zos-alignment.c
@@ -1,4 +1,16 @@
-// RUN: %clang_cc1 -emit-llvm-only -triple s390x-none-zos -fdump-record-layouts %s | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm-only -triple s390x-none-zos -fdump-record-layouts %s | FileCheck %s --check-prefix=CHECK
+// RUN: %clang_cc1 -emit-llvm -triple s390x-none-zos %s -o - | FileCheck %s --check-prefix=DECL
+
+static int __attribute__((aligned(32))) v0;
+int __attribute__((aligned(32))) v1;
+typedef int __attribute__((aligned(32))) int32;
+static int32 v2;
+int32 v3;
+int f0() { return v0 + v1 + v2 + v3; }
+// DECL:      @v0 {{.*}} align 16
+// DECL-NEXT: @v1 {{.*}} align 32
+// DECL-NEXT: @v2 {{.*}} align 16
+// DECL-NEXT: @v3 {{.*}} align 32
 
 struct s0 {
   short a:3;
Index: clang/lib/Basic/Targets/OSTargets.h
===================================================================
--- clang/lib/Basic/Targets/OSTargets.h
+++ clang/lib/Basic/Targets/OSTargets.h
@@ -788,6 +788,7 @@
   ZOSTargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
       : OSTargetInfo<Target>(Triple, Opts) {
     this->WCharType = TargetInfo::UnsignedInt;
+    this->MaxAlignedAttribute = 128;
     this->UseBitFieldTypeAlignment = false;
     this->UseZeroLengthBitfieldAlignment = true;
     this->ZeroLengthBitfieldBoundary = 32;
Index: clang/lib/Basic/TargetInfo.cpp
===================================================================
--- clang/lib/Basic/TargetInfo.cpp
+++ clang/lib/Basic/TargetInfo.cpp
@@ -106,6 +106,7 @@
   UseZeroLengthBitfieldAlignment = false;
   UseExplicitBitFieldAlignment = true;
   ZeroLengthBitfieldBoundary = 0;
+  MaxAlignedAttribute = 0;
   HalfFormat = &llvm::APFloat::IEEEhalf();
   FloatFormat = &llvm::APFloat::IEEEsingle();
   DoubleFormat = &llvm::APFloat::IEEEdouble();
Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -1783,6 +1783,13 @@
     }
   }
 
+  // Some targets have hard limitation on the maximum requestable alignment in
+  // aligned attribute for static variables.
+  const unsigned MaxAlignedAttr = getTargetInfo().getMaxAlignedAttribute();
+  const auto *VD = dyn_cast<VarDecl>(D);
+  if (MaxAlignedAttr && VD && VD->getStorageClass() == SC_Static)
+    Align = std::min(Align, MaxAlignedAttr);
+
   return toCharUnitsFromBits(Align);
 }
 
Index: clang/include/clang/Basic/TargetInfo.h
===================================================================
--- clang/include/clang/Basic/TargetInfo.h
+++ clang/include/clang/Basic/TargetInfo.h
@@ -161,6 +161,10 @@
   /// If non-zero, specifies a fixed alignment value for bitfields that follow
   /// zero length bitfield, regardless of the zero length bitfield type.
   unsigned ZeroLengthBitfieldBoundary;
+
+  /// If non-zero, specifies a maximum alignment to truncate alignment
+  /// specified in the aligned attribute of a static variable to this value.
+  unsigned MaxAlignedAttribute;
 };
 
 /// OpenCL type kinds.
@@ -774,6 +778,12 @@
     return ZeroLengthBitfieldBoundary;
   }
 
+  /// Get the maximum alignment in bits for a static variable with
+  /// aligned attribute.
+  unsigned getMaxAlignedAttribute() const {
+    return MaxAlignedAttribute;
+  }
+
   /// Check whether explicit bitfield alignment attributes should be
   //  honored, as in "__attribute__((aligned(2))) int b : 1;".
   bool useExplicitBitFieldAlignment() const {


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