[X86] Fix stack alignment for MCU target (Clang part)

[anadolskiy]

Summary

This patch fixes stack alignments for MCU (should be aligned to 4 bytes)
LLVM part: http://reviews.llvm.org/D15646

[anadolskiy]

ping

[rjmccall]

tools/clang/lib/AST/ASTContext.cpp

1902 ↗

(On Diff #43244)

Please turn this into a method or flag on TargetInfo. I suggest

bool AllowLargerPreferredTypeAlignment;

[anadolskiy]

Thanks for review John. Addressed your comment.

[rjmccall]

LGTM, thanks.

cfe/trunk/include/clang/Basic/TargetInfo.h

public:
   }
 
   /// Controls if __builtin_longjmp / __builtin_setjmp can be lowered to
   /// llvm.eh.sjlj.longjmp / llvm.eh.sjlj.setjmp.
   virtual bool hasSjLjLowering() const {
     return false;
   }
 
+  /// \brief Whether target allows to overalign ABI-specified prefered alignment
+  virtual bool allowsLargerPreferedTypeAlignment() const { return true; }
+
 protected:
   virtual uint64_t getPointerWidthV(unsigned AddrSpace) const {
     return PointerWidth;
   }
   virtual uint64_t getPointerAlignV(unsigned AddrSpace) const {
     return PointerAlign;
   }
   virtual enum IntType getPtrDiffTypeV(unsigned AddrSpace) const {

cfe/trunk/lib/AST/ASTContext.cpp

unsigned ASTContext::getPreferredTypeAlign(const Type *T) const {
   unsigned ABIAlign = TI.Align;
 
   T = T->getBaseElementTypeUnsafe();
 
   // The preferred alignment of member pointers is that of a pointer.
   if (T->isMemberPointerType())
     return getPreferredTypeAlign(getPointerDiffType().getTypePtr());
 
-  if (Target->getTriple().getArch() == llvm::Triple::xcore)
-    return ABIAlign;  // Never overalign on XCore.
+  if (!Target->allowsLargerPreferedTypeAlignment())
+    return ABIAlign;
 
   // Double and long long should be naturally aligned if possible.
   if (const ComplexType *CT = T->getAs<ComplexType>())
     T = CT->getElementType().getTypePtr();
   if (const EnumType *ET = T->getAs<EnumType>())
     T = ET->getDecl()->getIntegerType().getTypePtr();
   if (T->isSpecificBuiltinType(BuiltinType::Double) ||
       T->isSpecificBuiltinType(BuiltinType::LongLong) ||

cfe/trunk/lib/Basic/Targets.cpp

 
 // x86-32 Windows Visual Studio target
 class MicrosoftX86_32TargetInfo : public WindowsX86_32TargetInfo {
 public:
   MicrosoftX86_32TargetInfo(const llvm::Triple &Triple)
       : WindowsX86_32TargetInfo(Triple) {
     LongDoubleWidth = LongDoubleAlign = 64;
     LongDoubleFormat = &llvm::APFloat::IEEEdouble;
+    DataLayoutString =
+        "e-m:e-p:32:32-i64:32-f64:32-f128:32-n8:16:32-a:0:32-S32";
   }
   void getTargetDefines(const LangOptions &Opts,
                         MacroBuilder &Builder) const override {
     WindowsX86_32TargetInfo::getTargetDefines(Opts, Builder);
     WindowsX86_32TargetInfo::getVisualStudioDefines(Opts, Builder);
     // The value of the following reflects processor type.
     // 300=386, 400=486, 500=Pentium, 600=Blend (default)
     // We lost the original triple, so we use the default.
public:
   }
 
   void getTargetDefines(const LangOptions &Opts,
                         MacroBuilder &Builder) const override {
     X86_32TargetInfo::getTargetDefines(Opts, Builder);
     Builder.defineMacro("__iamcu");
     Builder.defineMacro("__iamcu__");
   }
+
+  bool allowsLargerPreferedTypeAlignment() const override {
+    return false;
+  }
 };
 
 // RTEMS Target
 template<typename Target>
 class RTEMSTargetInfo : public OSTargetInfo<Target> {
 protected:
   void getOSDefines(const LangOptions &Opts, const llvm::Triple &Triple,
                     MacroBuilder &Builder) const override {
public:
   bool validateAsmConstraint(const char *&Name,
                              TargetInfo::ConstraintInfo &Info) const override {
     return false;
   }
   int getEHDataRegisterNumber(unsigned RegNo) const override {
     // R0=ExceptionPointerRegister R1=ExceptionSelectorRegister
     return (RegNo < 2)? RegNo : -1;
   }
+  bool allowsLargerPreferedTypeAlignment() const override {
+    return false;
+  }
 };
 
 const Builtin::Info XCoreTargetInfo::BuiltinInfo[] = {
 #define BUILTIN(ID, TYPE, ATTRS) \
   { #ID, TYPE, ATTRS, nullptr, ALL_LANGUAGES, nullptr },
 #define LIBBUILTIN(ID, TYPE, ATTRS, HEADER) \
   { #ID, TYPE, ATTRS, HEADER, ALL_LANGUAGES, nullptr },
 #include "clang/Basic/BuiltinsXCore.def"

cfe/trunk/test/CodeGen/iamcu-abi.c

+// RUN: %clang_cc1 -triple i386-pc-elfiamcu -emit-llvm -o - %s | FileCheck %s
+
+// CHECK: target datalayout = "e-m:e-p:32:32-i64:32-f64:32-f128:32-n8:16:32-a:0:32-S32"
+// CHECK: target triple = "i386-pc-elfiamcu"
+
+
+void food(double *d);
+void fooll(long long *ll);
+void fooull(unsigned long long *ull);
+void foold(long double *ld);
+
+// CHECK-LABEL: define void @testdouble()
+// CHECK: alloca double, align 4
+void testdouble() {
+  double d = 2.0;
+  food(&d);
+}
+
+// CHECK-LABEL: define void @testlonglong()
+// CHECK: alloca i64, align 4
+void testlonglong() {
+  long long ll = 2;
+  fooll(&ll);
+}
+
+// CHECK-LABEL: define void @testunsignedlonglong()
+// CHECK: alloca i64, align 4
+void testunsignedlonglong() {
+  unsigned long long ull = 2;
+  fooull(&ull); 
+}
+
+// CHECK-LABEL: define void @testlongdouble()
+// CHECK: alloca double, align 4
+void testlongdouble() {
+  long double ld = 2.0;
+  foold(&ld);
+}