[SystemZ] Make 128 bit integers be aligned to 8 bytes.

The SystemZ ABI says that 128 bit integers should be aligned to only 8 bytes.

Reviewed By: Ulrich Weigand, Nikita Popov

Differential Revision: https://reviews.llvm.org/D130900

Author: JonPsson

clang/include/clang/Basic/TargetInfo.h

@@ -78,6 +78,7 @@ struct TransferrableTargetInfo {
   unsigned char LargeArrayMinWidth, LargeArrayAlign;
   unsigned char LongWidth, LongAlign;
   unsigned char LongLongWidth, LongLongAlign;
+  unsigned char Int128Align;
 
   // Fixed point bit widths
   unsigned char ShortAccumWidth, ShortAccumAlign;
@@ -470,6 +471,9 @@ class TargetInfo : public virtual TransferrableTargetInfo,
   unsigned getLongLongWidth() const { return LongLongWidth; }
   unsigned getLongLongAlign() const { return LongLongAlign; }
 
+  /// getInt128Align() - Returns the alignment of Int128.
+  unsigned getInt128Align() const { return Int128Align; }
+
   /// getShortAccumWidth/Align - Return the size of 'signed short _Accum' and
   /// 'unsigned short _Accum' for this target, in bits.
   unsigned getShortAccumWidth() const { return ShortAccumWidth; }

clang/lib/AST/ASTContext.cpp

@@ -2082,7 +2082,7 @@ TypeInfo ASTContext::getTypeInfoImpl(const Type *T) const {
     case BuiltinType::Int128:
     case BuiltinType::UInt128:
       Width = 128;
-      Align = 128; // int128_t is 128-bit aligned on all targets.
+      Align = Target->getInt128Align();
       break;
     case BuiltinType::ShortAccum:
     case BuiltinType::UShortAccum:

clang/lib/Basic/TargetInfo.cpp

@@ -45,6 +45,7 @@ TargetInfo::TargetInfo(const llvm::Triple &T) : Triple(T) {
   IntWidth = IntAlign = 32;
   LongWidth = LongAlign = 32;
   LongLongWidth = LongLongAlign = 64;
+  Int128Align = 128;
 
   // Fixed point default bit widths
   ShortAccumWidth = ShortAccumAlign = 16;

clang/lib/Basic/Targets/SystemZ.h

@@ -40,6 +40,7 @@ class LLVM_LIBRARY_VISIBILITY SystemZTargetInfo : public TargetInfo {
     TLSSupported = true;
     IntWidth = IntAlign = 32;
     LongWidth = LongLongWidth = LongAlign = LongLongAlign = 64;
+    Int128Align = 64;
     PointerWidth = PointerAlign = 64;
     LongDoubleWidth = 128;
     LongDoubleAlign = 64;

clang/test/CodeGen/SystemZ/align-systemz.c

@@ -26,6 +26,14 @@ void func (void)
 }
 
 
+// The SystemZ ABI aligns __int128_t to only eight bytes.
+
+struct S_int128 {  __int128_t B; } Obj_I128;
+__int128_t GlobI128;
+// CHECK: @Obj_I128 = global %struct.S_int128 zeroinitializer, align 8
+// CHECK: @GlobI128 = global i128 0, align 8
+
+
 // Alignment should be respected for coerced argument loads
 
 struct arg { long y __attribute__((packed, aligned(4))); };
@@ -40,4 +48,3 @@ void test (void)
 
 // CHECK-LABEL: @test
 // CHECK: load i64, i64* getelementptr inbounds (%struct.arg, %struct.arg* @x, i32 0, i32 0), align 4
-

clang/test/CodeGen/SystemZ/systemz-abi.c

@@ -43,7 +43,7 @@ long long pass_longlong(long long arg) { return arg; }
 // CHECK-LABEL: define{{.*}} i64 @pass_longlong(i64 %{{.*}})
 
 __int128 pass_int128(__int128 arg) { return arg; }
-// CHECK-LABEL: define{{.*}} void @pass_int128(i128* noalias sret(i128) align 16 %{{.*}}, i128* %0)
+// CHECK-LABEL: define{{.*}} void @pass_int128(i128* noalias sret(i128) align 8 %{{.*}}, i128* %0)
 
 float pass_float(float arg) { return arg; }
 // CHECK-LABEL: define{{.*}} float @pass_float(float %{{.*}})

clang/test/CodeGen/SystemZ/zos-alignment.c

@@ -160,6 +160,13 @@ struct s11 {
 // CHECK-NEXT:         8 |   char b
 // CHECK-NEXT:           | [sizeof=16, align=8]
 
+struct s12 {
+  __int128_t a;
+} S12;
+// CHECK:              0 | struct s12
+// CHECK-NEXT:         0 |   __int128_t a
+// CHECK-NEXT:           | [sizeof=16, align=8]
+
 union u0 {
   unsigned short d1 __attribute__((packed));
   int d2 : 10;

llvm/test/CodeGen/SystemZ/unaligned-02.ll

@@ -0,0 +1,13 @@
+; Check that an unaligned i128 access get the correct alignment added.
+;
+; RUN: llc < %s -mtriple=s390x-linux-gnu -stop-after=pre-isel-intrinsic-lowering \
+; RUN:   | FileCheck %s
+
+define void @f1(ptr %ptr) {
+; CHECK:       define void @f1(ptr %ptr) {
+; CHECK-NEXT:    store i128 0, ptr %ptr, align 8
+; CHECK-NEXT:    ret void
+; CHECK-NEXT:  }
+  store i128 0, ptr %ptr
+  ret void
+}