[AArch64] Change the preferred alignment for char and short to word alignment.

The commit reinstates r273279, which was informally approved.

Original Review: http://reviews.llvm.org/D21414

This reverts commit ca632c9.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274790 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Chad Rosier

lib/Target/AArch64/AArch64TargetMachine.cpp

@@ -133,8 +133,8 @@ static std::string computeDataLayout(const Triple &TT, bool LittleEndian) {
   if (TT.isOSBinFormatMachO())
     return "e-m:o-i64:64-i128:128-n32:64-S128";
   if (LittleEndian)
-    return "e-m:e-i64:64-i128:128-n32:64-S128";
-  return "E-m:e-i64:64-i128:128-n32:64-S128";
+    return "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128";
+  return "E-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128";
 }
 
 // Helper function to set up the defaults for reciprocals.

test/CodeGen/AArch64/preferred-alignment.ll

@@ -0,0 +1,28 @@
+; RUN: llc -mtriple=aarch64 -O0 < %s | FileCheck %s
+
+; Function Attrs: nounwind
+define i32 @foo() #0 {
+entry:
+  %c = alloca i8, align 1
+; CHECK:	add	x0, sp, #12
+  %s = alloca i16, align 2
+; CHECK-NEXT:	add	x1, sp, #8
+  %i = alloca i32, align 4
+; CHECK-NEXT:	add	x2, sp, #4
+  %call = call i32 @bar(i8* %c, i16* %s, i32* %i)
+  %0 = load i8, i8* %c, align 1
+  %conv = zext i8 %0 to i32
+  %add = add nsw i32 %call, %conv
+  %1 = load i16, i16* %s, align 2
+  %conv1 = sext i16 %1 to i32
+  %add2 = add nsw i32 %add, %conv1
+  %2 = load i32, i32* %i, align 4
+  %add3 = add nsw i32 %add2, %2
+  ret i32 %add3
+}
+
+declare i32 @bar(i8*, i16*, i32*) #1
+
+attributes #0 = { nounwind "no-frame-pointer-elim"="false" }
+attributes #1 = { "no-frame-pointer-elim"="false" }
+