[AArch64] Use MCAsmInfoMicrosoft and MCAsmInfoGNUCOFF as base classes

This matches the structure used on X86 and ARM. This requires
a little bit of duplication of the parts that are equal in both
AArch64 COFF variants though.

Before SVN r335286, these classes didn't add anything that MCAsmInfoCOFF
didn't, but now they do.

This makes AArch64 match X86 in how comdat is used for float constants
for MinGW.

Differential Revision: https://reviews.llvm.org/D49637

llvm-svn: 337755
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp
index 12b5a27..ebb4912 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp
@@ -101,7 +101,7 @@
   HasIdentDirective = true;
 }
 
-AArch64MCAsmInfoCOFF::AArch64MCAsmInfoCOFF() {
+AArch64MCAsmInfoMicrosoftCOFF::AArch64MCAsmInfoMicrosoftCOFF() {
   PrivateGlobalPrefix = ".L";
   PrivateLabelPrefix = ".L";
 
@@ -112,14 +112,23 @@
   AlignmentIsInBytes = false;
   SupportsDebugInformation = true;
   CodePointerSize = 8;
-}
 
-AArch64MCAsmInfoMicrosoftCOFF::AArch64MCAsmInfoMicrosoftCOFF() {
   CommentString = ";";
   ExceptionsType = ExceptionHandling::WinEH;
 }
 
 AArch64MCAsmInfoGNUCOFF::AArch64MCAsmInfoGNUCOFF() {
+  PrivateGlobalPrefix = ".L";
+  PrivateLabelPrefix = ".L";
+
+  Data16bitsDirective = "\t.hword\t";
+  Data32bitsDirective = "\t.word\t";
+  Data64bitsDirective = "\t.xword\t";
+
+  AlignmentIsInBytes = false;
+  SupportsDebugInformation = true;
+  CodePointerSize = 8;
+
   CommentString = "//";
   ExceptionsType = ExceptionHandling::DwarfCFI;
 }
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.h b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.h
index afde87b..e8570b1 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.h
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.h
@@ -34,15 +34,11 @@
   explicit AArch64MCAsmInfoELF(const Triple &T);
 };
 
-struct AArch64MCAsmInfoCOFF : public MCAsmInfoCOFF {
-  explicit AArch64MCAsmInfoCOFF();
-};
-
-struct AArch64MCAsmInfoMicrosoftCOFF : public AArch64MCAsmInfoCOFF {
+struct AArch64MCAsmInfoMicrosoftCOFF : public MCAsmInfoMicrosoft {
   explicit AArch64MCAsmInfoMicrosoftCOFF();
 };
 
-struct AArch64MCAsmInfoGNUCOFF : public AArch64MCAsmInfoCOFF {
+struct AArch64MCAsmInfoGNUCOFF : public MCAsmInfoGNUCOFF {
   explicit AArch64MCAsmInfoGNUCOFF();
 };
 
diff --git a/llvm/test/CodeGen/AArch64/win_cst_pool.ll b/llvm/test/CodeGen/AArch64/win_cst_pool.ll
new file mode 100644
index 0000000..049e252
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/win_cst_pool.ll
@@ -0,0 +1,13 @@
+; RUN: llc < %s -mtriple=aarch64-win32-gnu | FileCheck -check-prefix=MINGW %s
+
+define double @double() {
+  ret double 0x0000000000800000
+}
+; MINGW:              .section        .rdata,"dr"
+; MINGW-NEXT:         .p2align  3
+; MINGW-NEXT: [[LABEL:\.LC.*]]:
+; MINGW-NEXT:         .xword   8388608
+; MINGW:      double:
+; MINGW:               adrp    x8, [[LABEL]]
+; MINGW-NEXT:          ldr     d0, [x8, [[LABEL]]]
+; MINGW-NEXT:          ret