PE/COFF: add support to import functions in ARM NT

This is necessary to support linking a basic program which references symbols
outside of the module itself.  Add the import thunk for ARM NT style imports.
This allows us to create the reference.  However, it is still insufficient to
generate executables that will run due to base relocations not being emitted for
the import.

llvm-svn: 225428

5 files changed, 117 insertions, 7 deletions

diff --git a/lld/lib/ReaderWriter/PECOFF/ReaderImportHeader.cpp b/lld/lib/ReaderWriter/PECOFF/ReaderImportHeader.cpp
index 6c80a146c77..dc158cd4f93 100644
--- a/lld/lib/ReaderWriter/PECOFF/ReaderImportHeader.cpp
+++ b/lld/lib/ReaderWriter/PECOFF/ReaderImportHeader.cpp
@@ -154,10 +154,18 @@ const uint8_t FuncAtomContentX86[] = {
     0xcc, 0xcc                          // INT 3; INT 3
 };
 
+const uint8_t FuncAtomContentARMNT[] = {
+  0x40, 0xf2, 0x00, 0x0c,               // mov.w ip, #0
+  0xc0, 0xf2, 0x00, 0x0c,               // mov.t ip, #0
+  0xdc, 0xf8, 0x00, 0xf0,               // ldr.w pc, [ip]
+};
+
 static void setJumpInstTarget(COFFLinkerInternalAtom *src, const Atom *dst,
                               int off, MachineTypes machine) {
   COFFReference *ref;
+
   switch (machine) {
+  default: llvm::report_fatal_error("unsupported machine type");
   case llvm::COFF::IMAGE_FILE_MACHINE_I386:
     ref = new COFFReference(dst, off, llvm::COFF::IMAGE_REL_I386_DIR32,
                             Reference::KindArch::x86);
@@ -166,9 +174,12 @@ static void setJumpInstTarget(COFFLinkerInternalAtom *src, const Atom *dst,
     ref = new COFFReference(dst, off, llvm::COFF::IMAGE_REL_AMD64_REL32,
                             Reference::KindArch::x86_64);
     break;
-  default:
-    llvm::report_fatal_error("unsupported machine type");
+  case llvm::COFF::IMAGE_FILE_MACHINE_ARMNT:
+    ref = new COFFReference(dst, off, llvm::COFF::IMAGE_REL_ARM_MOV32T,
+                            Reference::KindArch::ARM);
+    break;
   }
+
   src->addReference(std::unique_ptr<COFFReference>(ref));
 }
 
@@ -177,9 +188,22 @@ class FuncAtom : public COFFLinkerInternalAtom {
 public:
   FuncAtom(const File &file, StringRef symbolName,
            const COFFSharedLibraryAtom *impAtom, MachineTypes machine)
-      : COFFLinkerInternalAtom(file, /*oridnal*/ 0, createContent(),
+      : COFFLinkerInternalAtom(file, /*oridnal*/ 0, createContent(machine),
                                symbolName) {
-    setJumpInstTarget(this, impAtom, 2, machine);
+    size_t Offset;
+
+    switch (machine) {
+    default: llvm::report_fatal_error("unsupported machine type");
+    case llvm::COFF::IMAGE_FILE_MACHINE_I386:
+    case llvm::COFF::IMAGE_FILE_MACHINE_AMD64:
+      Offset = 2;
+      break;
+    case llvm::COFF::IMAGE_FILE_MACHINE_ARMNT:
+      Offset = 0;
+      break;
+    }
+
+    setJumpInstTarget(this, impAtom, Offset, machine);
   }
 
   uint64_t ordinal() const override { return 0; }
@@ -189,9 +213,24 @@ public:
   ContentPermissions permissions() const override { return permR_X; }
 
 private:
-  std::vector<uint8_t> createContent() const {
-    return std::vector<uint8_t>(
-        FuncAtomContentX86, FuncAtomContentX86 + sizeof(FuncAtomContentX86));
+  std::vector<uint8_t> createContent(MachineTypes machine) const {
+    const uint8_t *Data;
+    size_t Size;
+
+    switch (machine) {
+    default: llvm::report_fatal_error("unsupported machine type");
+    case llvm::COFF::IMAGE_FILE_MACHINE_I386:
+    case llvm::COFF::IMAGE_FILE_MACHINE_AMD64:
+      Data = FuncAtomContentX86;
+      Size = sizeof(FuncAtomContentX86);
+      break;
+    case llvm::COFF::IMAGE_FILE_MACHINE_ARMNT:
+      Data = FuncAtomContentARMNT;
+      Size = sizeof(FuncAtomContentARMNT);
+      break;
+    }
+
+    return std::vector<uint8_t>(Data, Data + Size);
   }
 };
 
diff --git a/lld/test/pecoff/Inputs/armnt-import.obj.yaml b/lld/test/pecoff/Inputs/armnt-import.obj.yaml
new file mode 100644
index 00000000000..08876eeb0d4
--- /dev/null
+++ b/lld/test/pecoff/Inputs/armnt-import.obj.yaml
@@ -0,0 +1,39 @@
+---
+header:
+  Machine:         IMAGE_FILE_MACHINE_ARMNT
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_PURGEABLE, IMAGE_SCN_MEM_16BIT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       4
+    SectionData:     40F20000C0F2000000680047
+    Relocations:
+      - VirtualAddress:  0
+        SymbolName:      __imp_function
+        Type:            17
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          12
+      NumberOfRelocations: 1
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          1
+  - Name:            mainCRTStartup
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            __imp_function
+    Value:           0
+    SectionNumber:   0
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...
diff --git a/lld/test/pecoff/Inputs/armnt-import.s b/lld/test/pecoff/Inputs/armnt-import.s
new file mode 100644
index 00000000000..2790d0edc8d
--- /dev/null
+++ b/lld/test/pecoff/Inputs/armnt-import.s
@@ -0,0 +1,21 @@
+
+# void __declspec(dllimport) function(void);
+# int mainCRTStartup(void) { return function(); }
+
+	.syntax unified
+	.thumb
+	.text
+
+	.def mainCRTStartup
+		.scl 2
+		.type 32
+	.endef
+	.global mainCRTStartup
+	.align 2
+	.thumb_func
+mainCRTStartup:
+	movw r0, :lower16:__imp_function
+	movt r0, :upper16:__imp_function
+	ldr r0, [r0]
+	bx r0
+
diff --git a/lld/test/pecoff/Inputs/library.lib b/lld/test/pecoff/Inputs/library.lib
new file mode 100755
index 00000000000..2f4207d7983
--- /dev/null
+++ b/lld/test/pecoff/Inputs/library.lib
diff --git a/lld/test/pecoff/armnt-imports.test b/lld/test/pecoff/armnt-imports.test
new file mode 100644
index 00000000000..596270909c5
--- /dev/null
+++ b/lld/test/pecoff/armnt-imports.test
@@ -0,0 +1,11 @@
+# RUN: yaml2obj -format coff -o %t.obj %p/Inputs/armnt-import.obj.yaml
+# RUN: lld -flavor link /out:%t.exe /subsystem:console %t.obj %p/Inputs/library.lib
+# RUN: llvm-readobj -coff-imports %t.exe | FileCheck %s
+
+CHECK: Import {
+CHECK:   Name: library.dll
+CHECK:   ImportLookupTableRVA: 0x4000
+CHECK:   ImportAddressTableRVA: 0x2000
+CHECK:   Symbol: function (0)
+CHECK: }
+