ARM IAS: support .inst directive

This adds support for the .inst directive.  This is an ARM specific directive to
indicate an instruction encoded as a constant expression.  The major difference
between .word, .short, or .byte and .inst is that the latter will be
disassembled as an instruction since it does not get flagged as data.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197657 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 52 insertions, 0 deletions

diff --git a/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp b/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
index deab955640..2d2497895c 100644
--- a/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
+++ b/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
@@ -20,8 +20,10 @@
 #include "ARMUnwindOp.h"
 #include "ARMUnwindOpAsm.h"
 #include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/MC/MCAsmBackend.h"
+#include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCAssembler.h"
 #include "llvm/MC/MCCodeEmitter.h"
 #include "llvm/MC/MCContext.h"
@@ -121,6 +123,7 @@ class ARMTargetAsmStreamer : public ARMTargetStreamer {
   virtual void emitTextAttribute(unsigned Attribute, StringRef String);
   virtual void emitArch(unsigned Arch);
   virtual void emitFPU(unsigned FPU);
+  virtual void emitInst(uint32_t Inst, char Suffix = '\0');
   virtual void finishAttributeSection();
 
 public:
@@ -190,6 +193,13 @@ void ARMTargetAsmStreamer::emitFPU(unsigned FPU) {
 void ARMTargetAsmStreamer::finishAttributeSection() {
 }
 
+void ARMTargetAsmStreamer::emitInst(uint32_t Inst, char Suffix) {
+  OS << "\t.inst";
+  if (Suffix)
+    OS << "." << Suffix;
+  OS << "\t0x" << utohexstr(Inst) << "\n";
+}
+
 class ARMTargetELFStreamer : public ARMTargetStreamer {
 private:
   // This structure holds all attributes, accounting for
@@ -295,6 +305,7 @@ private:
   virtual void emitTextAttribute(unsigned Attribute, StringRef String);
   virtual void emitArch(unsigned Arch);
   virtual void emitFPU(unsigned FPU);
+  virtual void emitInst(uint32_t Inst, char Suffix = '\0');
   virtual void finishAttributeSection();
 
   size_t calculateContentSize() const;
@@ -367,6 +378,44 @@ public:
     MCELFStreamer::EmitInstruction(Inst);
   }
 
+  virtual void emitInst(uint32_t Inst, char Suffix) {
+    unsigned Size;
+    char Buffer[4];
+    const bool LittleEndian = getContext().getAsmInfo()->isLittleEndian();
+
+    switch (Suffix) {
+    case '\0':
+      Size = 4;
+
+      assert(!IsThumb);
+      EmitARMMappingSymbol();
+      for (unsigned II = 0, IE = Size; II != IE; II++) {
+        const unsigned I = LittleEndian ? (Size - II - 1) : II;
+        Buffer[Size - II - 1] = uint8_t(Inst >> I * CHAR_BIT);
+      }
+
+      break;
+    case 'n':
+    case 'w':
+      Size = (Suffix == 'n' ? 2 : 4);
+
+      assert(IsThumb);
+      EmitThumbMappingSymbol();
+      for (unsigned II = 0, IE = Size; II != IE; II = II + 2) {
+        const unsigned I0 = LittleEndian ? II + 0 : (Size - II - 1);
+        const unsigned I1 = LittleEndian ? II + 1 : (Size - II - 2);
+        Buffer[Size - II - 2] = uint8_t(Inst >> I0 * CHAR_BIT);
+        Buffer[Size - II - 1] = uint8_t(Inst >> I1 * CHAR_BIT);
+      }
+
+      break;
+    default:
+      llvm_unreachable("Invalid Suffix");
+    }
+
+    MCELFStreamer::EmitBytes(StringRef(Buffer, Size));
+  }
+
   /// This is one of the functions used to emit data into an ELF section, so the
   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
   /// necessary.
@@ -791,6 +840,9 @@ void ARMTargetELFStreamer::finishAttributeSection() {
   Contents.clear();
   FPU = ARM::INVALID_FPU;
 }
+void ARMTargetELFStreamer::emitInst(uint32_t Inst, char Suffix) {
+  getStreamer().emitInst(Inst, Suffix);
+}
 
 void ARMELFStreamer::FinishImpl() {
   MCTargetStreamer &TS = getTargetStreamer();