Add to the disassembler C API an option to print the disassembled

instructions in the assembly code variant if one exists.

The intended use for this is so tools like lldb and darwin's otool(1)
can be switched to print Intel-flavored disassembly.

I discussed extensively this API with Jim Grosbach and we feel
while it may not be fully general, in reality there is only one syntax
for each assembly with the exception of X86 which has exactly
two for historical reasons.

rdar://10989182


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170477 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 22 insertions, 0 deletions

diff --git a/include/llvm-c/Disassembler.h b/include/llvm-c/Disassembler.h
index f0872c1436..df65a7b208 100644
--- a/include/llvm-c/Disassembler.h
+++ b/include/llvm-c/Disassembler.h
@@ -168,6 +168,8 @@ int LLVMSetDisasmOptions(LLVMDisasmContextRef DC, uint64_t Options);
 #define LLVMDisassembler_Option_UseMarkup 1
 /* The option to print immediates as hex. */
 #define LLVMDisassembler_Option_PrintImmHex 2
+/* The option use the other assembler printer variant */
+#define LLVMDisassembler_Option_AsmPrinterVariant 4
 
 /**
  * Dispose of a disassembler context.
diff --git a/lib/MC/MCDisassembler/Disassembler.cpp b/lib/MC/MCDisassembler/Disassembler.cpp
index ac583ac127..d3fa906a06 100644
--- a/lib/MC/MCDisassembler/Disassembler.cpp
+++ b/lib/MC/MCDisassembler/Disassembler.cpp
@@ -195,5 +195,21 @@ int LLVMSetDisasmOptions(LLVMDisasmContextRef DCR, uint64_t Options){
       IP->setPrintImmHex(1);
       Options &= ~LLVMDisassembler_Option_PrintImmHex;
   }
+  if (Options & LLVMDisassembler_Option_AsmPrinterVariant){
+      LLVMDisasmContext *DC = (LLVMDisasmContext *)DCR;
+      // Try to set up the new instruction printer.
+      const MCAsmInfo *MAI = DC->getAsmInfo();
+      const MCInstrInfo *MII = DC->getInstrInfo();
+      const MCRegisterInfo *MRI = DC->getRegisterInfo();
+      const MCSubtargetInfo *STI = DC->getSubtargetInfo();
+      int AsmPrinterVariant = MAI->getAssemblerDialect();
+      AsmPrinterVariant = AsmPrinterVariant == 0 ? 1 : 0;
+      MCInstPrinter *IP = DC->getTarget()->createMCInstPrinter(
+          AsmPrinterVariant, *MAI, *MII, *MRI, *STI);
+      if (IP) {
+        DC->setIP(IP);
+        Options &= ~LLVMDisassembler_Option_AsmPrinterVariant;
+      }
+  }
   return (Options == 0);
 }
diff --git a/lib/MC/MCDisassembler/Disassembler.h b/lib/MC/MCDisassembler/Disassembler.h
index 28cf04b95d..6eb59d0c57 100644
--- a/lib/MC/MCDisassembler/Disassembler.h
+++ b/lib/MC/MCDisassembler/Disassembler.h
@@ -109,7 +109,11 @@ public:
   const Target *getTarget() const { return TheTarget; }
   const MCDisassembler *getDisAsm() const { return DisAsm.get(); }
   const MCAsmInfo *getAsmInfo() const { return MAI.get(); }
+  const MCInstrInfo *getInstrInfo() const { return MII.get(); }
+  const MCRegisterInfo *getRegisterInfo() const { return MRI.get(); }
+  const MCSubtargetInfo *getSubtargetInfo() const { return MSI.get(); }
   MCInstPrinter *getIP() { return IP.get(); }
+  void setIP(MCInstPrinter *NewIP) { IP.reset(NewIP); }
 };
 
 } // namespace llvm