Teach LLVM about the PPC64 memory sanitizer implementation.

[foad]

Summary

This is the LLVM part of the PPC memory sanitizer implementation in
D10648.

[eugenis]

LGTM

lib/Transforms/Instrumentation/MemorySanitizer.cpp

 // mips64 Linux
 static const MemoryMapParams Linux_MIPS64_MemoryMapParams = {
   0x004000000000,  // AndMask
   0,               // XorMask (not used)
   0,               // ShadowBase (not used)
   0x002000000000,  // OriginBase
 };
 
+// ppc64 Linux
+static const MemoryMapParams Linux_PowerPC64_MemoryMapParams = {
+  0x200000000000,  // AndMask
+  0x100000000000,  // XorMask
+  0x080000000000,  // ShadowBase
+  0x1C0000000000,  // OriginBase
+};
+
 // i386 FreeBSD
 static const MemoryMapParams FreeBSD_I386_MemoryMapParams = {
   0x000180000000,  // AndMask
   0x000040000000,  // XorMask
   0x000020000000,  // ShadowBase
   0x000700000000,  // OriginBase
 };
 
static const PlatformMemoryMapParams Linux_X86_MemoryMapParams = {
   &Linux_X86_64_MemoryMapParams,
 };
 
 static const PlatformMemoryMapParams Linux_MIPS_MemoryMapParams = {
   NULL,
   &Linux_MIPS64_MemoryMapParams,
 };
 
+static const PlatformMemoryMapParams Linux_PowerPC_MemoryMapParams = {
+  NULL,
+  &Linux_PowerPC64_MemoryMapParams,
+};
+
 static const PlatformMemoryMapParams FreeBSD_X86_MemoryMapParams = {
   &FreeBSD_I386_MemoryMapParams,
   &FreeBSD_X86_64_MemoryMapParams,
 };
 
 /// \brief An instrumentation pass implementing detection of uninitialized
 /// reads.
 ///
case Triple::Linux:
           break;
         case Triple::x86:
           MapParams = Linux_X86_MemoryMapParams.bits32;
           break;
         case Triple::mips64:
         case Triple::mips64el:
           MapParams = Linux_MIPS_MemoryMapParams.bits64;
           break;
+        case Triple::ppc64:
+        case Triple::ppc64le:
+          MapParams = Linux_PowerPC_MemoryMapParams.bits64;
+          break;
         default:
           report_fatal_error("unsupported architecture");
       }
       break;
     default:
       report_fatal_error("unsupported operating system");
   }