[PowerPC][asan] Update asan to handle changed memory layouts in newer kernels

[seurer]

Summary

[PowerPC][asan] Update asan to handle changed memory layouts in newer kernels

In more recent Linux kernels with 47 bit VMAs the layout of virtual memory
for powerpc64 changed causing the address sanitizer to not work properly. This
patch adds support for 47 bit VMA kernels for powerpc64 and fixes up test
cases.

There is an associated patch for compiler-rt.

Tested on several 4.x and 3.x kernel releases.

[seurer]

compiler-rt part: https://reviews.llvm.org/D40908

lib/Transforms/Instrumentation/AddressSanitizer.cpp

 static const uint64_t kDynamicShadowSentinel =
     std::numeric_limits<uint64_t>::max();
 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
 static const uint64_t kIOSSimShadowOffset32 = 1ULL << 30;
 static const uint64_t kIOSSimShadowOffset64 = kDefaultShadowOffset64;
 static const uint64_t kSmallX86_64ShadowOffsetBase = 0x7FFFFFFF;  // < 2G.
 static const uint64_t kSmallX86_64ShadowOffsetAlignMask = ~0xFFFULL;
 static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
-static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
+static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 44;
 static const uint64_t kSystemZ_ShadowOffset64 = 1ULL << 52;
 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
 static const uint64_t kNetBSD_ShadowOffset64 = 1ULL << 46;
 static const uint64_t kPS4CPU_ShadowOffset64 = 1ULL << 40;

test/Instrumentation/AddressSanitizer/stack-poisoning-and-lifetime-be.ll

entry:
   %xx = getelementptr inbounds [650 x i8], [650 x i8]* %x, i64 0, i64 0
 
   %y = alloca [13 x i8], align 1
   %yy = getelementptr inbounds [13 x i8], [13 x i8]* %y, i64 0, i64 0
 
   %z = alloca [40 x i8], align 1
   %zz = getelementptr inbounds [40 x i8], [40 x i8]* %z, i64 0, i64 0
 
-  ; CHECK: [[SHADOW_BASE:%[0-9]+]] = add i64 %{{[0-9]+}}, 2199023255552
+  ; CHECK: [[SHADOW_BASE:%[0-9]+]] = add i64 %{{[0-9]+}}, 17592186044416
 
   ; F1F1F1F1
   ; ENTRY-NEXT: [[OFFSET:%[0-9]+]] = add i64 [[SHADOW_BASE]], 0
   ; ENTRY-NEXT: [[PTR:%[0-9]+]] = inttoptr i64 [[OFFSET]] to [[TYPE:i32]]*
   ; ENTRY-NEXT: store [[TYPE]] -235802127, [[TYPE]]* [[PTR]], align 1
 
   ; 02F2F2F2F2F2F2F2
   ; ENTRY-NEXT: [[OFFSET:%[0-9]+]] = add i64 [[SHADOW_BASE]], 85