[HWASan] Enable globals support for LAM.

compiler-rt/test/hwasan/TestCases/global.c

 // RUN: %clang_hwasan %s -o %t
 // RUN: %run %t 0
 // RUN: not %run %t 1 2>&1 | FileCheck --check-prefixes=CHECK,RSYM %s
 // RUN: not %env_hwasan_opts=symbolize=0 %run %t 1 2>&1 | FileCheck --check-prefixes=CHECK,RNOSYM %s
 // RUN: not %run %t -1 2>&1 | FileCheck --check-prefixes=CHECK,LSYM %s
 // RUN: not %env_hwasan_opts=symbolize=0 %run %t -1 2>&1 | FileCheck --check-prefixes=CHECK,LNOSYM %s
 
-// Global aliasing is not implemented on x86.
-// XFAIL: x86_64
+// REQUIRES: pointer-tagging
 
 int x = 1;
 
 int main(int argc, char **argv) {
   // RSYM: is located 0 bytes to the right of 4-byte global variable x {{.*}} in {{.*}}global.c.tmp
   // RNOSYM: is located to the right of a 4-byte global variable in ({{.*}}global.c.tmp+{{.*}})
   // LSYM: is located 4 bytes to the left of 4-byte global variable x {{.*}} in {{.*}}global.c.tmp
   // LNOSYM: is located to the left of a 4-byte global variable in ({{.*}}global.c.tmp+{{.*}})
   // CHECK-NOT: can not describe
   (&x)[atoi(argv[1])] = 1;
 }

llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp

 void HWAddressSanitizer::initializeModule() {
   LLVM_DEBUG(dbgs() << "Init " << M.getName() << "\n");
   auto &DL = M.getDataLayout();
 
   TargetTriple = Triple(M.getTargetTriple());
 
   // x86_64 currently has two modes:
   // - Intel LAM (default)
-  // - pointer aliasing
-  // Pointer aliasing mode is heap only.  LAM mode is heap+stack, with support
-  // planned for globals as well.
+  // - pointer aliasing (heap only)
   bool IsX86_64 = TargetTriple.getArch() == Triple::x86_64;
   UsePageAliases = ClUsePageAliases && IsX86_64;
   InstrumentWithCalls = IsX86_64 ? true : ClInstrumentWithCalls;
   InstrumentStack = UsePageAliases ? false : ClInstrumentStack;
   PointerTagShift = IsX86_64 ? 57 : 56;
   TagMaskByte = IsX86_64 ? 0x3F : 0xFF;
 
   Mapping.init(TargetTriple, InstrumentWithCalls);
InstrumentLandingPads = ClInstrumentLandingPads.getNumOccurrences()
                               ? ClInstrumentLandingPads
                               : !NewRuntime;
 
   if (!CompileKernel) {
     createHwasanCtorComdat();
     bool InstrumentGlobals =
         ClGlobals.getNumOccurrences() ? ClGlobals : NewRuntime;
 
-    // TODO: Support globals for x86_64 in non-aliasing mode.
-    if (InstrumentGlobals && !IsX86_64)
+    if (InstrumentGlobals && !UsePageAliases)
       instrumentGlobals();
 
     bool InstrumentPersonalityFunctions =
         ClInstrumentPersonalityFunctions.getNumOccurrences()
             ? ClInstrumentPersonalityFunctions
             : NewRuntime;
     if (InstrumentPersonalityFunctions)
       instrumentPersonalityFunctions();
for (GlobalVariable &GV : M.globals()) {
 
     Globals.push_back(&GV);
   }
 
   MD5 Hasher;
   Hasher.update(M.getSourceFileName());
   MD5::MD5Result Hash;
   Hasher.final(Hash);
-  uint8_t Tag = Hash[0];
+  uint8_t Tag = Hash[0] & TagMaskByte;
 
   for (GlobalVariable *GV : Globals) {
     // Skip tag 0 in order to avoid collisions with untagged memory.
     if (Tag == 0)
       Tag = 1;
     instrumentGlobal(GV, Tag++);
   }
 }

llvm/test/Instrumentation/HWAddressSanitizer/X86/globals.ll

+; RUN: opt < %s -S -hwasan -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+; CHECK: @__start_hwasan_globals = external hidden constant [0 x i8]
+; CHECK: @__stop_hwasan_globals = external hidden constant [0 x i8]
+
+; CHECK: @hwasan.note = private constant { i32, i32, i32, [8 x i8], i32, i32 } { i32 8, i32 8, i32 3, [8 x i8] c"LLVM\00\00\00\00", i32 trunc (i64 sub (i64 ptrtoint ([0 x i8]* @__start_hwasan_globals to i64), i64 ptrtoint ({ i32, i32, i32, [8 x i8], i32, i32 }* @hwasan.note to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([0 x i8]* @__stop_hwasan_globals to i64), i64 ptrtoint ({ i32, i32, i32, [8 x i8], i32, i32 }* @hwasan.note to i64)) to i32) }, section ".note.hwasan.globals", comdat($hwasan.module_ctor), align 4
+
+; CHECK: @hwasan.dummy.global = private constant [0 x i8] zeroinitializer, section "hwasan_globals", comdat($hwasan.module_ctor), !associated [[NOTE:![0-9]+]]
+
+; CHECK: @four.hwasan = private global { i32, [12 x i8] } { i32 1, [12 x i8] c"\00\00\00\00\00\00\00\00\00\00\00," }, align 16
+; CHECK: @four.hwasan.descriptor = private constant { i32, i32 } { i32 trunc (i64 sub (i64 ptrtoint ({ i32, [12 x i8] }* @four.hwasan to i64), i64 ptrtoint ({ i32, i32 }* @four.hwasan.descriptor to i64)) to i32), i32 738197508 }, section "hwasan_globals", !associated [[FOUR:![0-9]+]]
+
+; CHECK: @sixteen.hwasan = private global [16 x i8] zeroinitializer, align 16
+; CHECK: @sixteen.hwasan.descriptor = private constant { i32, i32 } { i32 trunc (i64 sub (i64 ptrtoint ([16 x i8]* @sixteen.hwasan to i64), i64 ptrtoint ({ i32, i32 }* @sixteen.hwasan.descriptor to i64)) to i32), i32 754974736 }, section "hwasan_globals", !associated [[SIXTEEN:![0-9]+]]
+
+; CHECK: @huge.hwasan = private global [16777232 x i8] zeroinitializer, align 16
+; CHECK: @huge.hwasan.descriptor = private constant { i32, i32 } { i32 trunc (i64 sub (i64 ptrtoint ([16777232 x i8]* @huge.hwasan to i64), i64 ptrtoint ({ i32, i32 }* @huge.hwasan.descriptor to i64)) to i32), i32 788529136 }, section "hwasan_globals", !associated [[HUGE:![0-9]+]]
+; CHECK: @huge.hwasan.descriptor.1 = private constant { i32, i32 } { i32 trunc (i64 add (i64 sub (i64 ptrtoint ([16777232 x i8]* @huge.hwasan to i64), i64 ptrtoint ({ i32, i32 }* @huge.hwasan.descriptor.1 to i64)), i64 16777200) to i32), i32 771751968 }, section "hwasan_globals", !associated [[HUGE]]
+
+; CHECK: @four = alias i32, inttoptr (i64 add (i64 ptrtoint ({ i32, [12 x i8] }* @four.hwasan to i64), i64 6341068275337658368) to i32*)
+; CHECK: @sixteen = alias [16 x i8], inttoptr (i64 add (i64 ptrtoint ([16 x i8]* @sixteen.hwasan to i64), i64 6485183463413514240) to [16 x i8]*)
+; CHECK: @huge = alias [16777232 x i8], inttoptr (i64 add (i64 ptrtoint ([16777232 x i8]* @huge.hwasan to i64), i64 6629298651489370112) to [16777232 x i8]*)
+
+; CHECK: [[NOTE]] = !{{{{}} i32, i32, i32, [8 x i8], i32, i32 }* @hwasan.note}
+; CHECK: [[FOUR]] = !{{{{}} i32, [12 x i8] }* @four.hwasan}
+; CHECK: [[SIXTEEN]] = !{[16 x i8]* @sixteen.hwasan}
+; CHECK: [[HUGE]] = !{[16777232 x i8]* @huge.hwasan}
+
+source_filename = "foo"
+
+@four = global i32 1
+@sixteen = global [16 x i8] zeroinitializer
+@huge = global [16777232 x i8] zeroinitializer