[Driver] Make -fsanitize=kcfi,function incompatible

[MaskRay]

Summary

A -fsanitize=kcfi instrumented function has a special instruction/data
before the function entry at a fixed offset.
A -fsanitize=function instrumented function has special instruction/data
after the function entry at a fixed offset (may change to *before* in D148665).

The two instrumentations are not intended to be used together and will become
incompatible after D148665.

[MaskRay]

rebase

clang/lib/Driver/SanitizerArgs.cpp

static const SanitizerMask NeedsUbsanRt =
     SanitizerKind::CFI | SanitizerKind::FloatDivideByZero |
     SanitizerKind::ObjCCast;
 static const SanitizerMask NeedsUbsanCxxRt =
     SanitizerKind::Vptr | SanitizerKind::CFI;
 static const SanitizerMask NotAllowedWithTrap = SanitizerKind::Vptr;
 static const SanitizerMask NotAllowedWithMinimalRuntime =
     SanitizerKind::Function | SanitizerKind::Vptr;
 static const SanitizerMask RequiresPIE =
-    SanitizerKind::DataFlow | SanitizerKind::Scudo | SanitizerKind::KCFI;
+    SanitizerKind::DataFlow | SanitizerKind::Scudo;
 static const SanitizerMask NeedsUnwindTables =
     SanitizerKind::Address | SanitizerKind::HWAddress | SanitizerKind::Thread |
     SanitizerKind::Memory | SanitizerKind::DataFlow;
 static const SanitizerMask SupportsCoverage =
     SanitizerKind::Address | SanitizerKind::HWAddress |
     SanitizerKind::KernelAddress | SanitizerKind::KernelHWAddress |
     SanitizerKind::MemtagStack | SanitizerKind::MemtagHeap |
     SanitizerKind::MemtagGlobals | SanitizerKind::Memory |
std::pair<SanitizerMask, SanitizerMask> IncompatibleGroups[] = {
       std::make_pair(SanitizerKind::KernelMemory,
                      SanitizerKind::Address | SanitizerKind::HWAddress |
                          SanitizerKind::Leak | SanitizerKind::Thread |
                          SanitizerKind::Memory | SanitizerKind::KernelAddress |
                          SanitizerKind::Scudo | SanitizerKind::SafeStack),
       std::make_pair(SanitizerKind::MemTag,
                      SanitizerKind::Address | SanitizerKind::KernelAddress |
                          SanitizerKind::HWAddress |
-                         SanitizerKind::KernelHWAddress)};
+                         SanitizerKind::KernelHWAddress),
+      std::make_pair(SanitizerKind::KCFI, SanitizerKind::Function)};
   // Enable toolchain specific default sanitizers if not explicitly disabled.
   SanitizerMask Default = TC.getDefaultSanitizers() & ~AllRemove;
 
   // Disable default sanitizers that are incompatible with explicitly requested
   // ones.
   for (auto G : IncompatibleGroups) {
     SanitizerMask Group = G.first;
     if ((Default & Group) && (Kinds & G.second))

clang/test/Driver/fsanitize.c

 // CHECK-KCFI-NOTRAP: error: unsupported argument 'kcfi' to option '-fsanitize-trap='
 
 // RUN: %clang --target=x86_64-linux-gnu -fsanitize=kcfi %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-KCFI
 // CHECK-KCFI: "-fsanitize=kcfi"
 
 // RUN: %clang --target=x86_64-linux-gnu -fsanitize=kcfi -fno-sanitize-recover=kcfi %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-KCFI-RECOVER
 // CHECK-KCFI-RECOVER: error: unsupported argument 'kcfi' to option '-fno-sanitize-recover='
 
+// RUN: %clang --target=x86_64-linux-gnu -fsanitize=kcfi,function %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-KCFI-FUNCTION
+// CHECK-KCFI-FUNCTION: error: invalid argument '-fsanitize=kcfi' not allowed with '-fsanitize=function'
+
 // RUN: %clang_cl -fsanitize=address -c -MDd -### -- %s 2>&1 | FileCheck %s -check-prefix=CHECK-ASAN-DEBUGRTL
 // RUN: %clang_cl -fsanitize=address -c -MTd -### -- %s 2>&1 | FileCheck %s -check-prefix=CHECK-ASAN-DEBUGRTL
 // RUN: %clang_cl -fsanitize=address -c -LDd -### -- %s 2>&1 | FileCheck %s -check-prefix=CHECK-ASAN-DEBUGRTL
 // RUN: %clang_cl -fsanitize=address -c -MD -MDd -### -- %s 2>&1 | FileCheck %s -check-prefix=CHECK-ASAN-DEBUGRTL
 // RUN: %clang_cl -fsanitize=address -c -MT -MTd -### -- %s 2>&1 | FileCheck %s -check-prefix=CHECK-ASAN-DEBUGRTL
 // RUN: %clang_cl -fsanitize=address -c -LD -LDd -### -- %s 2>&1 | FileCheck %s -check-prefix=CHECK-ASAN-DEBUGRTL
 // CHECK-ASAN-DEBUGRTL: error: invalid argument
 // CHECK-ASAN-DEBUGRTL: not allowed with '-fsanitize=address'