Add Windows Control Flow Guard checks (/guard:cf).

Summary:
A new function pass (Transforms/CFGuard/CFGuard.cpp) inserts CFGuard checks on
indirect function calls, using either the check mechanism (X86, ARM, AArch64) or
or the dispatch mechanism (X86-64). The check mechanism requires a new calling
convention for the supported targets. The dispatch mechanism adds the target as
an operand bundle, which is processed by SelectionDAG. Another pass
(CodeGen/CFGuardLongjmp.cpp) identifies and emits valid longjmp targets, as
required by /guard:cf. This feature is enabled using the `cfguard` CC1 option.

Reviewers: thakis, rnk, theraven, pcc

Subscribers: ychen, hans, metalcanine, dmajor, tomrittervg, alex, mehdi_amini, mgorny, javed.absar, kristof.beyls, hiraditya, steven_wu, dexonsmith, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D65761

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index bb6bca51efd..6e511e68d7a 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -1855,6 +1855,7 @@ ARMTargetLowering::getEffectiveCallingConv(CallingConv::ID CC,
   case CallingConv::ARM_AAPCS:
   case CallingConv::ARM_APCS:
   case CallingConv::GHC:
+  case CallingConv::CFGuard_Check:
     return CC;
   case CallingConv::PreserveMost:
     return CallingConv::PreserveMost;
@@ -1914,6 +1915,8 @@ CCAssignFn *ARMTargetLowering::CCAssignFnForNode(CallingConv::ID CC,
     return (Return ? RetCC_ARM_APCS : CC_ARM_APCS_GHC);
   case CallingConv::PreserveMost:
     return (Return ? RetCC_ARM_AAPCS : CC_ARM_AAPCS);
+  case CallingConv::CFGuard_Check:
+    return (Return ? RetCC_ARM_AAPCS : CC_ARM_Win32_CFGuard_Check);
   }
 }