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, 15 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/ARMCallingConv.td b/llvm/lib/Target/ARM/ARMCallingConv.td
index 61d2d83ddc4..55111f544ff 100644
--- a/llvm/lib/Target/ARM/ARMCallingConv.td
+++ b/llvm/lib/Target/ARM/ARMCallingConv.td
@@ -246,6 +246,16 @@ def RetCC_ARM_AAPCS_VFP : CallingConv<[
   CCDelegateTo<RetCC_ARM_AAPCS_Common>
 ]>;
 
+
+// Windows Control Flow Guard checks take a single argument (the target function
+// address) and have no return value.
+let Entry = 1 in
+def CC_ARM_Win32_CFGuard_Check : CallingConv<[
+  CCIfType<[i32], CCAssignToReg<[R0]>>
+]>;
+
+
+
 //===----------------------------------------------------------------------===//
 // Callee-saved register lists.
 //===----------------------------------------------------------------------===//
@@ -256,6 +266,11 @@ def CSR_FPRegs : CalleeSavedRegs<(add (sequence "D%u", 0, 31))>;
 def CSR_AAPCS : CalleeSavedRegs<(add LR, R11, R10, R9, R8, R7, R6, R5, R4,
                                      (sequence "D%u", 15, 8))>;
 
+// The Windows Control Flow Guard Check function preserves the same registers as
+// AAPCS, and also preserves all floating point registers.
+def CSR_Win_AAPCS_CFGuard_Check : CalleeSavedRegs<(add LR, R11, R10, R9, R8, R7,
+                                     R6, R5, R4, (sequence "D%u", 15, 0))>;
+
 // R8 is used to pass swifterror, remove it from CSR.
 def CSR_AAPCS_SwiftError : CalleeSavedRegs<(sub CSR_AAPCS, R8)>;