From 5df9f0878be86ccff734eeaf51b20432787d655b Mon Sep 17 00:00:00 2001 From: Hans Wennborg Date: Tue, 5 Dec 2017 20:22:20 +0000 Subject: Re-commit r319490 "XOR the frame pointer with the stack cookie when protecting the stack" The patch originally broke Chromium (crbug.com/791714) due to its failing to specify that the new pseudo instructions clobber EFLAGS. This commit fixes that. > Summary: This strengthens the guard and matches MSVC. > > Reviewers: hans, etienneb > > Subscribers: hiraditya, JDevlieghere, vlad.tsyrklevich, llvm-commits > > Differential Revision: https://reviews.llvm.org/D40622 llvm-svn: 319824 --- llvm/lib/CodeGen/StackProtector.cpp | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'llvm/lib/CodeGen/StackProtector.cpp') diff --git a/llvm/lib/CodeGen/StackProtector.cpp b/llvm/lib/CodeGen/StackProtector.cpp index e3340028863..62cef95a4af 100644 --- a/llvm/lib/CodeGen/StackProtector.cpp +++ b/llvm/lib/CodeGen/StackProtector.cpp @@ -385,8 +385,12 @@ static bool CreatePrologue(Function *F, Module *M, ReturnInst *RI, /// - The epilogue checks the value stored in the prologue against the original /// value. It calls __stack_chk_fail if they differ. bool StackProtector::InsertStackProtectors() { + // If the target wants to XOR the frame pointer into the guard value, it's + // impossible to emit the check in IR, so the target *must* support stack + // protection in SDAG. bool SupportsSelectionDAGSP = - EnableSelectionDAGSP && !TM->Options.EnableFastISel; + TLI->useStackGuardXorFP() || + (EnableSelectionDAGSP && !TM->Options.EnableFastISel); AllocaInst *AI = nullptr; // Place on stack that stores the stack guard. for (Function::iterator I = F->begin(), E = F->end(); I != E;) { -- cgit v1.2.3