llvm/lib/CodeGen/StackProtector.cpp

		@@ -20,6 +20,7 @@
		#include "llvm/Analysis/BranchProbabilityInfo.h"
		#include "llvm/Analysis/MemoryLocation.h"
		#include "llvm/Analysis/OptimizationRemarkEmitter.h"
		+#include "llvm/CodeGen/Analysis.h"
		#include "llvm/CodeGen/Passes.h"
		#include "llvm/CodeGen/TargetLowering.h"
		#include "llvm/CodeGen/TargetPassConfig.h"
		@@ -625,18 +626,11 @@ bool InsertStackProtectors(const TargetMachine *TM, Function *F,
		HasIRCheck = true;
		// If we're instrumenting a block with a tail call, the check has to be
		- // inserted before the call rather than between it and the return. The
		- // verifier guarantees that a tail call is either directly before the
		- // return or with a single correct bitcast of the return value in between so
		- // we don't need to worry about many situations here.
		+ // inserted before the call rather than between it and the return.
		Instruction *Prev = CheckLoc->getPrevNonDebugInstruction();
		- if (Prev && isa<CallInst>(Prev) && cast<CallInst>(Prev)->isTailCall())
		- CheckLoc = Prev;
		- else if (Prev) {
		- Prev = Prev->getPrevNonDebugInstruction();
		- if (Prev && isa<CallInst>(Prev) && cast<CallInst>(Prev)->isTailCall())
		+ if (auto *CI = dyn_cast_if_present<CallInst>(Prev))
		+ if (CI->isTailCall() && isInTailCallPosition(*CI, *TM))
		CheckLoc = Prev;
		- }
		// Generate epilogue instrumentation. The epilogue intrumentation can be
		// function-based or inlined depending on which mechanism the target is

llvm/test/CodeGen/X86/tailcc-ssp.ll

		@@ -101,3 +101,24 @@ define void @tailcall_unrelated_frame() sspreq {
		tail call void @bar()
		ret void
		}
		+
		+declare void @callee()
		+define void @caller() sspreq {
		+; WINDOWS-LABEL: caller:
		+; WINDOWS: callq callee
		+; WINDOWS: callq callee
		+; WINDOWS: cmpq __security_cookie(%rip), %rcx
		+; WINDOWS: jne
		+; WINDOWS: callq __security_check_cookie
		+
		+; LINUX-LABEL: caller:
		+; LINUX: callq callee@PLT
		+; LINUX: callq callee@PLT
		+; LINUX: cmpq
		+; LINUX: jne
		+; LINUX: callq __stack_chk_fail@PLT
		+
		+ tail call void @callee()
		+ call void @callee()
		+ ret void
		+}