[llvm] CodeGen: Remove overrides of getSSPStackGuardCheck (PR #164044)

[Martin Storsjö via llvm-commits]

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@@ -640,15 +640,6 @@ void X86TargetLowering::insertSSPDeclarations(Module &M) const {
   TargetLowering::insertSSPDeclarations(M);
 }
 
-Function *X86TargetLowering::getSSPStackGuardCheck(const Module &M) const {
-  // MSVC CRT has a function to validate security cookie.
-  if (Subtarget.getTargetTriple().isWindowsMSVCEnvironment() ||
-      Subtarget.getTargetTriple().isWindowsItaniumEnvironment()) {
-    return M.getFunction("__security_check_cookie");
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mstorsjo wrote:

The arm/aarch64 and now generalized code doesn't have these checks for the actual target - and I don't see any such conditionals around any definition of `RTLIB::SECURITY_CHECK_COOKIE` either (I only see that defined in `include/llvm/IR/RuntimeLibcalls.td` I think?), so it doesn't look obviously equivalent, even though I presume it practically is.

https://github.com/llvm/llvm-project/pull/164044