RuntimeLibcalls: Add entries for stackprotector globals (#154930)

Add entries for_stack_chk_guard, __ssp_canary_word, __security_cookie,
and __guard_local. As far as I can tell these are all just different
names for the same shaped functionality on different systems.

These aren't really functions, but special global variable names. They
should probably be treated the same way; all the same contexts that
need to know about emittable function names also need to know about
this. This avoids a special case check in IRSymtab.

This isn't a complete change, there's a lot more cleanup which
should be done. The stack protector configuration system is a
complete mess. There are multiple overlapping controls, used in
3 different places. Some of the target control implementations overlap
with conditions used in the emission points, and some use correlated
but not identical conditions in different contexts.

i.e. useLoadStackGuardNode, getIRStackGuard, getSSPStackGuardCheck and
insertSSPDeclarations are all used in inconsistent ways so I don't know
if I've tracked the intention of the system correctly.

The PowerPC test change is a bug fix on linux. Previously the manual
conditions were based around !isOSOpenBSD, which is not the condition
where __stack_chk_guard are used. Now getSDagStackGuard returns the
proper global reference, resulting in LOAD_STACK_GUARD getting a
MachineMemOperand which allows scheduling.

1 files changed, 26 insertions, 18 deletions

diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
index 350948a..9ffced8 100644
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -2059,29 +2059,37 @@ Value *TargetLoweringBase::getIRStackGuard(IRBuilderBase &IRB) const {
 // Currently only support "standard" __stack_chk_guard.
 // TODO: add LOAD_STACK_GUARD support.
 void TargetLoweringBase::insertSSPDeclarations(Module &M) const {
-  if (!M.getNamedValue("__stack_chk_guard")) {
-    auto *GV = new GlobalVariable(M, PointerType::getUnqual(M.getContext()),
-                                  false, GlobalVariable::ExternalLinkage,
-                                  nullptr, "__stack_chk_guard");
-
-    // FreeBSD has "__stack_chk_guard" defined externally on libc.so
-    if (M.getDirectAccessExternalData() &&
-        !TM.getTargetTriple().isOSCygMing() &&
-        !(TM.getTargetTriple().isPPC64() &&
-          TM.getTargetTriple().isOSFreeBSD()) &&
-        (!TM.getTargetTriple().isOSDarwin() ||
-         TM.getRelocationModel() == Reloc::Static))
-      GV->setDSOLocal(true);
-  }
+  RTLIB::LibcallImpl StackGuardImpl = getLibcallImpl(RTLIB::STACK_CHECK_GUARD);
+  if (StackGuardImpl == RTLIB::Unsupported)
+    return;
+
+  StringRef StackGuardVarName = getLibcallImplName(StackGuardImpl);
+  M.getOrInsertGlobal(
+      StackGuardVarName, PointerType::getUnqual(M.getContext()), [=, &M]() {
+        auto *GV = new GlobalVariable(M, PointerType::getUnqual(M.getContext()),
+                                      false, GlobalVariable::ExternalLinkage,
+                                      nullptr, StackGuardVarName);
+
+        // FreeBSD has "__stack_chk_guard" defined externally on libc.so
+        if (M.getDirectAccessExternalData() &&
+            !TM.getTargetTriple().isOSCygMing() &&
+            !(TM.getTargetTriple().isPPC64() &&
+              TM.getTargetTriple().isOSFreeBSD()) &&
+            (!TM.getTargetTriple().isOSDarwin() ||
+             TM.getRelocationModel() == Reloc::Static))
+          GV->setDSOLocal(true);
+
+        return GV;
+      });
 }
 
 // Currently only support "standard" __stack_chk_guard.
 // TODO: add LOAD_STACK_GUARD support.
 Value *TargetLoweringBase::getSDagStackGuard(const Module &M) const {
-  if (getTargetMachine().getTargetTriple().isOSOpenBSD()) {
-    return M.getNamedValue("__guard_local");
-  }
-  return M.getNamedValue("__stack_chk_guard");
+  RTLIB::LibcallImpl GuardVarImpl = getLibcallImpl(RTLIB::STACK_CHECK_GUARD);
+  if (GuardVarImpl == RTLIB::Unsupported)
+    return nullptr;
+  return M.getNamedValue(getLibcallImplName(GuardVarImpl));
 }
 
 Function *TargetLoweringBase::getSSPStackGuardCheck(const Module &M) const {