From 14945186c28ee41162eedc7fa89e04548f2bda6d Mon Sep 17 00:00:00 2001
From: Paul Robinson <paul.robinson@sony.com>
Date: Mon, 30 Sep 2019 15:01:35 +0000
Subject: [SSP] [1/3] Revert "StackProtector: Use PointerMayBeCaptured"
 "Captured" and "relevant to Stack Protector" are not the same thing.

This reverts commit f29366b1f594f48465c5a2754bcffac6d70fd0b1.
aka r363169.

Differential Revision: https://reviews.llvm.org/D67842

llvm-svn: 373216
---
 llvm/lib/CodeGen/StackProtector.cpp | 39 +++++++++++++++++++++++++++++++++----
 1 file changed, 35 insertions(+), 4 deletions(-)

(limited to 'llvm/lib/CodeGen/StackProtector.cpp')

diff --git a/llvm/lib/CodeGen/StackProtector.cpp b/llvm/lib/CodeGen/StackProtector.cpp
index 809960c7fdf..dc215a033fc 100644
--- a/llvm/lib/CodeGen/StackProtector.cpp
+++ b/llvm/lib/CodeGen/StackProtector.cpp
@@ -17,7 +17,6 @@
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/BranchProbabilityInfo.h"
-#include "llvm/Analysis/CaptureTracking.h"
 #include "llvm/Analysis/EHPersonalities.h"
 #include "llvm/Analysis/OptimizationRemarkEmitter.h"
 #include "llvm/CodeGen/Passes.h"
@@ -157,6 +156,40 @@ bool StackProtector::ContainsProtectableArray(Type *Ty, bool &IsLarge,
   return NeedsProtector;
 }
 
+bool StackProtector::HasAddressTaken(const Instruction *AI) {
+  for (const User *U : AI->users()) {
+    if (const StoreInst *SI = dyn_cast<StoreInst>(U)) {
+      if (AI == SI->getValueOperand())
+        return true;
+    } else if (const PtrToIntInst *SI = dyn_cast<PtrToIntInst>(U)) {
+      if (AI == SI->getOperand(0))
+        return true;
+    } else if (const CallInst *CI = dyn_cast<CallInst>(U)) {
+      // Ignore intrinsics that are not calls. TODO: Use isLoweredToCall().
+      if (!isa<DbgInfoIntrinsic>(CI) && !CI->isLifetimeStartOrEnd())
+        return true;
+    } else if (isa<InvokeInst>(U)) {
+      return true;
+    } else if (const SelectInst *SI = dyn_cast<SelectInst>(U)) {
+      if (HasAddressTaken(SI))
+        return true;
+    } else if (const PHINode *PN = dyn_cast<PHINode>(U)) {
+      // Keep track of what PHI nodes we have already visited to ensure
+      // they are only visited once.
+      if (VisitedPHIs.insert(PN).second)
+        if (HasAddressTaken(PN))
+          return true;
+    } else if (const GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) {
+      if (HasAddressTaken(GEP))
+        return true;
+    } else if (const BitCastInst *BI = dyn_cast<BitCastInst>(U)) {
+      if (HasAddressTaken(BI))
+        return true;
+    }
+  }
+  return false;
+}
+
 /// Search for the first call to the llvm.stackprotector intrinsic and return it
 /// if present.
 static const CallInst *findStackProtectorIntrinsic(Function &F) {
@@ -264,9 +297,7 @@ bool StackProtector::RequiresStackProtector() {
           continue;
         }
 
-        if (Strong && PointerMayBeCaptured(AI,
-                                           /* ReturnCaptures */ false,
-                                           /* StoreCaptures */ true)) {
+        if (Strong && HasAddressTaken(AI)) {
           ++NumAddrTaken;
           Layout.insert(std::make_pair(AI, MachineFrameInfo::SSPLK_AddrOf));
           ORE.emit([&]() {
-- 
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