2 files changed, 12 insertions, 7 deletions
diff --git a/llvm/lib/Target/X86/X86SpeculativeLoadHardening.cpp b/llvm/lib/Target/X86/X86SpeculativeLoadHardening.cpp
index e9b4032a199..7979315a2ae 100644
--- a/llvm/lib/Target/X86/X86SpeculativeLoadHardening.cpp
+++ b/llvm/lib/Target/X86/X86SpeculativeLoadHardening.cpp
@@ -75,6 +75,11 @@ STATISTIC(NumCallsOrJumpsHardened,
 STATISTIC(NumInstsInserted, "Number of instructions inserted");
 STATISTIC(NumLFENCEsInserted, "Number of lfence instructions inserted");
 
+static cl::opt<bool> EnableSpeculativeLoadHardening(
+    "x86-speculative-load-hardening",
+    cl::desc("Force enable speculative load hardening"), cl::init(false),
+    cl::Hidden);
+
 static cl::opt<bool> HardenEdgesWithLFENCE(
     PASS_KEY "-lfence",
     cl::desc(
@@ -404,6 +409,12 @@ bool X86SpeculativeLoadHardeningPass::runOnMachineFunction(
   LLVM_DEBUG(dbgs() << "********** " << getPassName() << " : " << MF.getName()
                     << " **********\n");
 
+  // Only run if this pass is forced enabled or we detect the relevant function
+  // attribute requesting SLH.
+  if (!EnableSpeculativeLoadHardening &&
+      !MF.getFunction().hasFnAttribute(Attribute::SpeculativeLoadHardening))
+    return false;
+
   Subtarget = &MF.getSubtarget<X86Subtarget>();
   MRI = &MF.getRegInfo();
   TII = Subtarget->getInstrInfo();
diff --git a/llvm/lib/Target/X86/X86TargetMachine.cpp b/llvm/lib/Target/X86/X86TargetMachine.cpp
index 969cd0ab7e7..dd1bbc761b2 100644
--- a/llvm/lib/Target/X86/X86TargetMachine.cpp
+++ b/llvm/lib/Target/X86/X86TargetMachine.cpp
@@ -54,10 +54,6 @@ static cl::opt<bool> EnableMachineCombinerPass("x86-machine-combiner",
                                cl::desc("Enable the machine combiner pass"),
                                cl::init(true), cl::Hidden);
 
-static cl::opt<bool> EnableSpeculativeLoadHardening(
-    "x86-speculative-load-hardening",
-    cl::desc("Enable speculative load hardening"), cl::init(false), cl::Hidden);
-
 namespace llvm {
 
 void initializeWinEHStatePassPass(PassRegistry &);
@@ -475,9 +471,7 @@ void X86PassConfig::addPreRegAlloc() {
     addPass(createX86AvoidStoreForwardingBlocks());
   }
 
-  if (EnableSpeculativeLoadHardening)
-    addPass(createX86SpeculativeLoadHardeningPass());
-
+  addPass(createX86SpeculativeLoadHardeningPass());
   addPass(createX86FlagsCopyLoweringPass());
   addPass(createX86WinAllocaExpander());
 }