[llvm] Provide intrinsics for speculative loads (PR #179642)

[Nikita Popov via llvm-commits]

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@@ -6854,6 +6854,70 @@ void Verifier::visitIntrinsicCall(Intrinsic::ID ID, CallBase &Call) {
           &Call);
     break;
   }
+  case Intrinsic::speculative_load: {
+    Type *LoadTy = Call.getType();
+    TypeSize Size = DL.getTypeStoreSize(LoadTy);
+    // For scalable vectors, check the known minimum size is a power of 2.
+    Check(Size.getKnownMinValue() > 0 && isPowerOf2_64(Size.getKnownMinValue()),
+          "llvm.speculative.load type must have a power-of-2 size", &Call);
+
+    unsigned NumArgs = Call.arg_size();
+    Check(NumArgs >= 3, "llvm.speculative.load requires at least 3 arguments",
+          &Call);
+
+    Value *PayloadArg = Call.getArgOperand(2);
+    if (PayloadArg->getType()->isIntegerTy(64)) {
+      // Direct form: (ptr, i1 from_end, i64 num_accessible_bytes)
+      Check(NumArgs == 3,
+            "llvm.speculative.load direct form has too many arguments", &Call);
+      if (auto *CI = dyn_cast<ConstantInt>(PayloadArg)) {
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nikic wrote:

Can't verify non-immarg constants, it will introduce errors due to constant propagation.

https://github.com/llvm/llvm-project/pull/179642