Revert "[Verifier] Reject va_start in non-variadic function (#88809)"

This reverts commit 61717c1. Failed a MLIR test

Author: JonChesterfield

llvm/lib/Analysis/Lint.cpp

@@ -350,7 +350,10 @@ void Lint::visitCallBase(CallBase &I) {
     }
 
     case Intrinsic::vastart:
-      // vastart in non-varargs function is rejected by the verifier
+      Check(I.getParent()->getParent()->isVarArg(),
+            "Undefined behavior: va_start called in a non-varargs function",
+            &I);
+
       visitMemoryReference(I, MemoryLocation::getForArgument(&I, 0, TLI),
                            std::nullopt, nullptr, MemRef::Read | MemRef::Write);
       break;

llvm/lib/IR/Verifier.cpp

@@ -5798,11 +5798,6 @@ void Verifier::visitIntrinsicCall(Intrinsic::ID ID, CallBase &Call) {
 
     break;
   }
-  case Intrinsic::vastart: {
-    Check(Call.getFunction()->isVarArg(),
-          "va_start called in a non-varargs function");
-    break;
-  }
   case Intrinsic::vector_reduce_and:
   case Intrinsic::vector_reduce_or:
   case Intrinsic::vector_reduce_xor:

llvm/test/CodeGen/AArch64/GlobalISel/vastart.ll

@@ -3,7 +3,7 @@
 
 
 declare void @llvm.va_start(ptr)
-define void @test_va_start(ptr %list, ...) {
+define void @test_va_start(ptr %list) {
 ; CHECK-LABEL: name: test_va_start
 ; CHECK: [[LIST:%[0-9]+]]:_(p0) = COPY $x0
 ; CHECK-IOS: G_VASTART [[LIST]](p0) :: (store (s64) into %ir.list, align 1)

llvm/test/Other/lint.ll

@@ -124,6 +124,13 @@ define void @0() nounwind {
   ret void
 }
 
+; CHECK: va_start called in a non-varargs function
+declare void @llvm.va_start(ptr)
+define void @not_vararg(ptr %p) nounwind {
+  call void @llvm.va_start(ptr %p)
+  ret void
+}
+
 ; CHECK: Undefined behavior: Branch to non-blockaddress
 define void @use_indbr() {
   indirectbr ptr @foo, [label %block]