[AMDGPU] Add verification for amdgcn.init.exec.from.input (llvm#128172)

Check that the input register is an inreg argument to the parent
function. (See the comment in `IntrinsicsAMDGPU.td`.)

This LLVM defect was identified via the AMD Fuzzing project.

---------

Co-authored-by: Matt Arsenault <[email protected]>

Author: ro-i

llvm/lib/IR/Verifier.cpp

@@ -6371,6 +6371,14 @@ void Verifier::visitIntrinsicCall(Intrinsic::ID ID, CallBase &Call) {
           "llvm.amdgcn.cs.chain must be followed by unreachable", &Call);
     break;
   }
+  case Intrinsic::amdgcn_init_exec_from_input: {
+    const Argument *Arg = dyn_cast<Argument>(Call.getOperand(0));
+    Check(Arg && Arg->hasInRegAttr(),
+          "only inreg arguments to the parent function are valid as inputs to "
+          "this intrinsic",
+          &Call);
+    break;
+  }
   case Intrinsic::amdgcn_set_inactive_chain_arg: {
     auto CallerCC = Call.getCaller()->getCallingConv();
     switch (CallerCC) {

llvm/test/Verifier/AMDGPU/intrinsic-amdgpu-init-exec-from-input.ll

@@ -0,0 +1,25 @@
+; RUN: not llvm-as -disable-output 2>&1 %s | FileCheck %s
+
+declare void @llvm.amdgcn.init.exec.from.input(i32, i32 immarg)
+
+; CHECK: only inreg arguments to the parent function are valid as inputs to this intrinsic
+; CHECK-NEXT: call void @llvm.amdgcn.init.exec.from.input(i32 0, i32 0)
+define void @init_exec_from_input_fail_constant() {
+  call void @llvm.amdgcn.init.exec.from.input(i32 0, i32 0)
+  ret void
+}
+
+; CHECK: only inreg arguments to the parent function are valid as inputs to this intrinsic
+; CHECK-NEXT: call void @llvm.amdgcn.init.exec.from.input(i32 %b, i32 0)
+define void @init_exec_from_input_fail_not_inreg(i32 inreg %a, i32 %b) {
+  call void @llvm.amdgcn.init.exec.from.input(i32 %b, i32 0)
+  ret void
+}
+
+; CHECK: only inreg arguments to the parent function are valid as inputs to this intrinsic
+; CHECK-NEXT: call void @llvm.amdgcn.init.exec.from.input(i32 %c, i32 0)
+define void @init_exec_from_input_fail_instruction(i32 inreg %a, i32 %b) {
+  %c = add i32 %a, %b
+  call void @llvm.amdgcn.init.exec.from.input(i32 %c, i32 0)
+  ret void
+}