[llvm] [DirectX] only allow intrinsics defined in DXIL.td (PR #128613)

[Farzon Lotfi via llvm-commits]

https://github.com/farzonl created https://github.com/llvm/llvm-project/pull/128613

Fixes #128071
The current behavior lets intrinsics that don't map to a DXILOP slip through. Nothing catches this until we hit the DXIL validator. This change fails earlier so we don't encode invalid llvm intrinsics that can slip through because of clang builtins like `__builtin_reduce_and`
example:
https://hlsl.godbolt.org/z/13rPj18vn

>From 69f029514a5cde4c6a6303bc3d3e11c2f554f89f Mon Sep 17 00:00:00 2001
From: Farzon Lotfi <farzonlotfi at microsoft.com>
Date: Mon, 24 Feb 2025 20:11:26 -0500
Subject: [PATCH] [DirectX] only allow intrinsics defined in DXIL.td Fixes
 #128071 The current behavior lets intrinsics that don't map to a DXILOP slip
 through. Nothing catches this until we hit the DXIL validator. This change
 fails earlier so we don't encode invalid llvm intrinsics that can slip
 through because of clang builtins like `__builtin_reduce_and` example:
 https://hlsl.godbolt.org/z/13rPj18vn

---
 llvm/lib/Target/DirectX/DXILOpLowering.cpp     |  7 +++++--
 llvm/test/CodeGen/DirectX/unknown_intrinsic.ll | 11 +++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)
 create mode 100644 llvm/test/CodeGen/DirectX/unknown_intrinsic.ll

diff --git a/llvm/lib/Target/DirectX/DXILOpLowering.cpp b/llvm/lib/Target/DirectX/DXILOpLowering.cpp
index 83cc4b18824c7..a98107a71c219 100644
--- a/llvm/lib/Target/DirectX/DXILOpLowering.cpp
+++ b/llvm/lib/Target/DirectX/DXILOpLowering.cpp
@@ -770,8 +770,11 @@ class OpLowerer {
         continue;
       Intrinsic::ID ID = F.getIntrinsicID();
       switch (ID) {
-      default:
-        continue;
+      default: {
+        DiagnosticInfoUnsupported Diag(F, "Unknown intrinsic?");
+        M.getContext().diagnose(Diag);
+        break;
+      }
 #define DXIL_OP_INTRINSIC(OpCode, Intrin, ...)                                 \
   case Intrin:                                                                 \
     HasErrors |= replaceFunctionWithOp(                                        \
diff --git a/llvm/test/CodeGen/DirectX/unknown_intrinsic.ll b/llvm/test/CodeGen/DirectX/unknown_intrinsic.ll
new file mode 100644
index 0000000000000..efd0c5637077e
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/unknown_intrinsic.ll
@@ -0,0 +1,11 @@
+; RUN: not opt -S -scalarizer -dxil-op-lower -mtriple=dxil-pc-shadermodel6.3-library %s 2>&1 | FileCheck %s
+
+; CHECK: error: <unknown>:0:0: in function llvm.vector.reduce.and.v4i32 i32 (<4 x i32>): Unknown intrinsic?
+define i32 @fn_and(<4 x i32> %0) local_unnamed_addr #0 {
+  %2 = tail call i32 @llvm.vector.reduce.and.v4i32(<4 x i32> %0)
+  ret i32 %2
+}
+
+declare i32 @llvm.vector.reduce.and.v4i32(<4 x i32>)
+
+attributes #0 = { convergent norecurse nounwind "hlsl.export"}