[DirectX] add Function name to DiagnosticInfoUnsupported Msg in DXILOpLowering

fixes llvm#135654

In llvm#128613 we added safe guards to prevent the lowering of just any intrinsic in the backend. We used `DiagnosticInfoUnsupported` to do this.

What we found was when using `opt` the diagnostic print function  was called but when using clang the diagnostic message was used.

Printing message in the clang version means we miss valuable debugging information like function name and function type when LLVMContext was only needed to call `getBestLocationFromDebugLoc`.

There are a few potential fixes

1. Write a custom DiagnosticInfoUnsupported so we can change the Message
   just for DirectX. Too heavy handed so rejected.

2. Add the function name to the Message in DirectX code. Very simple one
   line change. Downside is
   when using opt you see the function name twice. But makes the
   clang-dxc bugs more actionable.

3. change CodeGenAction.cpp to always use the print function and not the
   message directly. Downside is a bunch of innacurate information shows
   up in the message if you don't  specify
   `-debug-info-kind=standalone`.

4. add some book keeping to know which function called the intrinsic
   keep a map of these so we can pass the calling function to
   `DiagnosticInfoUnsupported` instead of the intrinsic.
   This would only be useful if we had debug info so we could
   distinguish different uses of the intrinsic. We would also need to
   change from iterating on every function to doing somethin like a
   LazyCallGraph.

5. pick a different means of doing a Diagnostic error, because other
   uses of`DiagnosticInfoUnsupported` error when we are in the body of a
   function not when we see one being used like in the intrinsic case.

This PR went with option 2. Its low code change that also only impacts
the DirectX backend.

Author: farzonl

clang/test/CodeGenDirectX/unsupported_intrinsic.hlsl

@@ -0,0 +1,7 @@
+// RUN: %if clang-dxc %{not %clang_dxc -T lib_6_3 %s 2>&1 | FileCheck %s %}
+
+// CHECK: error: Unsupported intrinsic llvm.vector.reduce.and.v4i32 for DXIL lowering
+
+export int vecReduceAndTest(int4 vec) {
+    return __builtin_reduce_and(vec);
+}

llvm/lib/Target/DirectX/DXILOpLowering.cpp

@@ -8,7 +8,6 @@
 
 #include "DXILOpLowering.h"
 #include "DXILConstants.h"
-#include "DXILIntrinsicExpansion.h"
 #include "DXILOpBuilder.h"
 #include "DXILShaderFlags.h"
 #include "DirectX.h"
@@ -27,6 +26,7 @@
 #include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/FormatVariadic.h"
 
 #define DEBUG_TYPE "dxil-op-lower"
 
@@ -756,8 +756,11 @@ class OpLowerer {
       case Intrinsic::not_intrinsic:
         continue;
       default: {
-        DiagnosticInfoUnsupported Diag(
-            F, "Unsupported intrinsic for DXIL lowering");
+        std::string Msg =
+            llvm::formatv("Unsupported intrinsic {0} for DXIL lowering",
+                          F.getName())
+                .str();
+        DiagnosticInfoUnsupported Diag(F, Msg);
         M.getContext().diagnose(Diag);
         HasErrors |= true;
         break;

llvm/test/CodeGen/DirectX/unsupported_intrinsic.ll

@@ -1,6 +1,6 @@
 ; RUN: not opt -S -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>): Unsupported intrinsic for DXIL lowering
+; CHECK: Unsupported intrinsic llvm.vector.reduce.and.v4i32 for DXIL lowering
 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