[llvm] [SPIR-V] Add Vertex execution model (PR #142369)

[Nathan Gauër via llvm-commits]

https://github.com/Keenuts created https://github.com/llvm/llvm-project/pull/142369

Adds backend handling of the vertex shader type compiling from HLSL.

>From 2f263fa1687d8ccb344e0a2d372567c270a849b3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Nathan=20Gau=C3=ABr?= <brioche at google.com>
Date: Mon, 2 Jun 2025 13:31:11 +0200
Subject: [PATCH] [SPIR-V] Add Vertex execution model

Adds backend handling of the vertex shader type compiling from HLSL.
---
 llvm/lib/Target/SPIRV/SPIRVCallLowering.cpp     |  2 ++
 llvm/test/CodeGen/SPIRV/ExecutionMode_Vertex.ll | 12 ++++++++++++
 2 files changed, 14 insertions(+)
 create mode 100644 llvm/test/CodeGen/SPIRV/ExecutionMode_Vertex.ll

diff --git a/llvm/lib/Target/SPIRV/SPIRVCallLowering.cpp b/llvm/lib/Target/SPIRV/SPIRVCallLowering.cpp
index 5991a9af6364d..147cf7e8a2002 100644
--- a/llvm/lib/Target/SPIRV/SPIRVCallLowering.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVCallLowering.cpp
@@ -279,6 +279,8 @@ getExecutionModel(const SPIRVSubtarget &STI, const Function &F) {
   const auto value = attribute.getValueAsString();
   if (value == "compute")
     return SPIRV::ExecutionModel::GLCompute;
+  if (value == "vertex")
+    return SPIRV::ExecutionModel::Vertex;
 
   report_fatal_error("This HLSL entry point is not supported by this backend.");
 }
diff --git a/llvm/test/CodeGen/SPIRV/ExecutionMode_Vertex.ll b/llvm/test/CodeGen/SPIRV/ExecutionMode_Vertex.ll
new file mode 100644
index 0000000000000..19bba23b437fd
--- /dev/null
+++ b/llvm/test/CodeGen/SPIRV/ExecutionMode_Vertex.ll
@@ -0,0 +1,12 @@
+; RUN: llc -O0 -mtriple=spirv-unknown-vulkan1.3-vertex %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv-unknown-vulkan1.3-vertex %s -o - -filetype=obj | spirv-val %}
+
+; CHECK: OpCapability Shader
+; CHECK: OpEntryPoint Vertex %[[#entry:]] "main"
+
+define void @main() #1 {
+entry:
+  ret void
+}
+
+attributes #1 = { "hlsl.shader"="vertex" }