[HLSL][Driver] Make vk1.3 the default.

[s-perron]

The HLSL driver currently defaults the triple to an unversioned os and
subarch when targeting SPIR-V. This means the SPIR-V backend decides the
default value. That is not a great option because a change the backend
could cause a change in Clang.

Now that we want to choose the default we need to consider the best
option. DXC currently defaults to Vulkan1.0. We are planning on not
supporting Vulkan1.0 in the Clang HLSL compiler because it is newer
versions of Vulkan are commonly supported on nearly all hardware, so
users do not use it.

Since we have to change from DXC anyway, we are using VK1.3. It has been
out long enough to be commonly available, and the initial implementation
of SPIR-V features for HLSL are assuming Vulkan 1.3.

[llvmbot]

@llvm/pr-subscribers-clang-driver

@llvm/pr-subscribers-clang

Author: Steven Perron (s-perron)

Changes

The HLSL driver currently defaults the triple to an unversioned os and
subarch when targeting SPIR-V. This means the SPIR-V backend decides the
default value. That is not a great option because a change the backend
could cause a change in Clang.

Now that we want to choose the default we need to consider the best
option. DXC currently defaults to Vulkan1.0. We are planning on not
supporting Vulkan1.0 in the Clang HLSL compiler because it is newer
versions of Vulkan are commonly supported on nearly all hardware, so
users do not use it.

Since we have to change from DXC anyway, we are using VK1.3. It has been
out long enough to be commonly available, and the initial implementation
of SPIR-V features for HLSL are assuming Vulkan 1.3.

---

Full diff: https://github.com/llvm/llvm-project/pull/143384.diff

2 Files Affected:

• (modified) clang/lib/Driver/Driver.cpp (+12-14)
• (modified) clang/test/Driver/dxc_spirv.hlsl (+1-1)

diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 73ff7757c3b04..af0c4f2012f30 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -1596,28 +1596,26 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
       A->claim();
 
       if (Args.hasArg(options::OPT_spirv)) {
+        const llvm::StringMap<llvm::Triple::SubArchType> ValidTargets = {
+            {"vulkan1.2", llvm::Triple::SPIRVSubArch_v15},
+            {"vulkan1.3", llvm::Triple::SPIRVSubArch_v16}};
         llvm::Triple T(TargetTriple);
-        T.setArch(llvm::Triple::spirv);
-        T.setOS(llvm::Triple::Vulkan);
 
-        // Set specific Vulkan version if applicable.
+        // Set specific Vulkan version. Default to vulkan1.3.
+        auto TargetInfo = ValidTargets.find("vulkan1.3");
         if (const Arg *A = Args.getLastArg(options::OPT_fspv_target_env_EQ)) {
-          const llvm::StringMap<llvm::Triple::SubArchType> ValidTargets = {
-              {"vulkan1.2", llvm::Triple::SPIRVSubArch_v15},
-              {"vulkan1.3", llvm::Triple::SPIRVSubArch_v16}};
-
-          auto TargetInfo = ValidTargets.find(A->getValue());
-          if (TargetInfo != ValidTargets.end()) {
-            T.setOSName(TargetInfo->getKey());
-            T.setArch(llvm::Triple::spirv, TargetInfo->getValue());
-          } else {
+          TargetInfo = ValidTargets.find(A->getValue());
+          if (TargetInfo == ValidTargets.end()) {
             Diag(diag::err_drv_invalid_value)
                 << A->getAsString(Args) << A->getValue();
           }
           A->claim();
         }
-
-        TargetTriple = T.str();
+        if (TargetInfo != ValidTargets.end()) {
+          T.setOSName(TargetInfo->getKey());
+          T.setArch(llvm::Triple::spirv, TargetInfo->getValue());
+          TargetTriple = T.str();
+        }
       }
     } else {
       Diag(diag::err_drv_dxc_missing_target_profile);
diff --git a/clang/test/Driver/dxc_spirv.hlsl b/clang/test/Driver/dxc_spirv.hlsl
index e6624e5f1b3f6..65c9018dc54c5 100644
--- a/clang/test/Driver/dxc_spirv.hlsl
+++ b/clang/test/Driver/dxc_spirv.hlsl
@@ -3,7 +3,7 @@
 // RUN: %clang_dxc -T cs_6_0 -spirv -fspv-target-env=vulkan1.3 -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-VULKAN13
 // RUN: not %clang_dxc -T cs_6_0 -spirv -fspv-target-env=vulkan1.0 -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-ERROR
 
-// CHECK: "-triple" "spirv-unknown-vulkan-compute"
+// CHECK: "-triple" "spirv1.6-unknown-vulkan1.3-compute"
 // CHECK-SAME: "-x" "hlsl"
 
 // CHECK-VULKAN12: "-triple" "spirv1.5-unknown-vulkan1.2-compute"

[Keenuts]

a nit, otherwise LGTM