[HLSL] Explicitly set the SPIR-V version with spv-target-env

In DXC, setting the vulkan version automatically sets the target spir-v
version to the maximum spir-v version that the vulkan version must
support. So for Vulkan 1.2, we set the spir-v version to spirv 1.5
because every implementation of Vulkan 1.2 must support spirv 1.5, but
not spir-v 1.6.

Author: s-perron

clang/lib/Driver/Driver.cpp

@@ -1468,9 +1468,14 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
 
         // Set specific Vulkan version if applicable.
         if (const Arg *A = Args.getLastArg(options::OPT_fspv_target_env_EQ)) {
-          const llvm::StringSet<> ValidValues = {"vulkan1.2", "vulkan1.3"};
-          if (ValidValues.contains(A->getValue())) {
-            T.setOSName(A->getValue());
+          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 {
             Diag(diag::err_drv_invalid_value)
                 << A->getAsString(Args) << A->getValue();

clang/test/Driver/dxc_spirv.hlsl

@@ -6,8 +6,8 @@
 // CHECK: "-triple" "spirv-unknown-vulkan-compute"
 // CHECK-SAME: "-x" "hlsl"
 
-// CHECK-VULKAN12: "-triple" "spirv-unknown-vulkan1.2-compute"
+// CHECK-VULKAN12: "-triple" "spirv1.5-unknown-vulkan1.2-compute"
 
-// CHECK-VULKAN13: "-triple" "spirv-unknown-vulkan1.3-compute"
+// CHECK-VULKAN13: "-triple" "spirv1.6-unknown-vulkan1.3-compute"
 
 // CHECK-ERROR: error: invalid value 'vulkan1.0' in '-fspv-target-env=vulkan1.0'

llvm/lib/TargetParser/Triple.cpp

@@ -113,6 +113,26 @@ StringRef Triple::getArchName(ArchType Kind, SubArchType SubArch) {
     if (SubArch == AArch64SubArch_arm64e)
       return "arm64e";
     break;
+  case Triple::spirv:
+    switch (SubArch) {
+    case Triple::SPIRVSubArch_v10:
+      return "spirv1.0";
+    case Triple::SPIRVSubArch_v11:
+      return "spirv1.1";
+    case Triple::SPIRVSubArch_v12:
+      return "spirv1.2";
+    case Triple::SPIRVSubArch_v13:
+      return "spirv1.3";
+    case Triple::SPIRVSubArch_v14:
+      return "spirv1.4";
+    case Triple::SPIRVSubArch_v15:
+      return "spirv1.5";
+    case Triple::SPIRVSubArch_v16:
+      return "spirv1.6";
+    default:
+      break;
+    }
+    break;
   case Triple::dxil:
     switch (SubArch) {
     case Triple::NoSubArch: