[HLSL] Add validation for the -enable-16bit-types option (#85340)

Previously, the clang compiler with the dxc driver would accept the
-enable-16bit-types flag without checking to see if the required
conditions are met for proper processing of the flag.
Specifically, -enable-16bit-types requires a shader model of at least
6.2 and an HLSL version of at least 2021.
This PR adds a validation check for these other options having the
required values, and emits an error if these constraints are not met.
Fixes #57876

---------

Co-authored-by: Damyan Pepper <[email protected]>
Co-authored-by: Chris B <[email protected]>

Author: 3 people

clang/include/clang/Basic/DiagnosticDriverKinds.td

@@ -753,7 +753,8 @@ def err_drv_hlsl_unsupported_target : Error<
   "HLSL code generation is unsupported for target '%0'">;
 def err_drv_hlsl_bad_shader_required_in_target : Error<
   "%select{shader model|Vulkan environment|shader stage}0 is required as %select{OS|environment}1 in target '%2' for HLSL code generation">;
-
+def err_drv_hlsl_16bit_types_unsupported: Error<
+  "'%0' option requires target HLSL Version >= 2018%select{| and shader model >= 6.2}1, but HLSL Version is '%2'%select{| and shader model is '%3'}1">;
 def err_drv_hlsl_bad_shader_unsupported : Error<
   "%select{shader model|Vulkan environment|shader stage}0 '%1' in target '%2' is invalid for HLSL code generation">;
 def warn_drv_dxc_missing_dxv : Warning<"dxv not found. "

clang/lib/Driver/ToolChains/HLSL.cpp

@@ -255,9 +255,7 @@ HLSLToolChain::TranslateArgs(const DerivedArgList &Args, StringRef BoundArch,
   if (!DAL->hasArg(options::OPT_O_Group)) {
     DAL->AddJoinedArg(nullptr, Opts.getOption(options::OPT_O), "3");
   }
-  // FIXME: add validation for enable_16bit_types should be after HLSL 2018 and
-  // shader model 6.2.
-  // See: https://github.com/llvm/llvm-project/issues/57876
+
   return DAL;
 }
 

clang/lib/Frontend/CompilerInvocation.cpp

@@ -4284,11 +4284,30 @@ bool CompilerInvocation::ParseLangArgs(LangOptions &Opts, ArgList &Args,
           Diags.Report(diag::err_drv_hlsl_bad_shader_unsupported)
               << ShaderModel << T.getOSName() << T.str();
         }
+        // Validate that if fnative-half-type is given, that
+        // the language standard is at least hlsl2018, and that
+        // the target shader model is at least 6.2.
+        if (Args.getLastArg(OPT_fnative_half_type)) {
+          const LangStandard &Std =
+              LangStandard::getLangStandardForKind(Opts.LangStd);
+          if (!(Opts.LangStd >= LangStandard::lang_hlsl2018 &&
+                T.getOSVersion() >= VersionTuple(6, 2)))
+            Diags.Report(diag::err_drv_hlsl_16bit_types_unsupported)
+                << "-enable-16bit-types" << true << Std.getName()
+                << T.getOSVersion().getAsString();
+        }
       } else if (T.isSPIRVLogical()) {
         if (!T.isVulkanOS() || T.getVulkanVersion() == VersionTuple(0)) {
           Diags.Report(diag::err_drv_hlsl_bad_shader_unsupported)
               << VulkanEnv << T.getOSName() << T.str();
         }
+        if (Args.getLastArg(OPT_fnative_half_type)) {
+          const LangStandard &Std =
+              LangStandard::getLangStandardForKind(Opts.LangStd);
+          if (!(Opts.LangStd >= LangStandard::lang_hlsl2018))
+            Diags.Report(diag::err_drv_hlsl_16bit_types_unsupported)
+                << "-fnative-half-type" << false << Std.getName();
+        }
       } else {
         llvm_unreachable("expected DXIL or SPIR-V target");
       }

clang/test/CodeGenHLSL/builtins/RWBuffer-elementtype.hlsl

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.0-compute -finclude-default-header -fnative-half-type -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.2-compute -finclude-default-header -fnative-half-type -emit-llvm -o - %s | FileCheck %s
 
 RWBuffer<int16_t> BufI16;
 RWBuffer<uint16_t> BufU16;

clang/test/Options/enable_16bit_types_validation.hlsl

@@ -0,0 +1,25 @@
+// RUN: not %clang_dxc -enable-16bit-types -T cs_6_0 -HV 2016 %s 2>&1  | FileCheck -check-prefix=both_invalid %s
+// RUN: not %clang_dxc -enable-16bit-types -T lib_6_4 -HV 2017 %s 2>&1 | FileCheck -check-prefix=HV_invalid_2017 %s
+// RUN: not %clang_dxc -enable-16bit-types -T cs_6_0 /HV 2021 %s 2>&1  | FileCheck -check-prefix=TP_invalid %s
+// RUN: %clang_dxc -enable-16bit-types -T lib_6_4 /HV 2018 %s 2>&1 -###   | FileCheck -check-prefix=valid_2018 %s
+// RUN: %clang_dxc -enable-16bit-types -T lib_6_4 /HV 2021 %s 2>&1 -###   | FileCheck -check-prefix=valid_2021 %s
+
+
+// both_invalid: error: '-enable-16bit-types' option requires target HLSL Version >= 2018 and shader model >= 6.2, but HLSL Version is 'hlsl2016' and shader model is '6.0'
+// HV_invalid_2017: error: '-enable-16bit-types' option requires target HLSL Version >= 2018 and shader model >= 6.2, but HLSL Version is 'hlsl2017' and shader model is '6.4'
+// TP_invalid: error: '-enable-16bit-types' option requires target HLSL Version >= 2018 and shader model >= 6.2, but HLSL Version is 'hlsl2021' and shader model is '6.0'
+
+// valid_2021: "dxil-unknown-shadermodel6.4-library"
+// valid_2021-SAME: "-std=hlsl2021"
+// valid_2021-SAME: "-fnative-half-type"
+
+// valid_2018: "dxil-unknown-shadermodel6.4-library"
+// valid_2018-SAME: "-std=hlsl2018"
+// valid_2018-SAME: "-fnative-half-type"
+
+[numthreads(1,1,1)]
+void main()
+{
+  return;
+}
+

clang/test/Options/enable_16bit_types_validation_spirv.hlsl

@@ -0,0 +1,14 @@
+// RUN: not %clang_cc1 -internal-isystem D:\llvm-project\build\x64-Release\lib\clang\19\include -nostdsysteminc -triple spirv-vulkan-library -x hlsl -std=hlsl2016 -fnative-half-type -emit-llvm -disable-llvm-passes  -o - %s 2>&1 | FileCheck %s --check-prefix=SPIRV
+// RUN: %clang_cc1 -internal-isystem D:\llvm-project\build\x64-Release\lib\clang\19\include -nostdsysteminc -triple spirv-vulkan-library -x hlsl -std=hlsl2021 -fnative-half-type -emit-llvm -disable-llvm-passes  -o - %s 2>&1 | FileCheck %s --check-prefix=valid
+
+// SPIRV: error: '-fnative-half-type' option requires target HLSL Version >= 2018, but HLSL Version is 'hlsl2016'
+
+// valid: "spirv-unknown-vulkan-library"
+// valid: define spir_func void @main() #0 {
+
+[numthreads(1,1,1)]
+void main()
+{
+  return;
+}
+