Allow up to v1.2 SPIR-V features + chipStar Extensions

This is to support warp-level primitives (shuffles, ballots) via
extensions. The non-extension ones would require v1.3, but it's
not supported by any target yet.

Allow limited debug info

Allow debug info kind that is compatible with llvm-spirv, that is, it
is limited to a kind with an intent to avoid emitting DW_OP_LLVM_<op>
expressions.

Disable SPIR-V extensions except ones needed by chipStar

Author: pjaaskel

clang/lib/Driver/ToolChains/HIPSPV.cpp

@@ -96,9 +96,21 @@ void HIPSPV::Linker::constructLinkAndEmitSpirvCommand(
   }
 
   // Emit SPIR-V binary.
-
-  llvm::opt::ArgStringList TrArgs{"--spirv-max-version=1.1",
-                                  "--spirv-ext=+all"};
+  // We need 1.2 when using warp-level primitivies via sub group extensions.
+  // Strictly put we'd need 1.3 for the standard non-extension shuffle
+  // operations, but it's not supported by any target yet.
+  llvm::opt::ArgStringList TrArgs{
+      "--spirv-max-version=1.2",
+      "--spirv-ext=-all"
+
+      // TODO: Consider upstreaming -Xspirv-translator found in intel-llvm
+      //       repository and make it work for SPIR-V toolchains so chipStar may
+      //       control extensions it needs (if/when necessary).
+
+      // Needed for experimental indirect call support.
+      ",+SPV_INTEL_function_pointers"
+      // Needed for shuffles below SPIR-V 1.3
+      ",+SPV_INTEL_subgroups"};
   InputInfo TrInput = InputInfo(types::TY_LLVM_BC, TempFile, "");
   SPIRV::constructTranslateCommand(C, *this, JA, Output, TrInput, TrArgs);
 }
@@ -285,8 +297,8 @@ VersionTuple HIPSPVToolChain::computeMSVCVersion(const Driver *D,
 void HIPSPVToolChain::adjustDebugInfoKind(
     codegenoptions::DebugInfoKind &DebugInfoKind,
     const llvm::opt::ArgList &Args) const {
-  // Debug info generation is disabled for SPIRV-LLVM-Translator
-  // which currently aborts on the presence of DW_OP_LLVM_convert.
-  // TODO: Enable debug info when the SPIR-V backend arrives.
-  DebugInfoKind = codegenoptions::NoDebugInfo;
+
+  // Restrict the debug info to a kind compatible with llvm-spirv.
+  if (DebugInfoKind > codegenoptions::DebugLineTablesOnly)
+    DebugInfoKind = codegenoptions::DebugLineTablesOnly;
 }