[llvm-branch-commits] [clang] [llvm] [HLSL][RootSignature] Add parsing infastructure for StaticSampler (PR #140180)

[Sarah Spall via llvm-branch-commits]

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@@ -606,6 +644,30 @@ RootSignatureParser::parseDescriptorTableClauseParams(TokenKind RegType) {
   return Params;
 }
 
+std::optional<RootSignatureParser::ParsedStaticSamplerParams>
+RootSignatureParser::parseStaticSamplerParams() {
+  assert(CurToken.TokKind == TokenKind::pu_l_paren &&
+         "Expects to only be invoked starting at given token");
+
+  ParsedStaticSamplerParams Params;
+  do {
+    // `s` POS_INT
+    if (tryConsumeExpectedToken(TokenKind::sReg)) {
+      if (Params.Reg.has_value()) {
+        getDiags().Report(CurToken.TokLoc, diag::err_hlsl_rootsig_repeat_param)
+            << CurToken.TokKind;
+        return std::nullopt;
+      }
+      auto Reg = parseRegister();
+      if (!Reg.has_value())
+        return std::nullopt;
+      Params.Reg = Reg;
+    }
+  } while (tryConsumeExpectedToken(TokenKind::pu_comma));
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spall wrote:

It looks like this parsing code allows stuff of the form 'StaticSampler(,,,,,,,,,,,,,,,,,)', and from looking at a DXC example it seems that is allowed https://godbolt.org/z/j7qP11h9W. It is amusing this is so permissive, and I wonder if there is a reason for that. 

https://github.com/llvm/llvm-project/pull/140180