Add base vertex and base instance system values (#5918)

* Add base vertex and base instance system values

* Fixed incorrect stage in tests

1 files changed, 10 insertions, 0 deletions

diff --git a/source/slang/slang-emit-spirv.cpp b/source/slang/slang-emit-spirv.cpp
index 63ebfcf6e..51ff9066c 100644
--- a/source/slang/slang-emit-spirv.cpp
+++ b/source/slang/slang-emit-spirv.cpp
@@ -5303,6 +5303,16 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
                             SpvBuiltInShadingRateKHR,
                             inst);
                 }
+                else if (semanticName == "sv_startvertexlocation")
+                {
+                    requireSPIRVCapability(SpvCapabilityDrawParameters);
+                    return getBuiltinGlobalVar(inst->getFullType(), SpvBuiltInBaseVertex, inst);
+                }
+                else if (semanticName == "sv_startinstancelocation")
+                {
+                    requireSPIRVCapability(SpvCapabilityDrawParameters);
+                    return getBuiltinGlobalVar(inst->getFullType(), SpvBuiltInBaseInstance, inst);
+                }
                 SLANG_UNREACHABLE("Unimplemented system value in spirv emit.");
             }
         }