Instrument: Change output buffer offset definitions (#4961)

Add a flags field at the first offset within this buffer.
Define flags to allow buffer OOB checking to be enabled or
disabled at run time. This is to support VK_EXT_pipeline_robustnes.

1 files changed, 13 insertions, 4 deletions

diff --git a/include/spirv-tools/instrument.hpp b/include/spirv-tools/instrument.hpp
index a19491fd3..a75561b50 100644
--- a/include/spirv-tools/instrument.hpp
+++ b/include/spirv-tools/instrument.hpp
@@ -36,16 +36,25 @@ namespace spvtools {
 // generated by InstrumentPass::GenDebugStreamWrite. This method is utilized
 // by InstBindlessCheckPass, InstBuffAddrCheckPass, and InstDebugPrintfPass.
 //
-// The first member of the debug output buffer contains the next available word
+// The 1st member of the debug output buffer contains a set of flags
+// controlling the behavior of instrumentation code.
+static const int kDebugOutputFlagsOffset = 0;
+
+// Values stored at kDebugOutputFlagsOffset
+enum kInstFlags : unsigned int {
+  kInstBufferOOBEnable = 0x1,
+};
+
+// The 2nd member of the debug output buffer contains the next available word
 // in the data stream to be written. Shaders will atomically read and update
 // this value so as not to overwrite each others records. This value must be
 // initialized to zero
-static const int kDebugOutputSizeOffset = 0;
+static const int kDebugOutputSizeOffset = 1;
 
-// The second member of the output buffer is the start of the stream of records
+// The 3rd member of the output buffer is the start of the stream of records
 // written by the instrumented shaders. Each record represents a validation
 // error. The format of the records is documented below.
-static const int kDebugOutputDataOffset = 1;
+static const int kDebugOutputDataOffset = 2;
 
 // Common Stream Record Offsets
 //