Parser: Fix OpCompositeConstruct with OpUndef.

Just treat any undefined argument as 0. It is risky to use the undefined
variable as it might not lower to a true constant.

1 files changed, 8 insertions, 0 deletions

diff --git a/spirv_parser.cpp b/spirv_parser.cpp
index f5ca7dfc..fa87fa37 100644
--- a/spirv_parser.cpp
+++ b/spirv_parser.cpp
@@ -775,6 +775,7 @@ void Parser::parse(const Instruction &instruction)
 				// We do not know their value, so any attempt to query SPIRConstant later
 				// will fail. We can only propagate the ID of the expression and use to_expression on it.
 				auto *constant_op = maybe_get<SPIRConstantOp>(ops[2 + i]);
+				auto *undef_op = maybe_get<SPIRUndef>(ops[2 + i]);
 				if (constant_op)
 				{
 					if (op == OpConstantComposite)
@@ -786,6 +787,13 @@ void Parser::parse(const Instruction &instruction)
 					remapped_constant_ops[i].specialization = true;
 					c[i] = &remapped_constant_ops[i];
 				}
+				else if (undef_op)
+				{
+					// Undefined, just pick 0.
+					remapped_constant_ops[i].make_null(get<SPIRType>(undef_op->basetype));
+					remapped_constant_ops[i].constant_type = undef_op->basetype;
+					c[i] = &remapped_constant_ops[i];
+				}
 				else
 					c[i] = &get<SPIRConstant>(ops[2 + i]);
 			}