Refactor out access chain reads.

Prepare for matrix, array and struct loads.

spirv_hlsl.cpp

@@ -17,6 +17,7 @@
 #include "spirv_hlsl.hpp"
 #include "GLSL.std.450.h"
 #include <algorithm>
+#include <assert.h>
 
 using namespace spv;
 using namespace spirv_cross;
@@ -1849,17 +1850,9 @@ void CompilerHLSL::emit_glsl_op(uint32_t result_type, uint32_t id, uint32_t eop,
 	}
 }
 
-void CompilerHLSL::emit_load(const Instruction &instruction)
+string CompilerHLSL::read_access_chain(const SPIRAccessChain &chain)
 {
-	auto ops = stream(instruction);
+	auto &type = get<SPIRType>(chain.basetype);
-
-	auto *chain = maybe_get<SPIRAccessChain>(ops[2]);
-	if (chain)
-	{
-		auto &type = get<SPIRType>(chain->basetype);
-		uint32_t result_type = ops[0];
-		uint32_t id = ops[1];
-		uint32_t ptr = ops[2];
 
 	SPIRType target_type;
 	target_type.basetype = SPIRType::UInt;
@@ -1892,11 +1885,27 @@ void CompilerHLSL::emit_load(const Instruction &instruction)
 		SPIRV_CROSS_THROW("Unknown vector size.");
 	}
 
-		auto load_expr = join(chain->base, ".", load_op, "(", chain->dynamic_index, chain->static_index, ")");
+	auto load_expr = join(chain.base, ".", load_op, "(", chain.dynamic_index, chain.static_index, ")");
 	auto bitcast_op = bitcast_glsl_op(type, target_type);
 	if (!bitcast_op.empty())
 		load_expr = join(bitcast_op, "(", load_expr, ")");
 
+	return load_expr;
+}
+
+void CompilerHLSL::emit_load(const Instruction &instruction)
+{
+	auto ops = stream(instruction);
+
+	auto *chain = maybe_get<SPIRAccessChain>(ops[2]);
+	if (chain)
+	{
+		uint32_t result_type = ops[0];
+		uint32_t id = ops[1];
+		uint32_t ptr = ops[2];
+
+		auto load_expr = read_access_chain(*chain);
+
 		bool forward = should_forward(ptr) && forced_temporaries.find(id) == end(forced_temporaries);
 		auto &e = emit_op(result_type, id, load_expr, forward, true);
 		e.need_transpose = false; // TODO: Forward this somehow.
@@ -1994,8 +2003,20 @@ void CompilerHLSL::emit_access_chain(const Instruction &instruction)
 			base = to_expression(ops[2]);
 
 		auto *basetype = &type;
+
+		// Start traversing type hierarchy at the proper non-pointer types.
+		while (basetype->pointer)
+		{
+			assert(basetype->parent_type);
+			basetype = &get<SPIRType>(basetype->parent_type);
+		}
+
+		// Traverse the type hierarchy down to the actual buffer types.
 		for (uint32_t i = 0; i < to_plain_buffer_length; i++)
-			basetype = &get<SPIRType>(type.parent_type);
+		{
+			assert(basetype->parent_type);
+			basetype = &get<SPIRType>(basetype->parent_type);
+		}
 
 		uint32_t matrix_stride = 0;
 		bool need_transpose = false;

spirv_hlsl.hpp

@@ -90,6 +90,7 @@ private:
 	void emit_sampled_image_op(uint32_t result_type, uint32_t result_id, uint32_t image_id, uint32_t samp_id) override;
 	void emit_access_chain(const Instruction &instruction);
 	void emit_load(const Instruction &instruction);
+	std::string read_access_chain(const SPIRAccessChain &chain);
 	void emit_store(const Instruction &instruction);
 
 	const char *to_storage_qualifiers_glsl(const SPIRVariable &var) override;