From eb58f67727112bc602f98afa568fefe8d1353f66 Mon Sep 17 00:00:00 2001
From: Hans-Kristian Arntzen <hans-kristian.arntzen@arm.com>
Date: Thu, 5 Oct 2017 16:31:52 +0200
Subject: [PATCH] Only unroll matrices for vertex input.

Bandaid, might have to revisit this later.
---
 reference/shaders-hlsl/frag/matrix-input.frag | 26 +++++++++++++++++++
 .../shaders-hlsl/vert/matrix-output.vert      | 23 ++++++++++++++++
 shaders-hlsl/frag/matrix-input.frag           |  9 +++++++
 shaders-hlsl/vert/matrix-output.vert          |  9 +++++++
 spirv_hlsl.cpp                                |  8 ++++--
 5 files changed, 73 insertions(+), 2 deletions(-)
 create mode 100644 reference/shaders-hlsl/frag/matrix-input.frag
 create mode 100644 reference/shaders-hlsl/vert/matrix-output.vert
 create mode 100644 shaders-hlsl/frag/matrix-input.frag
 create mode 100644 shaders-hlsl/vert/matrix-output.vert

diff --git a/reference/shaders-hlsl/frag/matrix-input.frag b/reference/shaders-hlsl/frag/matrix-input.frag
new file mode 100644
index 00000000..92d87d39
--- /dev/null
+++ b/reference/shaders-hlsl/frag/matrix-input.frag
@@ -0,0 +1,26 @@
+static float4 FragColor;
+static float4x4 m;
+
+struct SPIRV_Cross_Input
+{
+    float4x4 m : TEXCOORD1;
+};
+
+struct SPIRV_Cross_Output
+{
+    float4 FragColor : SV_Target0;
+};
+
+void frag_main()
+{
+    FragColor = ((m[0] + m[1]) + m[2]) + m[3];
+}
+
+SPIRV_Cross_Output main(SPIRV_Cross_Input stage_input)
+{
+    m = stage_input.m;
+    frag_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.FragColor = FragColor;
+    return stage_output;
+}
diff --git a/reference/shaders-hlsl/vert/matrix-output.vert b/reference/shaders-hlsl/vert/matrix-output.vert
new file mode 100644
index 00000000..f1290070
--- /dev/null
+++ b/reference/shaders-hlsl/vert/matrix-output.vert
@@ -0,0 +1,23 @@
+static float4 gl_Position;
+static float4x4 m;
+
+struct SPIRV_Cross_Output
+{
+    float4x4 m : TEXCOORD0;
+    float4 gl_Position : SV_Position;
+};
+
+void vert_main()
+{
+    gl_Position = float4(1.0f, 1.0f, 1.0f, 1.0f);
+    m = float4x4(float4(1.0f, 0.0f, 0.0f, 0.0f), float4(0.0f, 1.0f, 0.0f, 0.0f), float4(0.0f, 0.0f, 1.0f, 0.0f), float4(0.0f, 0.0f, 0.0f, 1.0f));
+}
+
+SPIRV_Cross_Output main()
+{
+    vert_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.gl_Position = gl_Position;
+    stage_output.m = m;
+    return stage_output;
+}
diff --git a/shaders-hlsl/frag/matrix-input.frag b/shaders-hlsl/frag/matrix-input.frag
new file mode 100644
index 00000000..ffe242ce
--- /dev/null
+++ b/shaders-hlsl/frag/matrix-input.frag
@@ -0,0 +1,9 @@
+#version 450
+
+layout(location = 0) out vec4 FragColor;
+layout(location = 1) in mat4 m;
+
+void main()
+{
+	FragColor = m[0] + m[1] + m[2] + m[3];
+}
diff --git a/shaders-hlsl/vert/matrix-output.vert b/shaders-hlsl/vert/matrix-output.vert
new file mode 100644
index 00000000..1151d4bd
--- /dev/null
+++ b/shaders-hlsl/vert/matrix-output.vert
@@ -0,0 +1,9 @@
+#version 450
+
+layout(location = 0) out mat4 m;
+
+void main()
+{
+	gl_Position = vec4(1.0);
+	m = mat4(1.0);
+}
diff --git a/spirv_hlsl.cpp b/spirv_hlsl.cpp
index 8f2d902f..bc00235d 100644
--- a/spirv_hlsl.cpp
+++ b/spirv_hlsl.cpp
@@ -518,6 +518,8 @@ void CompilerHLSL::emit_interface_block_in_struct(const SPIRVariable &var, unord
 		SPIRV_CROSS_THROW("All locations from 0 to 63 are exhausted.");
 	};
 
+	bool need_matrix_unroll = var.storage == StorageClassInput && execution.model == ExecutionModelVertex;
+
 	auto &m = meta[var.self].decoration;
 	auto name = to_name(var.self);
 	if (use_binding_number)
@@ -531,7 +533,7 @@ void CompilerHLSL::emit_interface_block_in_struct(const SPIRVariable &var, unord
 		else
 			binding_number = get_vacant_location();
 
-		if (type.columns > 1)
+		if (need_matrix_unroll && type.columns > 1)
 		{
 			if (!type.array.empty())
 				SPIRV_CROSS_THROW("Arrays of matrices used as input/output. This is not supported.");
@@ -1277,12 +1279,14 @@ void CompilerHLSL::emit_hlsl_entry_point()
 			if (var.storage != StorageClassInput)
 				continue;
 
+			bool need_matrix_unroll = var.storage == StorageClassInput && execution.model == ExecutionModelVertex;
+
 			if (!block && !var.remapped_variable && type.pointer && !is_builtin_variable(var) &&
 			    interface_variable_exists_in_entry_point(var.self))
 			{
 				auto name = to_name(var.self);
 				auto &mtype = get<SPIRType>(var.basetype);
-				if (mtype.columns > 1)
+				if (need_matrix_unroll && mtype.columns > 1)
 				{
 					// Unroll matrices.
 					for (uint32_t col = 0; col < mtype.columns; col++)