Do not forward expressions which carry a huge amount of dependencies.

Need to force temporaries eventually, or compilers have a tendency to
explode.

1 files changed, 8 insertions, 0 deletions

diff --git a/spirv_glsl.cpp b/spirv_glsl.cpp
index a96c9671..e43398a1 100644
--- a/spirv_glsl.cpp
+++ b/spirv_glsl.cpp
@@ -9498,6 +9498,7 @@ bool CompilerGLSL::should_forward(uint32_t id) const
 {
 	// If id is a variable we will try to forward it regardless of force_temporary check below
 	// This is important because otherwise we'll get local sampler copies (highp sampler2D foo = bar) that are invalid in OpenGL GLSL
+
 	auto *var = maybe_get<SPIRVariable>(id);
 	if (var && var->forwardable)
 		return true;
@@ -9506,6 +9507,13 @@ bool CompilerGLSL::should_forward(uint32_t id) const
 	if (options.force_temporary)
 		return false;
 
+	// If an expression carries enough dependencies we need to stop forwarding at some point,
+	// or we explode compilers. There are usually limits to how much we can nest expressions.
+	auto *expr = maybe_get<SPIRExpression>(id);
+	const uint32_t max_expression_dependencies = 64;
+	if (expr && expr->expression_dependencies.size() >= max_expression_dependencies)
+		return false;
+
 	// Immutable expression can always be forwarded.
 	if (is_immutable(id))
 		return true;