Add support for custom IR validation passes.

Author: maleadt

src/interface.jl

@@ -243,6 +243,9 @@ end
 # post-Julia optimization processing of the module
 optimize_module!(@nospecialize(job::CompilerJob), mod::LLVM.Module) = return
 
+# whether an LLVM function is valid for this back-end
+validate_module(@nospecialize(job::CompilerJob), mod::LLVM.Module) = IRError[]
+
 # finalization of the module, before deferred codegen and optimization
 function finish_module!(@nospecialize(job::CompilerJob), mod::LLVM.Module, entry::LLVM.Function)
     return entry

src/metal.jl

@@ -63,6 +63,21 @@ function process_entry!(job::CompilerJob{MetalCompilerTarget}, mod::LLVM.Module,
     return entry
 end
 
+function validate_module(job::CompilerJob{MetalCompilerTarget}, mod::LLVM.Module)
+    errors = IRError[]
+
+    T_double = LLVM.DoubleType(context(mod))
+
+    for fun in functions(mod), bb in blocks(fun), inst in instructions(bb)
+        if llvmtype(inst) == T_double || any(param->llvmtype(param) == T_double, operands(inst))
+            bt = backtrace(inst)
+            push!(errors, ("use of double floating-point value", bt, inst))
+        end
+    end
+
+    return errors
+end
+
 # TODO: why is this done in finish_module? maybe just in process_entry?
 function finish_module!(@nospecialize(job::CompilerJob{MetalCompilerTarget}), mod::LLVM.Module, entry::LLVM.Function)
     entry = invoke(finish_module!, Tuple{CompilerJob, LLVM.Module, LLVM.Function}, job, mod, entry)

src/validation.jl

@@ -147,6 +147,9 @@ function check_ir!(job, errors::Vector{IRError}, mod::LLVM.Module)
         check_ir!(job, errors, f)
     end
 
+    # custom validation
+    append!(errors, validate_module(job, mod))
+
     return errors
 end