Clean-up LLVM for SPIR-V before mcgen. (#277)

Author: maleadt

src/spirv.jl

@@ -70,23 +70,26 @@ function finish_module!(job::CompilerJob{SPIRVCompilerTarget}, mod::LLVM.Module,
           MDNode([ConstantInt(Int32(1); ctx),
                   ConstantInt(Int32(5); ctx)]; ctx))
 
+    return entry
+end
+
+@unlocked function mcgen(job::CompilerJob{SPIRVCompilerTarget}, mod::LLVM.Module,
+                         format=LLVM.API.LLVMAssemblyFile)
+    # The SPIRV Tools don't handle Julia's debug info, rejecting DW_LANG_Julia...
+    strip_debuginfo!(mod)
+
     ModulePassManager() do pm
         # SPIR-V does not support trap, and has no mechanism to abort compute kernels
         # (OpKill is only available in fragment execution mode)
         add!(pm, ModulePass("RemoveTrap", rm_trap!))
+
+        # the LLVM to SPIR-V translator does not support the freeze instruction
+        # (SPIRV-LLVM-Translator#1140)
         add!(pm, ModulePass("RemoveFreeze", rm_freeze!))
 
         run!(pm, mod)
     end
 
-    return entry
-end
-
-@unlocked function mcgen(job::CompilerJob{SPIRVCompilerTarget}, mod::LLVM.Module,
-                         format=LLVM.API.LLVMAssemblyFile)
-    # The SPIRV Tools don't handle Julia's debug info, rejecting DW_LANG_Julia...
-    strip_debuginfo!(mod)
-
     # translate to SPIR-V
     input = tempname(cleanup=false) * ".bc"
     translated = tempname(cleanup=false) * ".spv"