Merge duplicate functions from deferred codegen. (#242)

Author: maleadt

Manifest.toml

@@ -39,9 +39,9 @@ version = "1.3.0"
 
 [[LLVM]]
 deps = ["CEnum", "LLVMExtra_jll", "Libdl", "Printf", "Unicode"]
-git-tree-sha1 = "23a47d417a3cd9c2e73c854bac7dd4731c105ef7"
+git-tree-sha1 = "29174613a9fa0424f5aef1a9dbd234acff7ce1f2"
 uuid = "929cbde3-209d-540e-8aea-75f648917ca0"
-version = "4.4.0"
+version = "4.5.0"
 
 [[LLVMExtra_jll]]
 deps = ["Artifacts", "JLLWrappers", "Libdl", "Pkg"]

Project.toml

@@ -14,7 +14,7 @@ UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 
 [compat]
 ExprTools = "0.1"
-LLVM = "4.4"
+LLVM = "4.5"
 TimerOutputs = "0.5"
 julia = "1.6"
 

src/driver.jl

@@ -281,18 +281,22 @@ const __llvm_initialized = Ref(false)
             end
         end
 
-        # merge constants (such as exception messages) from each entry
-        # and on platforms that support it inline and optimize the call to
-        # the deferred code, in particular we want to remove unnecessary
-        # alloca's that are created by pass-by-ref semantics.
         ModulePassManager() do pm
+            # inline and optimize the call to the deferred code. in particular we want to
+            # remove unnecessary alloca's that are created by pass-by-ref semantics.
             instruction_combining!(pm)
-            constant_merge!(pm)
             always_inliner!(pm)
             scalar_repl_aggregates_ssa!(pm)
             promote_memory_to_register!(pm)
             gvn!(pm)
 
+            # merge constants (such as exception messages) from each entry
+            constant_merge!(pm)
+
+            # merge duplicate functions, since each compilation invocation emits everything
+            # XXX: ideally we want to avoid emitting these in the first place
+            merge_functions!(pm)
+
             run!(pm, ir)
         end