GCN: Rewrite allocas from AS 0 to 5

src/driver.jl

@@ -138,15 +138,9 @@ function codegen(output::Symbol, job::CompilerJob;
                 fn = LLVM.name(f)
                 LLVM.name!(f, "")
                 f′ = LLVM.Function(ir, fn, eltype(llvmtype(f)))
-                for attr in collect(function_attributes(f))
-                    push!(function_attributes(f′), attr)
-                end
-                for attr in collect(return_attributes(f))
-                    push!(return_attributes(f′), attr)
-                end
-                for i in 1:length(parameters(f)), attr in collect(parameter_attributes(f, i))
-                    push!(parameter_attributes(f′, i), attr)
-                end
+                # copying attributes is broken due to maleadt/LLVM.jl#186,
+                # but that doesn't matter because `only_entry` is only used for reflection,
+                # and the emitted code has already been optimized at this point.
                 replace_uses!(f, f′)
             end
         end

src/gcn.jl

@@ -43,6 +43,7 @@ end
 
 function add_lowering_passes!(job::CompilerJob{GCNCompilerTarget}, pm::LLVM.PassManager)
     add!(pm, ModulePass("LowerThrowExtra", lower_throw_extra!))
+    add!(pm, FunctionPass("FixAllocaAddrspace", fix_alloca_addrspace!))
 end
 
 function lower_throw_extra!(mod::LLVM.Module)
@@ -103,6 +104,33 @@ function lower_throw_extra!(mod::LLVM.Module)
     end
     return changed
 end
+function fix_alloca_addrspace!(fn::LLVM.Function)
+    changed = false
+    alloca_as = 5
+    ctx = context(fn)
+
+    for bb in blocks(fn)
+        for insn in instructions(bb)
+            if isa(insn, LLVM.AllocaInst)
+                ty = llvmtype(insn)
+                ety = eltype(ty)
+                addrspace(ty) == alloca_as && continue
+
+                new_insn = nothing
+                Builder(ctx) do builder
+                    position!(builder, insn)
+                    _alloca = alloca!(builder, ety, name(insn))
+                    new_insn = addrspacecast!(builder, _alloca, ty)
+                end
+                replace_uses!(insn, new_insn)
+                unsafe_delete!(LLVM.parent(insn), insn)
+            end
+        end
+    end
+
+    return changed
+end
+
 
 function emit_trap!(job::CompilerJob{GCNCompilerTarget}, builder, mod, inst)
     ctx = context(mod)

test/gcn.jl

@@ -17,6 +17,17 @@ include("definitions/gcn.jl")
     @test occursin("amdgpu_kernel", ir)
 end
 
+@testset "alloca addrspace" begin
+    function kernel(i)
+        sink(i) # sink provides an alloca in addrspace 0
+        return
+    end
+
+    ir = sprint(io->gcn_code_llvm(io, kernel, Tuple{Int64}; dump_module=true))
+    @test occursin("alloca i64, addrspace(5)", ir)
+    @test !occursin("alloca i64\n", ir)
+end
+
 end
 
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