Support code emission of PTX and GCN even if disabled (#660)

Co-authored-by: Valentin Churavy <[email protected]>

Author: wsmoses

src/gcn.jl

@@ -13,6 +13,9 @@ GCNCompilerTarget(dev_isa; features="") = GCNCompilerTarget(dev_isa, features)
 llvm_triple(::GCNCompilerTarget) = "amdgcn-amd-amdhsa"
 
 function llvm_machine(target::GCNCompilerTarget)
+    @static if :AMDGPU ∉ LLVM.backends()
+        return nothing
+    end
     triple = llvm_triple(target)
     t = Target(triple=triple)
 

src/interface.jl

@@ -23,6 +23,7 @@ source_code(@nospecialize(target::AbstractCompilerTarget)) = "text"
 
 llvm_triple(@nospecialize(target::AbstractCompilerTarget)) = error("Not implemented")
 
+# may return nothing if the target is not support by the current version of LLVM.
 function llvm_machine(@nospecialize(target::AbstractCompilerTarget))
     triple = llvm_triple(target)
 

src/ptx.jl

@@ -45,6 +45,9 @@ source_code(target::PTXCompilerTarget) = "ptx"
 llvm_triple(target::PTXCompilerTarget) = Int===Int64 ? "nvptx64-nvidia-cuda" : "nvptx-nvidia-cuda"
 
 function llvm_machine(target::PTXCompilerTarget)
+    @static if :NVPTX ∉ LLVM.backends()
+        return nothing
+    end
     triple = llvm_triple(target)
     t = Target(triple=triple)
 

test/gcn.jl

@@ -1,3 +1,4 @@
+if :AMDGPU in LLVM.backends()
 @testset "IR" begin
 
 @testset "kernel calling convention" begin
@@ -14,7 +15,6 @@ end
 end
 
 ############################################################################################
-
 @testset "assembly" begin
 
 @testset "skip scalar trap" begin
@@ -214,3 +214,4 @@ end
 end
 
 end
+end # :AMDGPU in LLVM.backends()

test/ptx.jl

@@ -124,7 +124,7 @@ end
 end
 
 ############################################################################################
-
+if :NVPTX in LLVM.backends()
 @testset "assembly" begin
 
 @testset "child functions" begin
@@ -343,3 +343,4 @@ end
 end
 
 end
+end # NVPTX in LLVM.backends()

test/runtests.jl

@@ -116,10 +116,6 @@ end
         push!(skip_tests, "metal")
     end
 end
-if Sys.isapple()
-    # support for AMDGPU and NVTX on macOS has been removed from Julia's LLVM build
-    append!(skip_tests, ["ptx", "gcn"])
-end
 if !(SPIRV_LLVM_Translator_unified_jll.is_available() && SPIRV_Tools_jll.is_available())
     # SPIRV needs it's tools to be available
     push!(skip_tests, "spirv")