add pass to replace copysign.f16

src/spirv.jl

@@ -27,6 +27,7 @@ Base.@kwdef struct SPIRVCompilerTarget <: AbstractCompilerTarget
     extensions::Vector{String} = []
     supports_fp16::Bool = true
     supports_fp64::Bool = true
+    replace_copysign_f16 = false
 
     backend::Symbol = isavailable(SPIRV_LLVM_Backend_jll) ? :llvm : :khronos
     # XXX: these don't really belong in the _target_ struct
@@ -118,6 +119,9 @@ end
     # (SPIRV-LLVM-Translator#1140)
     rm_freeze!(mod)
 
+    # replace copysign.f16 intrinsic with manual implementation since pocl doesn't support it
+    job.config.target.replace_copysign_f16 && replace_copysign_f16!(mod)
+
     # translate to SPIR-V
     input = tempname(cleanup=false) * ".bc"
     translated = tempname(cleanup=false) * ".spv"
@@ -350,3 +354,63 @@ function wrap_byval(@nospecialize(job::CompilerJob), mod::LLVM.Module, f::LLVM.F
 
     return new_f
 end
+
+# replace llvm.copysign.f16 calls with manual implementation
+function replace_copysign_f16!(mod::LLVM.Module)
+    job = current_job::CompilerJob
+    changed = false
+    @tracepoint "replace copysign f16" begin
+
+    # Find llvm.copysign.f16 intrinsic
+    copysign_name = "llvm.copysign.f16"
+    if haskey(functions(mod), copysign_name)
+        copysign_fn = functions(mod)[copysign_name]
+
+        # Process all uses of the intrinsic
+        for use in uses(copysign_fn)
+            call_inst = user(use)
+            if isa(call_inst, LLVM.CallInst)
+                @dispose builder=IRBuilder() begin
+                    # Position builder before the call
+                    position!(builder, call_inst)
+
+                    # Get operands (x and y)
+                    x = operands(call_inst)[1]  # magnitude
+                    y = operands(call_inst)[2]  # sign source
+
+                    # Create the replacement implementation
+                    i16_type = LLVM.IntType(16)
+
+                    # Bitcast half values to i16
+                    x_bits = bitcast!(builder, x, i16_type)
+                    y_bits = bitcast!(builder, y, i16_type)
+
+                    # XOR the bit patterns and check if result is negative
+                    xor_result = xor!(builder, y_bits, x_bits)
+                    is_negative = icmp!(builder, LLVM.API.LLVMIntSLT, xor_result,
+                                      ConstantInt(i16_type, 0))
+
+                    # Create fneg of x
+                    neg_x = fneg!(builder, x)
+
+                    # Select between neg_x and x based on the sign test
+                    result = select!(builder, is_negative, neg_x, x)
+
+                    # Replace uses and erase the original call
+                    replace_uses!(call_inst, result)
+                    erase!(call_inst)
+                    changed = true
+                end
+            end
+        end
+
+        # Remove the intrinsic declaration if no longer used
+        if isempty(uses(copysign_fn))
+            erase!(copysign_fn)
+        end
+    end
+
+    end
+    return changed
+end
+