Generalize check_ir_values (#630)

Use that to have Metal support Float64 in the context of logging.

Co-authored-by: Tim Besard <tim.besard@gmail.com>

Author: tgymnich

src/metal.jl

@@ -89,8 +89,32 @@ end
 function validate_ir(job::CompilerJob{MetalCompilerTarget}, mod::LLVM.Module)
     errors = IRError[]
 
-    # Metal never supports double precision
-    append!(errors, check_ir_values(mod, LLVM.DoubleType()))
+    # Metal does not support double precision, except for logging
+    function is_illegal_double(val)
+        T_bad = LLVM.DoubleType()
+        if value_type(val) != T_bad
+            return false
+        end
+
+        function used_for_logging(use::LLVM.Use)
+            usr = user(use)
+            if usr isa LLVM.CallInst
+                callee = called_operand(usr)
+                if callee isa LLVM.Function && startswith(name(callee), "metal_os_log")
+                    return true
+                end
+            end
+            return false
+        end
+        if all(used_for_logging, uses(val))
+            return false
+        end
+
+        return true
+    end
+    append!(errors, check_ir_values(mod, is_illegal_double, "use of double value"))
+
+    # Metal never supports 128-bit integers
     append!(errors, check_ir_values(mod, LLVM.IntType(128)))
 
     errors

src/validation.jl

@@ -317,16 +317,18 @@ function check_ir!(job, errors::Vector{IRError}, inst::LLVM.CallInst)
     return errors
 end
 
-# helper function to check if a LLVM module uses values of a certain type
-function check_ir_values(mod::LLVM.Module, T_bad::LLVMType)
+# helper function to check for illegal values in an LLVM module
+function check_ir_values(mod::LLVM.Module, predicate, msg="value")
     errors = IRError[]
-
     for fun in functions(mod), bb in blocks(fun), inst in instructions(bb)
-        if value_type(inst) == T_bad || any(param->value_type(param) == T_bad, operands(inst))
+        if predicate(inst) || any(predicate, operands(inst))
             bt = backtrace(inst)
-            push!(errors, ("use of $(string(T_bad)) value", bt, inst))
+            push!(errors, (msg, bt, inst))
         end
     end
-
     return errors
 end
+## shorthand to check for illegal value types
+function check_ir_values(mod::LLVM.Module, T_bad::LLVMType)
+    check_ir_values(mod, val -> value_type(val) == T_bad, "use of $(string(T_bad)) value")
+end

test/metal_tests.jl

@@ -79,6 +79,53 @@ end
     @test occursin("air.max.s.v2i64", ir)
 end
 
+@testset "unsupported type detection" begin
+    function kernel1(ptr)
+        buf = reinterpret(Ptr{Float32}, ptr)
+        val = unsafe_load(buf)
+        dval = Cdouble(val)
+        # ccall("extern metal_os_log", llvmcall, Nothing, (Float64,), dval)
+        Base.llvmcall(("""
+        declare void @llvm.va_start(i8*)
+        declare void @llvm.va_end(i8*)
+        declare void @air.os_log(i8*, i64)
+        
+        define void @metal_os_log(...) {
+            %1 = alloca i8*
+            %2 = bitcast i8** %1 to i8*
+            call void @llvm.va_start(i8* %2)
+            %3 = load i8*, i8** %1
+            call void @air.os_log(i8* %3, i64 8)
+            call void @llvm.va_end(i8* %2)
+            ret void
+        }
+
+        define void @entry(double %val) #0 {
+            call void (...) @metal_os_log(double %val)
+            ret void
+        }
+
+        attributes #0 = { alwaysinline }""", "entry"),
+        Nothing, Tuple{Float64}, dval)
+        return
+    end
+
+
+    ir = sprint(io->Metal.code_llvm(io, kernel1, Tuple{Core.LLVMPtr{Float32,1}}; validate=true))
+    @test occursin("@metal_os_log", ir)
+
+    function kernel2(ptr)
+        val = unsafe_load(ptr)
+        res = val * val
+        unsafe_store!(ptr, res)
+        return
+    end
+
+    @test_throws_message(InvalidIRError, Metal.code_llvm(devnull, kernel2, Tuple{Core.LLVMPtr{Float64,1}}; validate=true)) do msg
+        occursin("unsupported use of double value", msg)
+    end
+end
+
 end
 
 end