Add tests for muladd override and LLVM intrinsic fma/muladd codegen

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: vchuravy

test/core/codegen.jl

@@ -22,6 +22,31 @@ end
     @test !occursin("@__nv_fmaf", ir)
 end
 
+@testset "fma uses LLVM intrinsic" begin
+    function fma_kernel(ptr)
+        unsafe_store!(ptr, fma(unsafe_load(ptr), unsafe_load(ptr,2), unsafe_load(ptr,3)))
+        return
+    end
+
+    for (T, suffix) in ((Float32, "f32"), (Float64, "f64"), (Float16, "f16"))
+        ir = sprint(io->CUDA.code_llvm(io, fma_kernel, Tuple{Ptr{T}}))
+        @test occursin("llvm.fma.$suffix", ir)
+        @test !occursin("__nv_fma", ir)
+    end
+end
+
+@testset "muladd uses LLVM intrinsic" begin
+    function muladd_kernel(ptr)
+        unsafe_store!(ptr, muladd(unsafe_load(ptr), unsafe_load(ptr,2), unsafe_load(ptr,3)))
+        return
+    end
+
+    for (T, suffix) in ((Float32, "f32"), (Float64, "f64"), (Float16, "f16"))
+        ir = sprint(io->CUDA.code_llvm(io, muladd_kernel, Tuple{Ptr{T}}))
+        @test occursin("llvm.fmuladd.$suffix", ir)
+    end
+end
+
 @testset "assume" begin
     foo(i) = cld(42, i)
     ir = sprint(io->CUDA.code_llvm(io, foo, Tuple{Int}))

test/core/device/intrinsics/math.jl

@@ -85,6 +85,35 @@ using SpecialFunctions
         end
     end
 
+    @testset "muladd" begin
+        for T in (Float16, Float32, Float64)
+            @test testf((x,y,z)->muladd.(x,y,z), rand(T, 1), rand(T, 1), rand(T, 1))
+            @test testf((x,y,z)->muladd.(x,y,z), rand(T, 1), -rand(T, 1), -rand(T, 1))
+        end
+    end
+
+    @testset "fma/muladd PTX codegen" begin
+        # fma and muladd should both lower to fma.rn in PTX
+        function fma_kernel(a, b, c)
+            @inbounds a[] = fma(b[], c[], a[])
+            return
+        end
+        function muladd_kernel(a, b, c)
+            @inbounds a[] = muladd(b[], c[], a[])
+            return
+        end
+
+        for T in (Float32, Float64)
+            asm = sprint(io->CUDA.code_ptx(io, fma_kernel,
+                NTuple{3,CuDeviceArray{T,1,AS.Global}}))
+            @test occursin("fma.rn", asm)
+
+            asm = sprint(io->CUDA.code_ptx(io, muladd_kernel,
+                NTuple{3,CuDeviceArray{T,1,AS.Global}}))
+            @test occursin("fma.rn", asm)
+        end
+    end
+
     # something from SpecialFunctions.jl
     @testset "erf" begin
         @test testf(a->SpecialFunctions.erf.(a), Float32[1.0])