From 5fce502cc31fa6e2da6d0b5e86dc79f03a816b5c Mon Sep 17 00:00:00 2001
From: William Moses <gh@wsmoses.com>
Date: Fri, 3 Feb 2023 13:46:44 -0500
Subject: [PATCH] Add nthfield (#594)

---
 src/compiler.jl | 65 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 64 insertions(+), 1 deletion(-)

diff --git a/src/compiler.jl b/src/compiler.jl
index 128eb9d075..e46c1c23a4 100644
--- a/src/compiler.jl
+++ b/src/compiler.jl
@@ -1962,6 +1962,63 @@ function jlcall2_rev(B::LLVM.API.LLVMBuilderRef, OrigCI::LLVM.API.LLVMValueRef,
     return nothing
 end
 
+function jl_nthfield_fwd(B::LLVM.API.LLVMBuilderRef, OrigCI::LLVM.API.LLVMValueRef, gutils::API.EnzymeGradientUtilsRef, normalR::Ptr{LLVM.API.LLVMValueRef}, shadowR::Ptr{LLVM.API.LLVMValueRef})::Cvoid
+    if shadowR != C_NULL
+        orig = LLVM.Instruction(OrigCI)
+        origops = collect(operands(orig))
+        width = API.EnzymeGradientUtilsGetWidth(gutils)
+        if API.EnzymeGradientUtilsIsConstantValue(gutils, origops[1]) == 0
+            B = LLVM.Builder(B)
+
+            shadowin = LLVM.Value(API.EnzymeGradientUtilsInvertPointer(gutils, origops[1], B))
+            if width == 1
+                args = LLVM.Value[
+                                  shadowin
+                                  LLVM.Value(API.EnzymeGradientUtilsNewFromOriginal(gutils, origops[2]))
+                                  ]
+                shadowres = LLVM.call!(B, LLVM.called_value(orig), args)
+                conv = LLVM.API.LLVMGetInstructionCallConv(orig)
+                LLVM.API.LLVMSetInstructionCallConv(shadowres, conv)
+            else
+                shadowres = UndefValue(LLVM.LLVMType(API.EnzymeGetShadowType(width, llvmtype(orig))))
+                for idx in 1:width
+                    args = LLVM.Value[
+                                      extract_value!(B, shadowin, idx-1)
+                                      LLVM.Value(API.EnzymeGradientUtilsNewFromOriginal(gutils, origops[2]))
+                                      ]
+                    tmp = LLVM.call!(B, LLVM.called_value(orig), args)
+                    conv = LLVM.API.LLVMGetInstructionCallConv(orig)
+                    LLVM.API.LLVMSetInstructionCallConv(tmp, conv)
+                    shadowres = insert_value!(B, shadowres, tmp, idx-1)
+                end
+            end
+            unsafe_store!(shadowR, shadowres.ref)
+        else
+            normal = LLVM.Value(API.EnzymeGradientUtilsNewFromOriginal(gutils, orig))
+            if width == 1
+                shadowres = normal
+            else
+                shadowres = UndefValue(LLVM.LLVMType(API.EnzymeGetShadowType(width, llvmtype(normal))))
+                for idx in 1:width
+                    shadowres = insert_value!(B, shadowres, normal, idx-1)
+                end
+            end
+            unsafe_store!(shadowR, shadowres.ref)
+        end
+    end
+    return nothing
+end
+function jl_nthfield_augfwd(B::LLVM.API.LLVMBuilderRef, OrigCI::LLVM.API.LLVMValueRef, gutils::API.EnzymeGradientUtilsRef, normalR::Ptr{LLVM.API.LLVMValueRef}, shadowR::Ptr{LLVM.API.LLVMValueRef}, tapeR::Ptr{LLVM.API.LLVMValueRef})::Cvoid
+  jl_nthfield_fwd(B, OrigCI, gutils, normalR, shadowR)
+end
+function jl_nthfield_rev(B::LLVM.API.LLVMBuilderRef, OrigCI::LLVM.API.LLVMValueRef, gutils::API.EnzymeGradientUtilsRef, tape::LLVM.API.LLVMValueRef)::Cvoid 
+    orig = LLVM.Instruction(OrigCI)
+    if API.EnzymeGradientUtilsIsConstantValue(gutils, orig) == 0
+        emit_error(LLVM.Builder(B), orig, "Enzyme: not yet implemented in reverse mode, jl_nthfield")
+    end
+    return nothing
+end
+
 function common_invoke_fwd(offset, B::LLVM.API.LLVMBuilderRef, OrigCI::LLVM.API.LLVMValueRef, gutils::API.EnzymeGradientUtilsRef, normalR::Ptr{LLVM.API.LLVMValueRef}, shadowR::Ptr{LLVM.API.LLVMValueRef})::Cvoid
     orig = LLVM.Instruction(OrigCI)
 
@@ -4606,6 +4663,12 @@ function __init__()
         @cfunction(jl_getfield_rev, Cvoid, (LLVM.API.LLVMBuilderRef, LLVM.API.LLVMValueRef, API.EnzymeGradientUtilsRef, LLVM.API.LLVMValueRef)),
         @cfunction(jl_getfield_fwd, Cvoid, (LLVM.API.LLVMBuilderRef, LLVM.API.LLVMValueRef, API.EnzymeGradientUtilsRef, Ptr{LLVM.API.LLVMValueRef}, Ptr{LLVM.API.LLVMValueRef})),
     )
+    register_handler!(
+        ("ijl_get_nth_field_checked","jl_get_nth_field_checked"),
+        @cfunction(jl_nthfield_augfwd, Cvoid, (LLVM.API.LLVMBuilderRef, LLVM.API.LLVMValueRef, API.EnzymeGradientUtilsRef, Ptr{LLVM.API.LLVMValueRef}, Ptr{LLVM.API.LLVMValueRef}, Ptr{LLVM.API.LLVMValueRef})),
+        @cfunction(jl_nthfield_rev, Cvoid, (LLVM.API.LLVMBuilderRef, LLVM.API.LLVMValueRef, API.EnzymeGradientUtilsRef, LLVM.API.LLVMValueRef)),
+        @cfunction(jl_nthfield_fwd, Cvoid, (LLVM.API.LLVMBuilderRef, LLVM.API.LLVMValueRef, API.EnzymeGradientUtilsRef, Ptr{LLVM.API.LLVMValueRef}, Ptr{LLVM.API.LLVMValueRef})),
+    )
     register_handler!(
         ("jl_array_sizehint","ijl_array_sizehint"),
         @cfunction(jl_array_sizehint_augfwd, Cvoid, (LLVM.API.LLVMBuilderRef, LLVM.API.LLVMValueRef, API.EnzymeGradientUtilsRef, Ptr{LLVM.API.LLVMValueRef}, Ptr{LLVM.API.LLVMValueRef}, Ptr{LLVM.API.LLVMValueRef})),
@@ -4768,7 +4831,7 @@ function annotate!(mod, mode)
         end
     end
 
-    for fname in ("jl_f_getfield",)
+    for fname in ("jl_f_getfield","ijl_f_getfield","jl_get_nth_field_checked","ijl_get_nth_field_checked")
         if haskey(fns, fname)
             fn = fns[fname]
             push!(function_attributes(fn), LLVM.EnumAttribute("readonly", 0; ctx))