From 08f342230e056c118dedd9889c558ebcbbb26603 Mon Sep 17 00:00:00 2001
From: Troels Nielsen <bn.troels@gmail.com>
Date: Thu, 26 Aug 2021 17:44:27 +0200
Subject: [PATCH] codegen: parameter attributes on CFunction closures sticks
 (#41827)

When CFunction closures are created an extra argument is added to the
function signature for holding the closure.

Make sure that the parameter attributes on already existing parameters
are not shifted when adding that parameter.
---
 src/codegen.cpp | 41 ++++++++++++++++++++++++++++++++++++++++-
 test/ccall.jl   | 20 ++++++++++++++++++++
 2 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/src/codegen.cpp b/src/codegen.cpp
index 744d29629b0ca..3292df745d90b 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -5180,9 +5180,48 @@ static Function* gen_cfun_wrapper(
         // add nest parameter (pointer to jl_value_t* data array) after sret arg
         assert(closure_types);
         std::vector<Type*> fargt_sig(sig.fargt_sig);
+
         fargt_sig.insert(fargt_sig.begin() + sig.sret, T_pprjlvalue);
+
+        // Shift LLVM attributes for parameters one to the right, as
+        // we are adding the extra nest parameter after sret arg.
+        std::vector<std::pair<unsigned, AttributeSet>> newAttributes;
+        newAttributes.reserve(attributes.getNumAttrSets() + 1);
+        auto it = attributes.index_begin();
+
+        // Skip past FunctionIndex
+        if (it == AttributeList::AttrIndex::FunctionIndex) {
+            ++it;
+        }
+
+        // Move past ReturnValue and parameter return value
+        for (;it < AttributeList::AttrIndex::FirstArgIndex + sig.sret; ++it) {
+            if (attributes.hasAttributes(it)) {
+                newAttributes.emplace_back(it, attributes.getAttributes(it));
+            }
+        }
+
+        // Add the new nest attribute
+        AttrBuilder attrBuilder;
+        attrBuilder.addAttribute(Attribute::Nest);
+        newAttributes.emplace_back(it, AttributeSet::get(jl_LLVMContext, attrBuilder));
+
+        // Shift forward the rest of the attributes
+        for(;it < attributes.index_end(); ++it) {
+            if (attributes.hasAttributes(it)) {
+                newAttributes.emplace_back(it + 1, attributes.getAttributes(it));
+            }
+        }
+
+        // Remember to add back FunctionIndex
+        if (attributes.hasAttributes(AttributeList::AttrIndex::FunctionIndex)) {
+            newAttributes.emplace_back(AttributeList::AttrIndex::FunctionIndex,
+                                       attributes.getAttributes(AttributeList::AttrIndex::FunctionIndex));
+        }
+
+        // Create the new AttributeList
+        attributes = AttributeList::get(jl_LLVMContext, newAttributes);
         functype = FunctionType::get(sig.sret ? T_void : sig.prt, fargt_sig, /*isVa*/false);
-        attributes = attributes.addAttribute(jl_LLVMContext, 1 + sig.sret, Attribute::Nest);
     }
     else {
         functype = sig.functype();
diff --git a/test/ccall.jl b/test/ccall.jl
index 02d005108459e..01f0f4f651aa8 100644
--- a/test/ccall.jl
+++ b/test/ccall.jl
@@ -982,6 +982,26 @@ for (t, v) in ((Complex{Int32}, :ci32), (Complex{Int64}, :ci64),
     end
 end
 
+
+#issue 40164
+@testset "llvm parameter attributes on cfunction closures" begin
+    struct Struct40164
+        x::Cdouble
+        y::Cdouble
+        z::Cdouble
+    end
+
+    function test_40164()
+        ret = Struct40164[]
+        f = x::Struct40164 -> (push!(ret, x); nothing)
+        f_c = @cfunction($f, Cvoid, (Struct40164,))
+        ccall(f_c.ptr, Ptr{Cvoid}, (Struct40164,), Struct40164(0, 1, 2))
+        ret
+    end
+
+    @test test_40164() == [Struct40164(0, 1, 2)]
+end
+
 else
 
 @test_broken "cfunction: no support for closures on this platform"