From a3ff3965e16aeaa9fb3bdf43254802c0a86cbc9a Mon Sep 17 00:00:00 2001
From: Dylan McKay <me@dylanmckay.io>
Date: Tue, 23 Jun 2020 18:23:00 +1200
Subject: [PATCH] Fix a bug in the pointer address space assignment code

The code was not checking the "function-ness" of the type at the correct
level. It was checking the "root type", which may be, say a struct, but
would use that exclusively for classifying the address spaces of the
fields within the struct. A function pointer within a struct would
be incorrectly defined with address space 0 only because its parent struct
is in address space 0.

This patch also moves the address space classification logic for
constants down a layer, which allows removal of the address space
parameter from a few functions, and fixes the problem at the source
rather than patching over top of it in a method higher up in the call
stack.
---
 src/librustc_codegen_llvm/common.rs |  5 ++---
 src/librustc_codegen_llvm/consts.rs | 23 ++++++++++-------------
 2 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/src/librustc_codegen_llvm/common.rs b/src/librustc_codegen_llvm/common.rs
index 3e82a2db5c772..3c00f14bccb76 100644
--- a/src/librustc_codegen_llvm/common.rs
+++ b/src/librustc_codegen_llvm/common.rs
@@ -246,8 +246,7 @@ impl ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
             Scalar::Ptr(ptr) => {
                 let base_addr = match self.tcx.global_alloc(ptr.alloc_id) {
                     GlobalAlloc::Memory(alloc) => {
-                        let init =
-                            const_alloc_to_llvm(self, alloc, self.address_space_of_type(llty));
+                        let init = const_alloc_to_llvm(self, alloc);
                         let value = match alloc.mutability {
                             Mutability::Mut => self.static_addr_of_mut(init, alloc.align, None),
                             _ => self.static_addr_of(init, alloc.align, None),
@@ -297,7 +296,7 @@ impl ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
             let llval = self.const_usize(alloc.align.bytes());
             unsafe { llvm::LLVMConstIntToPtr(llval, llty) }
         } else {
-            let init = const_alloc_to_llvm(self, alloc, address_space);
+            let init = const_alloc_to_llvm(self, alloc);
             let base_addr = self.static_addr_of(init, alloc.align, None);
 
             let llval = unsafe {
diff --git a/src/librustc_codegen_llvm/consts.rs b/src/librustc_codegen_llvm/consts.rs
index 3379fce3beb96..0aa0cf33d1c39 100644
--- a/src/librustc_codegen_llvm/consts.rs
+++ b/src/librustc_codegen_llvm/consts.rs
@@ -13,7 +13,7 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::Node;
 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
 use rustc_middle::mir::interpret::{
-    read_target_uint, Allocation, ConstValue, ErrorHandled, Pointer,
+    read_target_uint, Allocation, ConstValue, ErrorHandled, GlobalAlloc, Pointer,
 };
 use rustc_middle::mir::mono::MonoItem;
 use rustc_middle::ty::{self, Instance, Ty};
@@ -24,11 +24,7 @@ use rustc_target::abi::{AddressSpace, Align, HasDataLayout, LayoutOf, Primitive,
 
 use std::ffi::CStr;
 
-pub fn const_alloc_to_llvm(
-    cx: &CodegenCx<'ll, '_>,
-    alloc: &Allocation,
-    address_space: AddressSpace,
-) -> &'ll Value {
+pub fn const_alloc_to_llvm(cx: &CodegenCx<'ll, '_>, alloc: &Allocation) -> &'ll Value {
     let mut llvals = Vec::with_capacity(alloc.relocations().len() + 1);
     let dl = cx.data_layout();
     let pointer_size = dl.pointer_size.bytes() as usize;
@@ -57,6 +53,12 @@ pub fn const_alloc_to_llvm(
         )
         .expect("const_alloc_to_llvm: could not read relocation pointer")
             as u64;
+
+        let address_space = match cx.tcx.global_alloc(alloc_id) {
+            GlobalAlloc::Function(..) => cx.data_layout().instruction_address_space,
+            GlobalAlloc::Static(..) | GlobalAlloc::Memory(..) => AddressSpace::DATA,
+        };
+
         llvals.push(cx.scalar_to_backend(
             Pointer::new(alloc_id, Size::from_bytes(ptr_offset)).into(),
             &Scalar { value: Primitive::Pointer, valid_range: 0..=!0 },
@@ -83,17 +85,12 @@ pub fn codegen_static_initializer(
     cx: &CodegenCx<'ll, 'tcx>,
     def_id: DefId,
 ) -> Result<(&'ll Value, &'tcx Allocation), ErrorHandled> {
-    let address_space = if cx.tcx.type_of(def_id).is_fn() {
-        cx.data_layout().instruction_address_space
-    } else {
-        AddressSpace::DATA
-    };
-
     let alloc = match cx.tcx.const_eval_poly(def_id)? {
         ConstValue::ByRef { alloc, offset } if offset.bytes() == 0 => alloc,
         val => bug!("static const eval returned {:#?}", val),
     };
-    Ok((const_alloc_to_llvm(cx, alloc, address_space), alloc))
+
+    Ok((const_alloc_to_llvm(cx, alloc), alloc))
 }
 
 fn set_global_alignment(cx: &CodegenCx<'ll, '_>, gv: &'ll Value, mut align: Align) {