Auto merge of #54993 - TimNN:pda-tdl, r=eddyb

Support for the program data address space option of LLVM's Target Datalayout

This was introduced recently (specifically, for AVR, cc @dylanmckay).

(I came up with this when attempting to run [avr-rust](https://github.com/avr-rust/rust) rebased on the latest [rust-lang](https://github.com/rust-lang/rust) commits. If this requires a different design, some additional discussions, or is not something to pursue right now, I'd be happy to close this PR).

Note that this somewhat overlaps with @DiamondLovesYou's #51576, I think, although the implementation here is significantly simpler: Since the address space applies to _all_ program data, we can just check the pointee's type whenever we create an LLVM pointer type. If it is a function we use the program data address space; if not we use the default address space.

cc @eddyb, who has been reviewing #51576

Ref: https://llvm.org/docs/LangRef.html#data-layout

4 files changed, 13 insertions, 3 deletions

diff --git a/src/librustc_codegen_llvm/abi.rs b/src/librustc_codegen_llvm/abi.rs
index bd7a1c2c329..03b0b04d401 100644
--- a/src/librustc_codegen_llvm/abi.rs
+++ b/src/librustc_codegen_llvm/abi.rs
@@ -19,7 +19,7 @@ use type_::Type;
 use type_of::{LayoutLlvmExt, PointerKind};
 use value::Value;
 
-use rustc_target::abi::{LayoutOf, Size, TyLayout, Abi as LayoutAbi};
+use rustc_target::abi::{HasDataLayout, LayoutOf, Size, TyLayout, Abi as LayoutAbi};
 use rustc::ty::{self, Ty};
 use rustc::ty::layout;
 
@@ -277,6 +277,7 @@ pub trait FnTypeExt<'tcx> {
                       cx: &CodegenCx<'ll, 'tcx>,
                       abi: Abi);
     fn llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type;
+    fn ptr_to_llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type;
     fn llvm_cconv(&self) -> llvm::CallConv;
     fn apply_attrs_llfn(&self, llfn: &'ll Value);
     fn apply_attrs_callsite(&self, bx: &Builder<'a, 'll, 'tcx>, callsite: &'ll Value);
@@ -658,6 +659,13 @@ impl<'tcx> FnTypeExt<'tcx> for FnType<'tcx, Ty<'tcx>> {
         }
     }
 
+    fn ptr_to_llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type {
+        unsafe {
+            llvm::LLVMPointerType(self.llvm_type(cx),
+                                  cx.data_layout().instruction_address_space as c_uint)
+        }
+    }
+
     fn llvm_cconv(&self) -> llvm::CallConv {
         match self.conv {
             Conv::C => llvm::CCallConv,
diff --git a/src/librustc_codegen_llvm/meth.rs b/src/librustc_codegen_llvm/meth.rs
index d38f343d01f..0dc5a4ddde8 100644
--- a/src/librustc_codegen_llvm/meth.rs
+++ b/src/librustc_codegen_llvm/meth.rs
@@ -39,7 +39,7 @@ impl<'a, 'tcx> VirtualIndex {
         // Load the data pointer from the object.
         debug!("get_fn({:?}, {:?})", llvtable, self);
 
-        let llvtable = bx.pointercast(llvtable, fn_ty.llvm_type(bx.cx).ptr_to().ptr_to());
+        let llvtable = bx.pointercast(llvtable, fn_ty.ptr_to_llvm_type(bx.cx).ptr_to());
         let ptr_align = bx.tcx().data_layout.pointer_align;
         let ptr = bx.load(bx.inbounds_gep(llvtable, &[C_usize(bx.cx, self.0)]), ptr_align);
         bx.nonnull_metadata(ptr);
diff --git a/src/librustc_codegen_llvm/type_.rs b/src/librustc_codegen_llvm/type_.rs
index 51a233d7916..6fb78fe4aa5 100644
--- a/src/librustc_codegen_llvm/type_.rs
+++ b/src/librustc_codegen_llvm/type_.rs
@@ -234,6 +234,8 @@ impl Type {
     }
 
     pub fn ptr_to(&self) -> &Type {
+        assert_ne!(self.kind(), TypeKind::Function,
+                   "don't call ptr_to on function types, use ptr_to_llvm_type on FnType instead");
         unsafe {
             llvm::LLVMPointerType(self, 0)
         }
diff --git a/src/librustc_codegen_llvm/type_of.rs b/src/librustc_codegen_llvm/type_of.rs
index b01d7e3a776..fea02edf7be 100644
--- a/src/librustc_codegen_llvm/type_of.rs
+++ b/src/librustc_codegen_llvm/type_of.rs
@@ -265,7 +265,7 @@ impl<'tcx> LayoutLlvmExt<'tcx> for TyLayout<'tcx> {
                         ty::ParamEnv::reveal_all(),
                         &sig,
                     );
-                    FnType::new(cx, sig, &[]).llvm_type(cx).ptr_to()
+                    FnType::new(cx, sig, &[]).ptr_to_llvm_type(cx)
                 }
                 _ => self.scalar_llvm_type_at(cx, scalar, Size::ZERO)
             };