Auto merge of #69478 - avr-rust:avr-support-upstream, r=jonas-schievink

Enable AVR as a Tier 3 target upstream

Tracking issue: #44052.

Things intentionally left out of the initial upstream:

* The `target_cpu` flag

I have made the cleanup suggestions by @jplatte and @jplatte in avr-rust@043550d.

Anybody feel free to give the branch a test and see how it fares, or make suggestions on the code patch itself.

Author: bors

config.toml.example

@@ -69,7 +69,7 @@
 # the same format as above, but since these targets are experimental, they are
 # not built by default and the experimental Rust compilation targets that depend
 # on them will not work unless the user opts in to building them.
-#experimental-targets = ""
+#experimental-targets = "AVR"
 
 # Cap the number of parallel linker invocations when compiling LLVM.
 # This can be useful when building LLVM with debug info, which significantly

src/bootstrap/native.rs

@@ -144,7 +144,7 @@ impl Step for Llvm {
 
         let llvm_exp_targets = match builder.config.llvm_experimental_targets {
             Some(ref s) => s,
-            None => "",
+            None => "AVR",
         };
 
         let assertions = if builder.config.llvm_assertions { "ON" } else { "OFF" };

src/libcore/ptr/mod.rs

@@ -1345,14 +1345,24 @@ macro_rules! fnptr_impls_safety_abi {
         #[stable(feature = "fnptr_impls", since = "1.4.0")]
         impl<Ret, $($Arg),*> fmt::Pointer for $FnTy {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-                fmt::Pointer::fmt(&(*self as *const ()), f)
+                // HACK: The intermediate cast as usize is required for AVR
+                // so that the address space of the source function pointer
+                // is preserved in the final function pointer.
+                //
+                // https://github.com/avr-rust/rust/issues/143
+                fmt::Pointer::fmt(&(*self as usize as *const ()), f)
             }
         }
 
         #[stable(feature = "fnptr_impls", since = "1.4.0")]
         impl<Ret, $($Arg),*> fmt::Debug for $FnTy {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-                fmt::Pointer::fmt(&(*self as *const ()), f)
+                // HACK: The intermediate cast as usize is required for AVR
+                // so that the address space of the source function pointer
+                // is preserved in the final function pointer.
+                //
+                // https://github.com/avr-rust/rust/issues/143
+                fmt::Pointer::fmt(&(*self as usize as *const ()), f)
             }
         }
     }

src/librustc_ast_passes/feature_gate.rs

@@ -121,6 +121,14 @@ impl<'a> PostExpansionVisitor<'a> {
                     "amdgpu-kernel ABI is experimental and subject to change"
                 );
             }
+            "avr-interrupt" | "avr-non-blocking-interrupt" => {
+                gate_feature_post!(
+                    &self,
+                    abi_avr_interrupt,
+                    span,
+                    "avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change"
+                );
+            }
             "efiapi" => {
                 gate_feature_post!(
                     &self,

src/librustc_codegen_llvm/abi.rs

@@ -375,6 +375,8 @@ impl<'tcx> FnAbiLlvmExt<'tcx> for FnAbi<'tcx, Ty<'tcx>> {
         match self.conv {
             Conv::C | Conv::Rust => llvm::CCallConv,
             Conv::AmdGpuKernel => llvm::AmdGpuKernel,
+            Conv::AvrInterrupt => llvm::AvrInterrupt,
+            Conv::AvrNonBlockingInterrupt => llvm::AvrNonBlockingInterrupt,
             Conv::ArmAapcs => llvm::ArmAapcsCallConv,
             Conv::Msp430Intr => llvm::Msp430Intr,
             Conv::PtxKernel => llvm::PtxKernel,

src/librustc_codegen_llvm/llvm/ffi.rs

@@ -45,6 +45,8 @@ pub enum CallConv {
     X86_64_Win64 = 79,
     X86_VectorCall = 80,
     X86_Intr = 83,
+    AvrNonBlockingInterrupt = 84,
+    AvrInterrupt = 85,
     AmdGpuKernel = 91,
 }
 

src/librustc_feature/active.rs

@@ -574,6 +574,9 @@ declare_features! (
     /// No longer treat an unsafe function as an unsafe block.
     (active, unsafe_block_in_unsafe_fn, "1.45.0", Some(71668), None),
 
+    /// Allows `extern "avr-interrupt" fn()` and `extern "avr-non-blocking-interrupt" fn()`.
+    (active, abi_avr_interrupt, "1.45.0", Some(69664), None),
+
     // -------------------------------------------------------------------------
     // feature-group-end: actual feature gates
     // -------------------------------------------------------------------------

src/librustc_llvm/build.rs

@@ -78,6 +78,7 @@ fn main() {
         "arm",
         "aarch64",
         "amdgpu",
+        "avr",
         "mips",
         "powerpc",
         "systemz",

src/librustc_llvm/lib.rs

@@ -76,6 +76,14 @@ pub fn initialize_available_targets() {
         LLVMInitializeAMDGPUAsmPrinter,
         LLVMInitializeAMDGPUAsmParser
     );
+    init_target!(
+        llvm_component = "avr",
+        LLVMInitializeAVRTargetInfo,
+        LLVMInitializeAVRTarget,
+        LLVMInitializeAVRTargetMC,
+        LLVMInitializeAVRAsmPrinter,
+        LLVMInitializeAVRAsmParser
+    );
     init_target!(
         llvm_component = "mips",
         LLVMInitializeMipsTargetInfo,

src/librustc_middle/ty/layout.rs

@@ -2529,6 +2529,8 @@ where
             Msp430Interrupt => Conv::Msp430Intr,
             X86Interrupt => Conv::X86Intr,
             AmdGpuKernel => Conv::AmdGpuKernel,
+            AvrInterrupt => Conv::AvrInterrupt,
+            AvrNonBlockingInterrupt => Conv::AvrNonBlockingInterrupt,
 
             // These API constants ought to be more specific...
             Cdecl => Conv::C,