Auto merge of #106619 - agausmann:avr-object-file, r=nagisa

Fix unset e_flags in ELF files generated for AVR targets Closes #106576 ~~Sort-of blocked by gimli-rs/object#500~~ (merged) I'm not sure whether the list of AVR CPU names is okay here. Maybe it could be moved out-of-line to improve the readability of the function.
rust-lang · Jun 30, 2023 · af9df2f · af9df2f
2 parents b4591cb + a7158ec
commit af9df2f
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Showing 5 changed files with 350 additions and 1 deletion.
diff --git a/Cargo.lock b/Cargo.lock
@@ -4069,6 +4069,7 @@ name = "rustc_target"
 version = "0.0.0"
 dependencies = [
  "bitflags",
+ "object 0.31.1",
  "rustc_abi",
  "rustc_data_structures",
  "rustc_feature",

diff --git a/compiler/rustc_codegen_ssa/src/back/metadata.rs b/compiler/rustc_codegen_ssa/src/back/metadata.rs
@@ -20,7 +20,7 @@ use rustc_metadata::EncodedMetadata;
 use rustc_session::cstore::MetadataLoader;
 use rustc_session::Session;
 use rustc_target::abi::Endian;
-use rustc_target::spec::{RelocModel, Target};
+use rustc_target::spec::{ef_avr_arch, RelocModel, Target};
 
 /// The default metadata loader. This is used by cg_llvm and cg_clif.
 ///
@@ -287,6 +287,11 @@ pub(crate) fn create_object_file(sess: &Session) -> Option<write::Object<'static
             // Source: https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html#_e_flags_identifies_abi_type_and_version
             elf::EF_LARCH_OBJABI_V1 | elf::EF_LARCH_ABI_DOUBLE_FLOAT
         }
+        Architecture::Avr => {
+            // Resolve the ISA revision and set
+            // the appropriate EF_AVR_ARCH flag.
+            ef_avr_arch(&sess.target.options.cpu)
+        }
         _ => 0,
     };
     // adapted from LLVM's `MCELFObjectTargetWriter::getOSABI`

diff --git a/compiler/rustc_target/Cargo.toml b/compiler/rustc_target/Cargo.toml
@@ -14,3 +14,8 @@ rustc_feature = { path = "../rustc_feature" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
+
+[dependencies.object]
+version = "0.31.1"
+default-features = false
+features = ["elf"]
diff --git a/compiler/rustc_target/src/spec/avr_gnu_base.rs b/compiler/rustc_target/src/spec/avr_gnu_base.rs
@@ -1,4 +1,5 @@
 use crate::spec::{Cc, LinkerFlavor, Lld, RelocModel, Target, TargetOptions};
+use object::elf;
 
 /// A base target for AVR devices using the GNU toolchain.
 ///
@@ -29,3 +30,339 @@ pub fn target(target_cpu: &'static str, mmcu: &'static str) -> Target {
         },
     }
 }
+
+/// Resolve the value of the EF_AVR_ARCH field for AVR ELF files, given the
+/// name of the target CPU / MCU.
+///
+/// In ELF files using the AVR architecture, the lower 7 bits of the e_flags
+/// field is a code that identifies the "ISA revision" of the object code.
+///
+/// This flag is generally set by AVR compilers in their output ELF files,
+/// and linkers like avr-ld check this flag in all of their input files to
+/// make sure they are compiled with the same ISA revision.
+pub fn ef_avr_arch(target_cpu: &str) -> u32 {
+    // Adapted from llvm-project/llvm/lib/target/AVR/AVRDevices.td
+    match target_cpu {
+        // Generic MCUs
+        "avr1" => elf::EF_AVR_ARCH_AVR1,
+        "avr2" => elf::EF_AVR_ARCH_AVR2,
+        "avr25" => elf::EF_AVR_ARCH_AVR25,
+        "avr3" => elf::EF_AVR_ARCH_AVR3,
+        "avr31" => elf::EF_AVR_ARCH_AVR31,
+        "avr35" => elf::EF_AVR_ARCH_AVR35,
+        "avr4" => elf::EF_AVR_ARCH_AVR4,
+        "avr5" => elf::EF_AVR_ARCH_AVR5,
+        "avr51" => elf::EF_AVR_ARCH_AVR51,
+        "avr6" => elf::EF_AVR_ARCH_AVR6,
+        "avrxmega1" => elf::EF_AVR_ARCH_XMEGA1,
+        "avrxmega2" => elf::EF_AVR_ARCH_XMEGA2,
+        "avrxmega3" => elf::EF_AVR_ARCH_XMEGA3,
+        "avrxmega4" => elf::EF_AVR_ARCH_XMEGA4,
+        "avrxmega5" => elf::EF_AVR_ARCH_XMEGA5,
+        "avrxmega6" => elf::EF_AVR_ARCH_XMEGA6,
+        "avrxmega7" => elf::EF_AVR_ARCH_XMEGA7,
+        "avrtiny" => elf::EF_AVR_ARCH_AVRTINY,
+
+        // Specific MCUs
+        "at90s1200" => elf::EF_AVR_ARCH_AVR1,
+        "attiny11" => elf::EF_AVR_ARCH_AVR1,
+        "attiny12" => elf::EF_AVR_ARCH_AVR1,
+        "attiny15" => elf::EF_AVR_ARCH_AVR1,
+        "attiny28" => elf::EF_AVR_ARCH_AVR1,
+        "at90s2313" => elf::EF_AVR_ARCH_AVR2,
+        "at90s2323" => elf::EF_AVR_ARCH_AVR2,
+        "at90s2333" => elf::EF_AVR_ARCH_AVR2,
+        "at90s2343" => elf::EF_AVR_ARCH_AVR2,
+        "attiny22" => elf::EF_AVR_ARCH_AVR2,
+        "attiny26" => elf::EF_AVR_ARCH_AVR2,
+        "at86rf401" => elf::EF_AVR_ARCH_AVR25,
+        "at90s4414" => elf::EF_AVR_ARCH_AVR2,
+        "at90s4433" => elf::EF_AVR_ARCH_AVR2,
+        "at90s4434" => elf::EF_AVR_ARCH_AVR2,
+        "at90s8515" => elf::EF_AVR_ARCH_AVR2,
+        "at90c8534" => elf::EF_AVR_ARCH_AVR2,
+        "at90s8535" => elf::EF_AVR_ARCH_AVR2,
+        "ata5272" => elf::EF_AVR_ARCH_AVR25,
+        "ata6616c" => elf::EF_AVR_ARCH_AVR25,
+        "attiny13" => elf::EF_AVR_ARCH_AVR25,
+        "attiny13a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny2313" => elf::EF_AVR_ARCH_AVR25,
+        "attiny2313a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny24" => elf::EF_AVR_ARCH_AVR25,
+        "attiny24a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny4313" => elf::EF_AVR_ARCH_AVR25,
+        "attiny44" => elf::EF_AVR_ARCH_AVR25,
+        "attiny44a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny84" => elf::EF_AVR_ARCH_AVR25,
+        "attiny84a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny25" => elf::EF_AVR_ARCH_AVR25,
+        "attiny45" => elf::EF_AVR_ARCH_AVR25,
+        "attiny85" => elf::EF_AVR_ARCH_AVR25,
+        "attiny261" => elf::EF_AVR_ARCH_AVR25,
+        "attiny261a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny441" => elf::EF_AVR_ARCH_AVR25,
+        "attiny461" => elf::EF_AVR_ARCH_AVR25,
+        "attiny461a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny841" => elf::EF_AVR_ARCH_AVR25,
+        "attiny861" => elf::EF_AVR_ARCH_AVR25,
+        "attiny861a" => elf::EF_AVR_ARCH_AVR25,
+        "attiny87" => elf::EF_AVR_ARCH_AVR25,
+        "attiny43u" => elf::EF_AVR_ARCH_AVR25,
+        "attiny48" => elf::EF_AVR_ARCH_AVR25,
+        "attiny88" => elf::EF_AVR_ARCH_AVR25,
+        "attiny828" => elf::EF_AVR_ARCH_AVR25,
+        "at43usb355" => elf::EF_AVR_ARCH_AVR3,
+        "at76c711" => elf::EF_AVR_ARCH_AVR3,
+        "atmega103" => elf::EF_AVR_ARCH_AVR31,
+        "at43usb320" => elf::EF_AVR_ARCH_AVR31,
+        "attiny167" => elf::EF_AVR_ARCH_AVR35,
+        "at90usb82" => elf::EF_AVR_ARCH_AVR35,
+        "at90usb162" => elf::EF_AVR_ARCH_AVR35,
+        "ata5505" => elf::EF_AVR_ARCH_AVR35,
+        "ata6617c" => elf::EF_AVR_ARCH_AVR35,
+        "ata664251" => elf::EF_AVR_ARCH_AVR35,
+        "atmega8u2" => elf::EF_AVR_ARCH_AVR35,
+        "atmega16u2" => elf::EF_AVR_ARCH_AVR35,
+        "atmega32u2" => elf::EF_AVR_ARCH_AVR35,
+        "attiny1634" => elf::EF_AVR_ARCH_AVR35,
+        "atmega8" => elf::EF_AVR_ARCH_AVR4,
+        "ata6289" => elf::EF_AVR_ARCH_AVR4,
+        "atmega8a" => elf::EF_AVR_ARCH_AVR4,
+        "ata6285" => elf::EF_AVR_ARCH_AVR4,
+        "ata6286" => elf::EF_AVR_ARCH_AVR4,
+        "ata6612c" => elf::EF_AVR_ARCH_AVR4,
+        "atmega48" => elf::EF_AVR_ARCH_AVR4,
+        "atmega48a" => elf::EF_AVR_ARCH_AVR4,
+        "atmega48pa" => elf::EF_AVR_ARCH_AVR4,
+        "atmega48pb" => elf::EF_AVR_ARCH_AVR4,
+        "atmega48p" => elf::EF_AVR_ARCH_AVR4,
+        "atmega88" => elf::EF_AVR_ARCH_AVR4,
+        "atmega88a" => elf::EF_AVR_ARCH_AVR4,
+        "atmega88p" => elf::EF_AVR_ARCH_AVR4,
+        "atmega88pa" => elf::EF_AVR_ARCH_AVR4,
+        "atmega88pb" => elf::EF_AVR_ARCH_AVR4,
+        "atmega8515" => elf::EF_AVR_ARCH_AVR4,
+        "atmega8535" => elf::EF_AVR_ARCH_AVR4,
+        "atmega8hva" => elf::EF_AVR_ARCH_AVR4,
+        "at90pwm1" => elf::EF_AVR_ARCH_AVR4,
+        "at90pwm2" => elf::EF_AVR_ARCH_AVR4,
+        "at90pwm2b" => elf::EF_AVR_ARCH_AVR4,
+        "at90pwm3" => elf::EF_AVR_ARCH_AVR4,
+        "at90pwm3b" => elf::EF_AVR_ARCH_AVR4,
+        "at90pwm81" => elf::EF_AVR_ARCH_AVR4,
+        "ata5702m322" => elf::EF_AVR_ARCH_AVR5,
+        "ata5782" => elf::EF_AVR_ARCH_AVR5,
+        "ata5790" => elf::EF_AVR_ARCH_AVR5,
+        "ata5790n" => elf::EF_AVR_ARCH_AVR5,
+        "ata5791" => elf::EF_AVR_ARCH_AVR5,
+        "ata5795" => elf::EF_AVR_ARCH_AVR5,
+        "ata5831" => elf::EF_AVR_ARCH_AVR5,
+        "ata6613c" => elf::EF_AVR_ARCH_AVR5,
+        "ata6614q" => elf::EF_AVR_ARCH_AVR5,
+        "ata8210" => elf::EF_AVR_ARCH_AVR5,
+        "ata8510" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega161" => elf::EF_AVR_ARCH_AVR5,
+        "atmega162" => elf::EF_AVR_ARCH_AVR5,
+        "atmega163" => elf::EF_AVR_ARCH_AVR5,
+        "atmega164a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega164p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega164pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega165" => elf::EF_AVR_ARCH_AVR5,
+        "atmega165a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega165p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega165pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega168" => elf::EF_AVR_ARCH_AVR5,
+        "atmega168a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega168p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega168pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega168pb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega169" => elf::EF_AVR_ARCH_AVR5,
+        "atmega169a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega169p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega169pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega323" => elf::EF_AVR_ARCH_AVR5,
+        "atmega324a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega324p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega324pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega324pb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega325" => elf::EF_AVR_ARCH_AVR5,
+        "atmega325a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega325p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega325pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3250" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3250a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3250p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3250pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega328" => elf::EF_AVR_ARCH_AVR5,
+        "atmega328p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega328pb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega329" => elf::EF_AVR_ARCH_AVR5,
+        "atmega329a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega329p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega329pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3290" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3290a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3290p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega3290pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega406" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega640" => elf::EF_AVR_ARCH_AVR5,
+        "atmega644" => elf::EF_AVR_ARCH_AVR5,
+        "atmega644a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega644p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega644pa" => elf::EF_AVR_ARCH_AVR5,
+        "atmega645" => elf::EF_AVR_ARCH_AVR5,
+        "atmega645a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega645p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega649" => elf::EF_AVR_ARCH_AVR5,
+        "atmega649a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega649p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega6450" => elf::EF_AVR_ARCH_AVR5,
+        "atmega6450a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega6450p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega6490" => elf::EF_AVR_ARCH_AVR5,
+        "atmega6490a" => elf::EF_AVR_ARCH_AVR5,
+        "atmega6490p" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64rfr2" => elf::EF_AVR_ARCH_AVR5,
+        "atmega644rfr2" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16hva" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16hva2" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16hvb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16hvbrevb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32hvb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32hvbrevb" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64hve" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64hve2" => elf::EF_AVR_ARCH_AVR5,
+        "at90can32" => elf::EF_AVR_ARCH_AVR5,
+        "at90can64" => elf::EF_AVR_ARCH_AVR5,
+        "at90pwm161" => elf::EF_AVR_ARCH_AVR5,
+        "at90pwm216" => elf::EF_AVR_ARCH_AVR5,
+        "at90pwm316" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32c1" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64c1" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16m1" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32m1" => elf::EF_AVR_ARCH_AVR5,
+        "atmega64m1" => elf::EF_AVR_ARCH_AVR5,
+        "atmega16u4" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32u4" => elf::EF_AVR_ARCH_AVR5,
+        "atmega32u6" => elf::EF_AVR_ARCH_AVR5,
+        "at90usb646" => elf::EF_AVR_ARCH_AVR5,
+        "at90usb647" => elf::EF_AVR_ARCH_AVR5,
+        "at90scr100" => elf::EF_AVR_ARCH_AVR5,
+        "at94k" => elf::EF_AVR_ARCH_AVR5,
+        "m3000" => elf::EF_AVR_ARCH_AVR5,
+        "atmega128" => elf::EF_AVR_ARCH_AVR51,
+        "atmega128a" => elf::EF_AVR_ARCH_AVR51,
+        "atmega1280" => elf::EF_AVR_ARCH_AVR51,
+        "atmega1281" => elf::EF_AVR_ARCH_AVR51,
+        "atmega1284" => elf::EF_AVR_ARCH_AVR51,
+        "atmega1284p" => elf::EF_AVR_ARCH_AVR51,
+        "atmega128rfa1" => elf::EF_AVR_ARCH_AVR51,
+        "atmega128rfr2" => elf::EF_AVR_ARCH_AVR51,
+        "atmega1284rfr2" => elf::EF_AVR_ARCH_AVR51,
+        "at90can128" => elf::EF_AVR_ARCH_AVR51,
+        "at90usb1286" => elf::EF_AVR_ARCH_AVR51,
+        "at90usb1287" => elf::EF_AVR_ARCH_AVR51,
+        "atmega2560" => elf::EF_AVR_ARCH_AVR6,
+        "atmega2561" => elf::EF_AVR_ARCH_AVR6,
+        "atmega256rfr2" => elf::EF_AVR_ARCH_AVR6,
+        "atmega2564rfr2" => elf::EF_AVR_ARCH_AVR6,
+        "atxmega16a4" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega16a4u" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega16c4" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega16d4" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32a4" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32a4u" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32c3" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32c4" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32d3" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32d4" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega32e5" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega16e5" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega8e5" => elf::EF_AVR_ARCH_XMEGA2,
+        "atxmega64a3" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64a3u" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64a4u" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64b1" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64b3" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64c3" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64d3" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64d4" => elf::EF_AVR_ARCH_XMEGA4,
+        "atxmega64a1" => elf::EF_AVR_ARCH_XMEGA5,
+        "atxmega64a1u" => elf::EF_AVR_ARCH_XMEGA5,
+        "atxmega128a3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128a3u" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128b1" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128b3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128c3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128d3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128d4" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega192a3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega192a3u" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega192c3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega192d3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega256a3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega256a3u" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega256a3b" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega256a3bu" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega256c3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega256d3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega384c3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega384d3" => elf::EF_AVR_ARCH_XMEGA6,
+        "atxmega128a1" => elf::EF_AVR_ARCH_XMEGA7,
+        "atxmega128a1u" => elf::EF_AVR_ARCH_XMEGA7,
+        "atxmega128a4u" => elf::EF_AVR_ARCH_XMEGA7,
+        "attiny4" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny5" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny9" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny10" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny20" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny40" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny102" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny104" => elf::EF_AVR_ARCH_AVRTINY,
+        "attiny202" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny402" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny204" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny404" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny804" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1604" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny406" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny806" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1606" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny807" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1607" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny212" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny412" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny214" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny414" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny814" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1614" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny416" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny816" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1616" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny3216" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny417" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny817" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1617" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny3217" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1624" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1626" => elf::EF_AVR_ARCH_XMEGA3,
+        "attiny1627" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega808" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega809" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega1608" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega1609" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega3208" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega3209" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega4808" => elf::EF_AVR_ARCH_XMEGA3,
+        "atmega4809" => elf::EF_AVR_ARCH_XMEGA3,
+
+        // Unknown target CPU => Unspecified/generic code
+        _ => 0,
+    }
+}
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
@@ -62,6 +62,7 @@ mod android_base;
 mod apple_base;
 pub use apple_base::deployment_target as current_apple_deployment_target;
 mod avr_gnu_base;
+pub use avr_gnu_base::ef_avr_arch;
 mod bpf_base;
 mod dragonfly_base;
 mod freebsd_base;