[AVR] Define __ELF__

[aykevl]

Summary

This symbol is defined in avr-gcc. Because AVR normally uses the ELF format, define the symbol unconditionally.

This patch is needed to get Clang to compile compiler-rt.

[MaskRay]

The test/clang/Preprocessor/ directory may make more sense for such tests. Is it time to create a target-specific sub directory test/clang/Preprocessor/AVR/?

[rjmccall]

I agree that these tests are in the wrong directory; please prepare a patch that moves them. This patch is okay to go, though.

[aykevl]

Okay, I have committed this patch and created a new patch to move the files: https://reviews.llvm.org/D78163

clang/lib/Basic/Targets/AVR.cpp

for (const MCUInfo &Info : AVRMcus)
     Values.push_back(Info.Name);
 }
 
 void AVRTargetInfo::getTargetDefines(const LangOptions &Opts,
                                      MacroBuilder &Builder) const {
   Builder.defineMacro("AVR");
   Builder.defineMacro("__AVR");
   Builder.defineMacro("__AVR__");
+  Builder.defineMacro("__ELF__");
 
   if (!this->CPU.empty()) {
     auto It = llvm::find_if(
         AVRMcus, [&](const MCUInfo &Info) { return Info.Name == this->CPU; });
 
     if (It != std::end(AVRMcus))
       Builder.defineMacro(It->DefineName);
   }
 }

clang/test/CodeGen/avr/target-cpu-defines/atmega328p.c

 // REQUIRES: avr-registered-target
 // RUN: %clang_cc1 -E -dM -triple avr-unknown-unknown -target-cpu atmega328p /dev/null | FileCheck -match-full-lines %s
 
 // CHECK: #define AVR 1
 // CHECK: #define __AVR 1
 // CHECK: #define __AVR_ATmega328P__ 1
 // CHECK: #define __AVR__ 1
+// CHECK: #define __ELF__ 1

clang/test/CodeGen/avr/target-cpu-defines/attiny104.c

 // REQUIRES: avr-registered-target
 // RUN: %clang_cc1 -E -dM -triple avr-unknown-unknown -target-cpu attiny104 /dev/null | FileCheck -match-full-lines %s
 
 // CHECK: #define AVR 1
 // CHECK: #define __AVR 1
 // CHECK: #define __AVR_ATtiny104__ 1
 // CHECK: #define __AVR__ 1
+// CHECK: #define __ELF__ 1

clang/test/CodeGen/avr/target-cpu-defines/common.c

 // REQUIRES: avr-registered-target
 // RUN: %clang_cc1 -E -dM -triple avr-unknown-unknown /dev/null | FileCheck -match-full-lines %s
 
 // CHECK: #define AVR 1
 // CHECK: #define __AVR 1
 // CHECK: #define __AVR__ 1
+// CHECK: #define __ELF__ 1