[clang][Driver][AVR] Reject c/c++ compilation for avr1 devices

avr-gcc also rejects since these devices has no SRAM.

Fixes #96881

Author: benshi001

clang/docs/ReleaseNotes.rst

@@ -598,6 +598,8 @@ WebAssembly Support
 AVR Support
 ^^^^^^^^^^^
 
+- Reject C/C++ compilation for avr1 devices which has no SRAM.
+
 DWARF Support in Clang
 ----------------------
 

clang/lib/Driver/ToolChains/AVR.cpp

@@ -400,6 +400,14 @@ void AVRToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
 void AVRToolChain::addClangTargetOptions(
     const llvm::opt::ArgList &DriverArgs, llvm::opt::ArgStringList &CC1Args,
     Action::OffloadKind DeviceOffloadKind) const {
+  // Reject C/C++ compilation for avr1 devices since they have no SRAM.
+  const Driver &D = getDriver();
+  std::string CPU = getCPUName(D, DriverArgs, getTriple());
+  std::optional<StringRef> FamilyName = GetMCUFamilyName(CPU);
+  if (CPU == "avr1" || (FamilyName && *FamilyName == "avr1"))
+    D.Diag(diag::err_drv_opt_unsupported_input_type)
+        << "-mmcu=" + CPU << "c/c++";
+
   // By default, use `.ctors` (not `.init_array`), as required by libgcc, which
   // runs constructors/destructors on AVR.
   if (!DriverArgs.hasFlag(options::OPT_fuse_init_array,

clang/test/Driver/avr-mmcu.c

@@ -1,8 +1,7 @@
 // A test for the propagation of the -mmcu option to -cc1 and -cc1as
 
-// RUN: %clang -### --target=avr -mmcu=attiny11 -save-temps %s 2>&1 | FileCheck -check-prefix=CHECK0 %s
-// CHECK0: "-cc1" {{.*}} "-target-cpu" "attiny11"
-// CHECK0: "-cc1as" {{.*}} "-target-cpu" "attiny11"
+// RUN: not %clang -### --target=avr -mmcu=attiny11 %s 2>&1 | FileCheck -check-prefix=CHECK0 %s
+// CHECK0: error: '-mmcu=attiny11' invalid for input of type c/c++
 
 // RUN: %clang -### --target=avr -mmcu=at90s2313 -save-temps %s 2>&1 | FileCheck -check-prefix=CHECK1 %s
 // CHECK1: "-cc1" {{.*}} "-target-cpu" "at90s2313"