[clang][CodeGen][AVR] Fix a crash in AVRABIInfo (#131976)

fixes #131967

Author: benshi001

clang/lib/CodeGen/Targets/AVR.cpp

@@ -59,7 +59,7 @@ class AVRABIInfo : public DefaultABIInfo {
     unsigned TySize = getContext().getTypeSize(Ty);
 
     // An int8 type argument always costs two registers like an int16.
-    if (TySize == 8 && NumRegs >= 2) {
+    if (TySize == 8 && NumRegs >= 2 && Ty->isIntegralOrEnumerationType()) {
       NumRegs -= 2;
       return ABIArgInfo::getExtend(Ty);
     }

clang/test/CodeGen/avr/argument.c

@@ -114,3 +114,13 @@ struct s15 fooa(char a, char b) {
   x.arr[1] = b;
   return x;
 }
+
+struct s8_t {
+  char a;
+};
+
+// AVR:  define {{.*}} i8 @foob(i8 {{.*}})
+// TINY: define {{.*}} i8 @foob(i8 {{.*}})
+char foob(struct s8_t a) {
+  return a.a + 1;
+}