For the AVR target, assertions in convert_debug_memory_address cause a couple of ICEs (see PR 52472). Jakub suggested returning a NULL rtx, which works, but on debugging further, I found that expand_debug_expr appears to incorrectly compute the address space for ADDR_EXPR and MEM_REFs.
For ADDR_EXPR, TREE_TYPE(exp) is a POINTER_TYPE (always?), but in the generic address space, even if the object whose address is taken is in a different address space. expand_debug_expr takes TYPE_ADDR_SPACE(TREE_TYPE(exp)) and therefore computes the address space as generic. convert_debug_memory_address then asserts that the mode is a valid pointer mode in the address space and fails. Similarly, for MEM_REFs, TREE_TYPE(exp) is the type of the dereferenced value, and therefore checking if it is a POINTER_TYPE doesn't help for a single pointer dereference. The address space gets computed as generic even if the pointer points to a different address space. The address mode for the generic address space is passed to convert_debug_memory_address, and the assertion that that mode must match the mode of the rtx then fails. The below patch attempts to fix this by picking the right TREE_TYPE to pass to TYPE_ADDR_SPACE for MEM_REF (use type of arg 0) and ADDR_EXPR (check for pointer type and look at nested addr space). Does this look reasonable or did I get it all wrong? Regards Senthil diff --git gcc/cfgexpand.c gcc/cfgexpand.c index 8b0e466..ca78953 100644 --- gcc/cfgexpand.c +++ gcc/cfgexpand.c @@ -3941,8 +3941,8 @@ expand_debug_expr (tree exp) op0 = plus_constant (inner_mode, op0, INTVAL (op1)); } - if (POINTER_TYPE_P (TREE_TYPE (exp))) - as = TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (exp))); + if (POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (exp, 0)))) + as = TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 0)))); else as = ADDR_SPACE_GENERIC; @@ -4467,7 +4467,11 @@ expand_debug_expr (tree exp) return NULL; } - as = TYPE_ADDR_SPACE (TREE_TYPE (exp)); + if (POINTER_TYPE_P (TREE_TYPE (exp))) + as = TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (exp))); + else + as = TYPE_ADDR_SPACE (TREE_TYPE (exp)); + op0 = convert_debug_memory_address (mode, XEXP (op0, 0), as); return op0;