On 08/04/2016 08:32 AM, Renlin Li wrote:
Hi all,
In the case of PR64971
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64971),
the compiler ICE when compiling gcc.c-torture/compile/pr37433.c with
ilp32 abi.
As we know, in aarch64 ilp32, the ptr_mode is SImode while Pmode is
still DImode. It means all address should be DImode, and the backend
defines the patterns with this assumption.
The generic part expand_expr_addr_expr () function however generates a
SYMBOL_REF with SImode, it's later used as the address of a MEM rtx
pattern in a call expression. There is no matching pattern for this
SImode address, that's why gcc ICEs.
(symbol_ref/f:SI ("*.LC0") [flags 0x82] <var_decl 0x3ffb7fa1200 *.LC0>)
But here, I think what expand_expr_addr_expr does is correct. In this
particular case, expand_expr_addr_expr is not generating an address.
According to the source code, it's generating a function pointer, and
later this pointer is used in a call expression. So SImode should be
right in this case.
The behavior of the test case is, get the address of a piece of memory,
cast it into a function pointer, and call the function. IIUC, the flow
is like this:
CALL_EXPR ( NOP_EXPR (ADDR_EXPR ()))
NOP_EXPR here is to convert the address into a function pointer which
should be ptr_mode (SImode). So it's the responsibility of call expander
to convert the pointer into Pmode to create legal call rtx patern.
In the test case, there are two functions. The first function generates
function calls with a SYMBOL_REF as address, the second one generates a
REG as address. They are all of ptr_mode.
However, prepare_call_address () will convert the REG into Pmode to make
it as a legal address while SYMBOL_REF is missed. That's why I add the
code there.
And I want to change the PR64971 into a middle-end issue. The ICE
manifests in aarch64 target, but I believe this should be a generic
problem for targets which define ptr_mode different from Pmode.
There is a test case already, so I didn't add one.
aarch64-none-elf regression test Okay, aarch64-linux bootstrap Okay.
But I believe this may not help as the default abi is LP64.
It will be great if Andrew you can help to do regression test in your
aarch64 ilp32 environment.
And I double checked that, the backend fix can be removed without any
problem. It's good to expose middle-end bugs.
Okay for trunk and backport to branch 6?
gcc/ChangeLog:
2016-08-04 Renlin Li <renlin...@arm.com>
PR middle-end/64971
* calls.c (prepare_call_address): Convert funexp to Pmode when
necessary.
* config/aarch64/aarch64.md (sibcall): Remove fix for PR 64971.
(sibcall_value): Likewise.
OK.
jeff
