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author | Luis Machado <luis.machado@arm.com> | 2022-01-04 14:06:36 -0300 |
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committer | Luis Machado <luis.machado@arm.com> | 2022-03-14 10:38:32 +0000 |
commit | bab22d0640914384d467e09c3e796585fd08e7c6 (patch) | |
tree | 96c9d0148f50a7686eab88239889a1d3c7b782a7 /gdb/aarch64-tdep.c | |
parent | d4661bf0e978da6e8b8a9cb792c9e82bfab403f0 (diff) | |
download | binutils-bab22d0640914384d467e09c3e796585fd08e7c6.zip binutils-bab22d0640914384d467e09c3e796585fd08e7c6.tar.gz binutils-bab22d0640914384d467e09c3e796585fd08e7c6.tar.bz2 |
[aarch64/arm] Properly extract the return value returned in memory
When running gdb.cp/non-trivial-retval.exp, the following shows up for
both aarch64-linux and armhf-linux:
Breakpoint 3, f1 (i1=23, i2=100) at src/gdb/testsuite/gdb.cp/non-trivial-retval.cc:35
35 A a;
(gdb) finish
Run till exit from #0 f1 (i1=23, i2=100) at src/gdb/testsuite/gdb.cp/non-trivial-retval.cc:35
main () at /src/gdb/testsuite/gdb.cp/non-trivial-retval.cc:163
163 B b = f2 (i1, i2);
Value returned is $6 = {a = -11952}
(gdb)
The return value should be {a = 123} instead. This happens because the
backends don't extract the return value from the correct location. GDB should
fetch a pointer to the memory location from X8 for aarch64 and r0 for armhf.
With the patch, gdb.cp/non-trivial-retval.exp has full passes on
aarch64-linux and armhf-linux on Ubuntu 20.04/18.04.
The problem only shows up with the "finish" command. The "call" command
works correctly and displays the correct return value.
This is also related to PR gdb/28681
(https://sourceware.org/bugzilla/show_bug.cgi?id=28681) and fixes FAIL's in
gdb.ada/mi_var_array.exp.
A new testcase is provided, and it exercises GDB's ability to "finish" a
function that returns a large struct (> 16 bytes) and display the
contents of this struct correctly. This has always been incorrect for
these backends, but no testcase exercised this particular scenario.
Diffstat (limited to 'gdb/aarch64-tdep.c')
-rw-r--r-- | gdb/aarch64-tdep.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c index b3efb3e..3f3a652 100644 --- a/gdb/aarch64-tdep.c +++ b/gdb/aarch64-tdep.c @@ -2362,7 +2362,8 @@ aarch64_return_in_memory (struct gdbarch *gdbarch, struct type *type) return 0; } - if (TYPE_LENGTH (type) > 16) + if (TYPE_LENGTH (type) > 16 + || !language_pass_by_reference (type).trivially_copyable) { /* PCS B.6 Aggregates larger than 16 bytes are passed by invisible reference. */ @@ -2474,8 +2475,24 @@ aarch64_return_value (struct gdbarch *gdbarch, struct value *func_value, { if (aarch64_return_in_memory (gdbarch, valtype)) { + /* From the AAPCS64's Result Return section: + + "Otherwise, the caller shall reserve a block of memory of + sufficient size and alignment to hold the result. The address + of the memory block shall be passed as an additional argument to + the function in x8. */ + aarch64_debug_printf ("return value in memory"); - return RETURN_VALUE_STRUCT_CONVENTION; + + if (readbuf) + { + CORE_ADDR addr; + + regcache->cooked_read (AARCH64_STRUCT_RETURN_REGNUM, &addr); + read_memory (addr, readbuf, TYPE_LENGTH (valtype)); + } + + return RETURN_VALUE_ABI_RETURNS_ADDRESS; } } |