Execution testcases c-torture/execute/920929-1.c and
c-torture/execute/built-in-setjmp.c began failing on mingw32 in late August,
coincident with merge of IRA into trunk.
In both cases, the execution tests pass if -fno-ira is added to command line.
The problem appears to be in the call of the target stack-probing code
(__chkstk) in cygwin.asm from allocate_stack_worker instruction. __chkstk has
unusual calling convention, with the input argument as well as the
output passed in eax.
>From i386.md:
(define_insn "allocate_stack_worker_32"
[(set (match_operand:SI 0 "register_operand" "+a")
(unspec_volatile:SI [(match_dup 0)] UNSPECV_STACK_PROBE))
(set (reg:SI SP_REG) (minus:SI (reg:SI SP_REG) (match_dup 0)))
(clobber (reg:CC FLAGS_REG))]
"!TARGET_64BIT && TARGET_STACK_PROBE"
"call\t___chkstk"
[(set_attr "type" "multi")
(set_attr "length" "5")])
The relevant part of the output of
gcc -S -O -funroll-all-loops 920929-1.c -o 920929-1-IRA.s:
f:
pushl %ebp
movl %esp, %ebp
pushl %ebx
subl $4, %esp
movl 8(%ebp), %edx
call ___chkstk
leal 15(%esp), %ecx
andl $-16, %ecx
testl %edx, %edx
...
__chkstk allocates only 1 byte and the code segfault on the first
attempt to assign a double to the allocated array.
The output, with -fno-ira
gcc -S -O -funroll-all-loops -fno-ira 920929-1.c -o 920929-1-NOIRA.s:
_f:
pushl %ebp
movl %esp, %ebp
pushl %ebx
subl $4, %esp
movl 8(%ebp), %ebx
leal 30(,%ebx,8), %eax
andl $-16, %eax
call ___chkstk
leal 15(%esp), %eax
movl %eax, %edx
andl $-16, %edx
testl %ebx, %ebx
__chkstk allocates 816 bytes
A comparison of built-in-setjmp.c with amd without -fno-ira switch also shows
incorrect input to __chkstk
Probably related to these failure is miscompilation of the C++ compiler
code cp/pt.c, which segfaults following call to alloca in
process_partial_specialization when building libstdc++. If cp/pt.c is
compiled with -fno-ira, libstdc++ builds successfully.
Danny
--
Summary: [4.4.0 regression]__builtin_alloca (vs IRA?) testsuite
failures on mingw32
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: dannysmith at users dot sourceforge dot net
GCC build triplet: i686-pc-mingw32
GCC host triplet: i686-pc-mingw32
GCC target triplet: i686-pc-mingw32
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38130
