https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110611
Bug ID: 110611
Summary: X86 is not honouring POINTERS_EXTEND_UNSIGNED in m32
code.
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: iains at gcc dot gnu.org
Target Milestone: ---
I've made this target but not sure exactly where it lies - the gimplifier
output looks suspect already - so maybe it's gimplifer/frontend.
this code is distilled from a version of GDB (7.12) where 'bar' is a system
call that breaks with a sign-extended pointer...
the x86 backend sets:
gcc/config/i386/i386.h:#define POINTERS_EXTEND_UNSIGNED 1
which ought, according to gccint mean that pointers get sign-extended...
t.c ====
typedef unsigned long long uint64_t;
typedef uint64_t another_t;
typedef unsigned char byte;
extern void bar (another_t y, another_t z);
void foo (byte *p)
{
another_t x = (another_t)p;
bar ((another_t) p, x);
}
===
build : $(compiler) -m32 t.c -S -fdump-tree-gimple -Wall -Wextra
* If built by the GCC compiler, we get warnings like;
warning: cast from pointer to integer of different size
[-Wpointer-to-int-cast]
9 | another_t x = (another_t)p;
* if built by G++ we get no warnings
However, in both cases, the generated assembler sign-extends *p => x and the
first arg to bar.
gimple:
void foo (byte * p)
{
another_t x;
p.0_1 = (int) p;
x = (another_t) p.0_1;
p.1_2 = (int) p;
_3 = (long long unsigned int) p.1_2;
bar (_3, x);
}
maybe the combination of 'perhaps wrong' user code, plus the maze of typedefs
is confusing something.
