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tcg: Remove dh_alias indirection for dh_typecode

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The dh_alias redirect is intended to handle TCG types as distinguished
from C types.  TCG does not distinguish signed int from unsigned int,
because they are the same size.  However, we need to retain this
distinction for dh_typecode, lest we fail to extend abi types properly
for the host call parameters.

This bug was detected when running the 'arm' emulator on an s390
system. The s390 uses TCG_TARGET_EXTEND_ARGS which triggers code
in tcg_gen_callN to extend 32 bit values to 64 bits; the incorrect
sign data in the typemask for each argument caused the values to be
extended as unsigned values.

This simple program exhibits the problem:

	static volatile int num = -9;
	static volatile int den = -5;
	int main(void)
	{
		int quo = num / den;
		printf("num %d den %d quo %d\n", num, den, quo);
		exit(0);
	}

When run on the broken qemu, this results in:

	num -9 den -5 quo 0

The correct result is:

	num -9 den -5 quo 1

Fixes: 7319d83a73 ("tcg: Combine dh_is_64bit and dh_is_signed to dh_typecode")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/876
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reported-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Tested-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Tested-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2022-02-16 20:06:22 -05:00
parent 00483d3869
commit 8929906e21
5 changed files with 19 additions and 9 deletions
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19
include/exec/helper-head.h
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@ -53,13 +53,16 @@
# ifdef TARGET_LONG_BITS
# if TARGET_LONG_BITS == 32
# define dh_alias_tl i32
# define dh_typecode_tl dh_typecode_i32
# else
# define dh_alias_tl i64
# define dh_typecode_tl dh_typecode_i64
# endif
# endif
# define dh_alias_env ptr
# define dh_ctype_tl target_ulong
# define dh_alias_env ptr
# define dh_ctype_env CPUArchState *
# define dh_typecode_env dh_typecode_ptr
#endif
/* We can't use glue() here because it falls foul of C preprocessor
@ -92,18 +95,16 @@
#define dh_typecode_i64 4
#define dh_typecode_s64 5
#define dh_typecode_ptr 6
#define dh_typecode(t) glue(dh_typecode_, dh_alias(t))
#define dh_typecode_int dh_typecode_s32
#define dh_typecode_f16 dh_typecode_i32
#define dh_typecode_f32 dh_typecode_i32
#define dh_typecode_f64 dh_typecode_i64
#define dh_typecode_cptr dh_typecode_ptr
#define dh_typecode(t) dh_typecode_##t
#define dh_callflag_i32 0
#define dh_callflag_s32 0
#define dh_callflag_int 0
#define dh_callflag_i64 0
#define dh_callflag_s64 0
#define dh_callflag_f16 0
#define dh_callflag_f32 0
#define dh_callflag_f64 0
#define dh_callflag_ptr 0
#define dh_callflag_cptr dh_callflag_ptr
#define dh_callflag_void 0
#define dh_callflag_noreturn TCG_CALL_NO_RETURN
#define dh_callflag(t) glue(dh_callflag_, dh_alias(t))