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soft-fp: Use temporary variable in FP_FRAC_SUB_3/FP_FRAC_SUB_4

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In FRAC_SUB_3(R, X, Y) and FRAC_SUB_4(R,, X, Y), it reference both
the X[N] and X[N] after R[N] have been set. If one of the X and Y is
the same address with R, the result of the calculation is wrong,
because the value of the original X and Y are overwritten.

In glibc, there are two places use FRAC_SUB and occurs the overlap.
The first is _FP_DIV_MEAT_N_loop in op-common.h, it uses the source
_FP_DIV_MEAT_N_loop_u as the destination. This macro only be used
when N is one(_FP_DIV_MEAT_1_loop) and then the _FP_FRAC_SUB_##wc
extend to _FP_FRAC_SUB_1 in this macro. so it also work because
_FP_FRAC_SUB_1 has no overlap problem in its implementation.
The second places is _FP_DIV_MEAT_4_udiv, the original value of X##_f[0]
is overwritten before the calculatation.

In FRAC_SUB_1 and FRAC_SUB_2, there don't refer the source after
destination have been set, so they have no problem.

After this modification, we can pass the soft floating testing of glibc
testsuites on RV32.

	* soft-fp/op-4.h (_FP_FRAC_SUB_3, _FP_FRAC_SUB_4): Use temporary
	variable to avoid overlap arguments.
This commit is contained in:
Zong Li 2018-11-01 17:34:39 +00:00 committed by Joseph Myers
parent eac4405af0
commit ff48ea6787
2 changed files with 40 additions and 28 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
2018-11-01 Zong Li <zong@andestech.com>
* soft-fp/op-4.h (_FP_FRAC_SUB_3, _FP_FRAC_SUB_4): Use temporary
variable to avoid overlap arguments.
2018-11-01 Joseph Myers <joseph@codesourcery.com>
* posix/bug-regex22.c (main): Use puts with distinct error

33
soft-fp/op-4.h
View File

@ -699,14 +699,17 @@
# define __FP_FRAC_SUB_3(r2, r1, r0, x2, x1, x0, y2, y1, y0) \
do \
{ \
_FP_W_TYPE __FP_FRAC_SUB_3_tmp[2]; \
_FP_W_TYPE __FP_FRAC_SUB_3_c1, __FP_FRAC_SUB_3_c2; \
r0 = x0 - y0; \
__FP_FRAC_SUB_3_c1 = r0 > x0; \
r1 = x1 - y1; \
__FP_FRAC_SUB_3_c2 = r1 > x1; \
r1 -= __FP_FRAC_SUB_3_c1; \
__FP_FRAC_SUB_3_tmp[0] = x0 - y0; \
__FP_FRAC_SUB_3_c1 = __FP_FRAC_SUB_3_tmp[0] > x0; \
__FP_FRAC_SUB_3_tmp[1] = x1 - y1; \
__FP_FRAC_SUB_3_c2 = __FP_FRAC_SUB_3_tmp[1] > x1; \
__FP_FRAC_SUB_3_tmp[1] -= __FP_FRAC_SUB_3_c1; \
__FP_FRAC_SUB_3_c2 |= __FP_FRAC_SUB_3_c1 && (y1 == x1); \
r2 = x2 - y2 - __FP_FRAC_SUB_3_c2; \
r1 = __FP_FRAC_SUB_3_tmp[1]; \
r0 = __FP_FRAC_SUB_3_tmp[0]; \
} \
while (0)
#endif
@ -715,19 +718,23 @@
# define __FP_FRAC_SUB_4(r3, r2, r1, r0, x3, x2, x1, x0, y3, y2, y1, y0) \
do \
{ \
_FP_W_TYPE __FP_FRAC_SUB_4_tmp[3]; \
_FP_W_TYPE __FP_FRAC_SUB_4_c1, __FP_FRAC_SUB_4_c2; \
_FP_W_TYPE __FP_FRAC_SUB_4_c3; \
r0 = x0 - y0; \
__FP_FRAC_SUB_4_c1 = r0 > x0; \
r1 = x1 - y1; \
__FP_FRAC_SUB_4_c2 = r1 > x1; \
r1 -= __FP_FRAC_SUB_4_c1; \
__FP_FRAC_SUB_4_tmp[0] = x0 - y0; \
__FP_FRAC_SUB_4_c1 = __FP_FRAC_SUB_4_tmp[0] > x0; \
__FP_FRAC_SUB_4_tmp[1] = x1 - y1; \
__FP_FRAC_SUB_4_c2 = __FP_FRAC_SUB_4_tmp[1] > x1; \
__FP_FRAC_SUB_4_tmp[1] -= __FP_FRAC_SUB_4_c1; \
__FP_FRAC_SUB_4_c2 |= __FP_FRAC_SUB_4_c1 && (y1 == x1); \
r2 = x2 - y2; \
__FP_FRAC_SUB_4_c3 = r2 > x2; \
r2 -= __FP_FRAC_SUB_4_c2; \
__FP_FRAC_SUB_4_tmp[2] = x2 - y2; \
__FP_FRAC_SUB_4_c3 = __FP_FRAC_SUB_4_tmp[2] > x2; \
__FP_FRAC_SUB_4_tmp[2] -= __FP_FRAC_SUB_4_c2; \
__FP_FRAC_SUB_4_c3 |= __FP_FRAC_SUB_4_c2 && (y2 == x2); \
r3 = x3 - y3 - __FP_FRAC_SUB_4_c3; \
r2 = __FP_FRAC_SUB_4_tmp[2]; \
r1 = __FP_FRAC_SUB_4_tmp[1]; \
r0 = __FP_FRAC_SUB_4_tmp[0]; \
} \
while (0)
#endif