lavc/riscv: don't set vxrm if unnecessary

While narrowing clip is nominally a rounding operation, the rounding mode has no arithmetic consequence if the right shift is by zero bits.

Rémi Denis-Courmont committed 2 years ago

Commit bbfc0ac1 parent e42a0762 files · +2 −4Browse files

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@@ -31,14 +31,13 @@ func ff_h263_h_loop_filter_rvv, zve32x · 30 unmodified lines
31	31	vssseg4e8.v v8, (a0), a1
32	32	ret
33	33	1:
34		− csrwi vxrm, 0
35		−2: auipc t1, %pcrel_hi(ff_h263_loop_filter_strength)
	34	+ auipc t1, %pcrel_hi(ff_h263_loop_filter_strength)
36	35	vwsubu.vv v14, v10, v9 # p2 - p1
37	36	add t1, t1, a2
38	37	vwsubu.vv v12, v8, v11 # p0 - p3
39	38	vsetvli zero, zero, e16, m1, ta, mu
40	39	vsll.vi v14, v14, 2
41		− lbu t1, %pcrel_lo(2b)(t1) # strength
	40	+ lbu t1, %pcrel_lo(1b)(t1) # strength
42	41	vadd.vv v16, v12, v14
43	42	# Divide by 8 toward 0. v16 is a signed 10-bit value at this point.
44	43	vsrl.vi v18, v16, 16 - 3 # v18 = (v16 < 0) ? 7 : 0

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