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target/arm: Correct names of VFP VFNMA and VFNMS insns

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In vfp.decode we have the names of the VFNMA and VFNMS instructions
the wrong way around.  The architecture says that bit 6 is the 'op'
bit, which is 1 for VFNMA and 0 for VFNMS, but we label these two
lines of decode the other way around.  This doesn't cause any
user-visible problem because in the handling of these functions in
translate-vfp.c we give VFNMA the behaviour specified for VFNMS and
vice-versa, but it's confusing when reading the code.

Switch the names of the VFP VFNMA and VFNMS instructions in
the decode file and flip the behaviour also.

NB: the instructions VFMA and VFMS *are* decoded with op=0 for
VFMA and op=1 for VFMS; the confusion probably arose because
we assumed VFNMA and VFNMS to be the same way around.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2536
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20240830152156.2046590-1-peter.maydell@linaro.org
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Peter Maydell 2024-08-30 16:21:56 +01:00
parent c2a33809e5
commit 76dd36660b
2 changed files with 10 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
target/arm/tcg/translate-vfp.c
View File

@ -2190,8 +2190,8 @@ static bool do_vfm_sp(DisasContext *s, arg_VFMA_sp *a, bool neg_n, bool neg_d)
static bool do_vfm_dp(DisasContext *s, arg_VFMA_dp *a, bool neg_n, bool neg_d)
{
/*
* VFNMA : fd = muladd(-fd, fn, fm)
* VFNMS : fd = muladd(-fd, -fn, fm)
* VFNMA : fd = muladd(-fd, -fn, fm)
* VFNMS : fd = muladd(-fd, fn, fm)
* VFMA : fd = muladd( fd, fn, fm)
* VFMS : fd = muladd( fd, -fn, fm)
*
@ -2262,8 +2262,8 @@ static bool do_vfm_dp(DisasContext *s, arg_VFMA_dp *a, bool neg_n, bool neg_d)
#define MAKE_VFM_TRANS_FNS(PREC) \
MAKE_ONE_VFM_TRANS_FN(VFMA, PREC, false, false) \
MAKE_ONE_VFM_TRANS_FN(VFMS, PREC, true, false) \
MAKE_ONE_VFM_TRANS_FN(VFNMA, PREC, false, true) \
MAKE_ONE_VFM_TRANS_FN(VFNMS, PREC, true, true)
MAKE_ONE_VFM_TRANS_FN(VFNMS, PREC, false, true) \
MAKE_ONE_VFM_TRANS_FN(VFNMA, PREC, true, true)
MAKE_VFM_TRANS_FNS(hp)
MAKE_VFM_TRANS_FNS(sp)

12
target/arm/tcg/vfp.decode
View File

@ -141,18 +141,18 @@ VDIV_dp ---- 1110 1.00 .... .... 1011 .0.0 .... @vfp_dnm_d
VFMA_hp ---- 1110 1.10 .... .... 1001 .0. 0 .... @vfp_dnm_s
VFMS_hp ---- 1110 1.10 .... .... 1001 .1. 0 .... @vfp_dnm_s
VFNMA_hp ---- 1110 1.01 .... .... 1001 .0. 0 .... @vfp_dnm_s
VFNMS_hp ---- 1110 1.01 .... .... 1001 .1. 0 .... @vfp_dnm_s
VFNMS_hp ---- 1110 1.01 .... .... 1001 .0. 0 .... @vfp_dnm_s
VFNMA_hp ---- 1110 1.01 .... .... 1001 .1. 0 .... @vfp_dnm_s
VFMA_sp ---- 1110 1.10 .... .... 1010 .0. 0 .... @vfp_dnm_s
VFMS_sp ---- 1110 1.10 .... .... 1010 .1. 0 .... @vfp_dnm_s
VFNMA_sp ---- 1110 1.01 .... .... 1010 .0. 0 .... @vfp_dnm_s
VFNMS_sp ---- 1110 1.01 .... .... 1010 .1. 0 .... @vfp_dnm_s
VFNMS_sp ---- 1110 1.01 .... .... 1010 .0. 0 .... @vfp_dnm_s
VFNMA_sp ---- 1110 1.01 .... .... 1010 .1. 0 .... @vfp_dnm_s
VFMA_dp ---- 1110 1.10 .... .... 1011 .0.0 .... @vfp_dnm_d
VFMS_dp ---- 1110 1.10 .... .... 1011 .1.0 .... @vfp_dnm_d
VFNMA_dp ---- 1110 1.01 .... .... 1011 .0.0 .... @vfp_dnm_d
VFNMS_dp ---- 1110 1.01 .... .... 1011 .1.0 .... @vfp_dnm_d
VFNMS_dp ---- 1110 1.01 .... .... 1011 .0.0 .... @vfp_dnm_d
VFNMA_dp ---- 1110 1.01 .... .... 1011 .1.0 .... @vfp_dnm_d
VMOV_imm_hp ---- 1110 1.11 .... .... 1001 0000 .... \
vd=%vd_sp imm=%vmov_imm