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Re: [Qemu-devel] [PATCH 05/10] target-arm: A64: Add "Floating-point data
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH 05/10] target-arm: A64: Add "Floating-point data-processing (3 source)" insns |
Date: |
Mon, 30 Dec 2013 07:15:26 -0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 |
On 12/28/2013 01:49 PM, Peter Maydell wrote:
> + /* These are fused multiply-add, and must be done as one
> + * floating point operation with no rounding between the
> + * multiplication and addition steps.
> + * NB that doing the negations here as separate steps is
> + * correct : an input NaN should come out with its sign bit
> + * flipped if it is a negated-input.
> + */
> + if (o1 == true) {
> + gen_helper_vfp_negs(tcg_op3, tcg_op3);
> + }
> +
> + if (o0 != o1) {
> + gen_helper_vfp_negs(tcg_op1, tcg_op1);
> + }
> +
> + gen_helper_vfp_muladds(tcg_res, tcg_op1, tcg_op2, tcg_op3, fpst);
Do you really get the wrong result passing the appropriate
float_muladd_negate_* constant?
I realize that the A32 target doesn't do this either, but shouldn't that be
cleaned up? It's certainly confusing to the reader, wondering why they aren't
used...
r~
- [Qemu-devel] [PATCH 09/10] target-arm: A64: Add support for floating point cond select, (continued)
- [Qemu-devel] [PATCH 09/10] target-arm: A64: Add support for floating point cond select, Peter Maydell, 2013/12/28
- [Qemu-devel] [PATCH 08/10] target-arm: A64: Add support for floating point conditional compare, Peter Maydell, 2013/12/28
- [Qemu-devel] [PATCH 03/10] target-arm: Use VFP_BINOP macro for min, max, minnum, maxnum, Peter Maydell, 2013/12/28
- [Qemu-devel] [PATCH 02/10] target-arm: A64: Fix vector register access on bigendian hosts, Peter Maydell, 2013/12/28
- [Qemu-devel] [PATCH 05/10] target-arm: A64: Add "Floating-point data-processing (3 source)" insns, Peter Maydell, 2013/12/28
- Re: [Qemu-devel] [PATCH 05/10] target-arm: A64: Add "Floating-point data-processing (3 source)" insns,
Richard Henderson <=
- [Qemu-devel] [PATCH 10/10] target-arm: Give the FPSCR rounding modes names, Peter Maydell, 2013/12/28