From: Richard Henderson <richard.henderson@linaro.org>
To: "Lucas Mateus Castro(alqotel)" <lucas.araujo@eldorado.org.br>,
qemu-ppc@nongnu.org
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
"Daniel Henrique Barboza" <danielhb413@gmail.com>,
"Greg Kurz" <groug@kaod.org>,
"open list:All patches CC here" <qemu-devel@nongnu.org>,
"Cédric Le Goater" <clg@kaod.org>,
"Alex Bennée" <alex.bennee@linaro.org>,
"Aurelien Jarno" <aurelien@aurel32.net>,
"David Gibson" <david@gibson.dropbear.id.au>
Subject: Re: [RFC PATCH 5/7] target/ppc: Implemented xvf16ger*
Date: Tue, 26 Apr 2022 17:26:25 -0700 [thread overview]
Message-ID: <e5abeb2f-892f-af8d-0457-c9f8e66ddeb6@linaro.org> (raw)
In-Reply-To: <20220426125028.18844-6-lucas.araujo@eldorado.org.br>
On 4/26/22 05:50, Lucas Mateus Castro(alqotel) wrote:
> +#define VSXGER16(NAME, ORIG_T, OR_EL) \
> + void NAME(CPUPPCState *env, uint32_t a_r, uint32_t b_r, \
> + uint32_t at_r, uint32_t mask, uint32_t packed_flags) \
> + { \
> + ppc_vsr_t *at; \
> + float32 psum, aux_acc, va, vb, vc, vd; \
> + int i, j, xmsk_bit, ymsk_bit; \
> + uint8_t xmsk = mask & 0x0F; \
> + uint8_t ymsk = (mask >> 4) & 0x0F; \
> + uint8_t pmsk = (mask >> 8) & 0x3; \
> + ppc_vsr_t *b = cpu_vsr_ptr(env, b_r); \
> + ppc_vsr_t *a = cpu_vsr_ptr(env, a_r); \
> + float_status *excp_ptr = &env->fp_status; \
> + bool acc = ger_acc_flag(packed_flags); \
> + bool neg_acc = ger_neg_acc_flag(packed_flags); \
> + bool neg_mul = ger_neg_mul_flag(packed_flags); \
> + for (i = 0, xmsk_bit = 1 << 3; i < 4; i++, xmsk_bit >>= 1) { \
> + at = cpu_vsr_ptr(env, at_r + i); \
> + for (j = 0, ymsk_bit = 1 << 3; j < 4; j++, ymsk_bit >>= 1) {\
> + if ((xmsk_bit & xmsk) && (ymsk_bit & ymsk)) { \
> + va = !(pmsk & 2) ? float32_zero : \
> + GET_VSR(Vsr##OR_EL, a, \
> + 2 * i, ORIG_T, float32); \
> + vb = !(pmsk & 2) ? float32_zero : \
> + GET_VSR(Vsr##OR_EL, b, \
> + 2 * j, ORIG_T, float32); \
> + vc = !(pmsk & 1) ? float32_zero : \
> + GET_VSR(Vsr##OR_EL, a, \
> + 2 * i + 1, ORIG_T, float32);\
> + vd = !(pmsk & 1) ? float32_zero : \
> + GET_VSR(Vsr##OR_EL, b, \
> + 2 * j + 1, ORIG_T, float32);\
> + psum = float32_mul(va, vb, excp_ptr); \
> + psum = float32_muladd(vc, vd, psum, 0, excp_ptr); \
This isn't correct -- the intermediate 'prod' (the first multiply) is not rounded. I
think the correct way to implement this (barring new softfloat functions) is to compute
the intermediate product as float64 with float_round_to_odd, then float64r32_muladd into
the correct rounding mode to finish.
> + if (acc) { \
> + if (neg_mul) { \
> + psum = float32_neg(psum); \
> + } \
> + if (neg_acc) { \
> + aux_acc = float32_neg(at->VsrSF(j)); \
> + } else { \
> + aux_acc = at->VsrSF(j); \
> + } \
> + at->VsrSF(j) = float32_add(psum, aux_acc, \
> + excp_ptr); \
This one, thankfully, uses the rounded intermediate result 'msum', so is ok.
Please do convert this from a macro. Given that float16 and bfloat16 are addressed the
same, I think the only callback you need is the conversion from float16_to_float64. Drop
the bf16 accessor to ppc_vsr_t.
r~
next prev parent reply other threads:[~2022-04-27 0:27 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-26 12:50 [RFC PATCH 0/7] VSX MMA Implementation Lucas Mateus Castro(alqotel)
2022-04-26 12:50 ` [RFC PATCH 1/7] target/ppc: Implement xxm[tf]acc and xxsetaccz Lucas Mateus Castro(alqotel)
2022-04-26 22:59 ` Richard Henderson
2022-04-26 12:50 ` [RFC PATCH 2/7] target/ppc: Implemented xvi*ger* instructions Lucas Mateus Castro(alqotel)
2022-04-26 23:40 ` Richard Henderson
2022-04-27 20:24 ` Lucas Mateus Martins Araujo e Castro
2022-04-27 22:28 ` Richard Henderson
2022-04-26 12:50 ` [RFC PATCH 3/7] target/ppc: Implemented pmxvi*ger* instructions Lucas Mateus Castro(alqotel)
2022-04-26 12:50 ` [RFC PATCH 4/7] target/ppc: Implemented xvf*ger* Lucas Mateus Castro(alqotel)
2022-04-27 0:09 ` Richard Henderson
2022-04-26 12:50 ` [RFC PATCH 5/7] target/ppc: Implemented xvf16ger* Lucas Mateus Castro(alqotel)
2022-04-27 0:26 ` Richard Henderson [this message]
2022-04-27 21:11 ` Lucas Mateus Martins Araujo e Castro
2022-04-27 22:30 ` Richard Henderson
2022-04-26 12:50 ` [RFC PATCH 6/7] target/ppc: Implemented pmxvf*ger* Lucas Mateus Castro(alqotel)
2022-04-27 0:33 ` Richard Henderson
2022-04-26 12:50 ` [RFC PATCH 7/7] target/ppc: Implemented [pm]xvbf16ger2* Lucas Mateus Castro(alqotel)
2022-04-27 6:21 ` [RFC PATCH 0/7] VSX MMA Implementation Joel Stanley
2022-04-27 7:10 ` Cédric Le Goater
2022-05-05 6:06 ` Joel Stanley
2022-04-28 14:05 ` Lucas Mateus Martins Araujo e Castro
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