From: Taylor Simpson <tsimpson@quicinc.com>
To: qemu-devel@nongnu.org
Cc: peter.maydell@linaro.org, tsimpson@quicinc.com,
richard.henderson@linaro.org, f4bug@amsat.org
Subject: [PULL 01/30] Hexagon HVX (target/hexagon) README
Date: Sun, 31 Oct 2021 11:42:40 -0500 [thread overview]
Message-ID: <1635698589-31849-2-git-send-email-tsimpson@quicinc.com> (raw)
In-Reply-To: <1635698589-31849-1-git-send-email-tsimpson@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
---
target/hexagon/README | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 80 insertions(+), 1 deletion(-)
diff --git a/target/hexagon/README b/target/hexagon/README
index b0b2435..372e247 100644
--- a/target/hexagon/README
+++ b/target/hexagon/README
@@ -1,9 +1,13 @@
Hexagon is Qualcomm's very long instruction word (VLIW) digital signal
-processor(DSP).
+processor(DSP). We also support Hexagon Vector eXtensions (HVX). HVX
+is a wide vector coprocessor designed for high performance computer vision,
+image processing, machine learning, and other workloads.
The following versions of the Hexagon core are supported
Scalar core: v67
https://developer.qualcomm.com/downloads/qualcomm-hexagon-v67-programmer-s-reference-manual
+ HVX extension: v66
+ https://developer.qualcomm.com/downloads/qualcomm-hexagon-v66-hvx-programmer-s-reference-manual
We presented an overview of the project at the 2019 KVM Forum.
https://kvmforum2019.sched.com/event/Tmwc/qemu-hexagon-automatic-translation-of-the-isa-manual-pseudcode-to-tiny-code-instructions-of-a-vliw-architecture-niccolo-izzo-revng-taylor-simpson-qualcomm-innovation-center
@@ -124,6 +128,71 @@ There are also cases where we brute force the TCG code generation.
Instructions with multiple definitions are examples. These require special
handling because qemu helpers can only return a single value.
+For HVX vectors, the generator behaves slightly differently. The wide vectors
+won't fit in a TCGv or TCGv_i64, so we pass TCGv_ptr variables to pass the
+address to helper functions. Here's an example for an HVX vector-add-word
+istruction.
+ static void generate_V6_vaddw(
+ CPUHexagonState *env,
+ DisasContext *ctx,
+ Insn *insn,
+ Packet *pkt)
+ {
+ const int VdN = insn->regno[0];
+ const intptr_t VdV_off =
+ ctx_future_vreg_off(ctx, VdN, 1, true);
+ TCGv_ptr VdV = tcg_temp_local_new_ptr();
+ tcg_gen_addi_ptr(VdV, cpu_env, VdV_off);
+ const int VuN = insn->regno[1];
+ const intptr_t VuV_off =
+ vreg_src_off(ctx, VuN);
+ TCGv_ptr VuV = tcg_temp_local_new_ptr();
+ const int VvN = insn->regno[2];
+ const intptr_t VvV_off =
+ vreg_src_off(ctx, VvN);
+ TCGv_ptr VvV = tcg_temp_local_new_ptr();
+ tcg_gen_addi_ptr(VuV, cpu_env, VuV_off);
+ tcg_gen_addi_ptr(VvV, cpu_env, VvV_off);
+ TCGv slot = tcg_constant_tl(insn->slot);
+ gen_helper_V6_vaddw(cpu_env, VdV, VuV, VvV, slot);
+ tcg_temp_free(slot);
+ gen_log_vreg_write(ctx, VdV_off, VdN, EXT_DFL, insn->slot, false);
+ ctx_log_vreg_write(ctx, VdN, EXT_DFL, false);
+ tcg_temp_free_ptr(VdV);
+ tcg_temp_free_ptr(VuV);
+ tcg_temp_free_ptr(VvV);
+ }
+
+Notice that we also generate a variable named <operand>_off for each operand of
+the instruction. This makes it easy to override the instruction semantics with
+functions from tcg-op-gvec.h. Here's the override for this instruction.
+ #define fGEN_TCG_V6_vaddw(SHORTCODE) \
+ tcg_gen_gvec_add(MO_32, VdV_off, VuV_off, VvV_off, \
+ sizeof(MMVector), sizeof(MMVector))
+
+Finally, we notice that the override doesn't use the TCGv_ptr variables, so
+we don't generate them when an override is present. Here is what we generate
+when the override is present.
+ static void generate_V6_vaddw(
+ CPUHexagonState *env,
+ DisasContext *ctx,
+ Insn *insn,
+ Packet *pkt)
+ {
+ const int VdN = insn->regno[0];
+ const intptr_t VdV_off =
+ ctx_future_vreg_off(ctx, VdN, 1, true);
+ const int VuN = insn->regno[1];
+ const intptr_t VuV_off =
+ vreg_src_off(ctx, VuN);
+ const int VvN = insn->regno[2];
+ const intptr_t VvV_off =
+ vreg_src_off(ctx, VvN);
+ fGEN_TCG_V6_vaddw({ fHIDE(int i;) fVFOREACH(32, i) { VdV.w[i] = VuV.w[i] + VvV.w[i] ; } });
+ gen_log_vreg_write(ctx, VdV_off, VdN, EXT_DFL, insn->slot, false);
+ ctx_log_vreg_write(ctx, VdN, EXT_DFL, false);
+ }
+
In addition to instruction semantics, we use a generator to create the decode
tree. This generation is also a two step process. The first step is to run
target/hexagon/gen_dectree_import.c to produce
@@ -140,6 +209,7 @@ runtime information for each thread and contains stuff like the GPR and
predicate registers.
macros.h
+mmvec/macros.h
The Hexagon arch lib relies heavily on macros for the instruction semantics.
This is a great advantage for qemu because we can override them for different
@@ -203,6 +273,15 @@ During runtime, the following fields in CPUHexagonState (see cpu.h) are used
pred_written boolean indicating if predicate was written
mem_log_stores record of the stores (indexed by slot)
+For Hexagon Vector eXtensions (HVX), the following fields are used
+ VRegs Vector registers
+ future_VRegs Registers to be stored during packet commit
+ tmp_VRegs Temporary registers *not* stored during commit
+ VRegs_updated Mask of predicated vector writes
+ QRegs Q (vector predicate) registers
+ future_QRegs Registers to be stored during packet commit
+ QRegs_updated Mask of predicated vector writes
+
*** Debugging ***
You can turn on a lot of debugging by changing the HEX_DEBUG macro to 1 in
--
2.7.4
next prev parent reply other threads:[~2021-10-31 16:51 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-31 16:42 [PULL 00/30] Hexagon HVX (target/hexagon) patch series Taylor Simpson
2021-10-31 16:42 ` Taylor Simpson [this message]
2021-10-31 16:42 ` [PULL 02/30] Hexagon HVX (target/hexagon) add Hexagon Vector eXtensions (HVX) to core Taylor Simpson
2021-10-31 16:42 ` [PULL 03/30] Hexagon HVX (target/hexagon) register names Taylor Simpson
2021-10-31 16:42 ` [PULL 04/30] Hexagon HVX (target/hexagon) instruction attributes Taylor Simpson
2021-10-31 16:42 ` [PULL 05/30] Hexagon HVX (target/hexagon) macros Taylor Simpson
2021-10-31 16:42 ` [PULL 06/30] Hexagon HVX (target/hexagon) import macro definitions Taylor Simpson
2021-10-31 16:42 ` [PULL 07/30] Hexagon HVX (target/hexagon) semantics generator Taylor Simpson
2021-10-31 16:42 ` [PULL 08/30] Hexagon HVX (target/hexagon) semantics generator - part 2 Taylor Simpson
2021-10-31 16:42 ` [PULL 09/30] Hexagon HVX (target/hexagon) C preprocessor for decode tree Taylor Simpson
2021-10-31 16:42 ` [PULL 10/30] Hexagon HVX (target/hexagon) instruction utility functions Taylor Simpson
2021-10-31 16:42 ` [PULL 11/30] Hexagon HVX (target/hexagon) helper functions Taylor Simpson
2021-10-31 16:42 ` [PULL 12/30] Hexagon HVX (target/hexagon) TCG generation Taylor Simpson
2021-10-31 16:42 ` [PULL 13/30] Hexagon HVX (target/hexagon) helper overrides infrastructure Taylor Simpson
2021-10-31 16:42 ` [PULL 14/30] Hexagon HVX (target/hexagon) helper overrides for histogram instructions Taylor Simpson
2021-10-31 16:42 ` [PULL 15/30] Hexagon HVX (target/hexagon) helper overrides - vector assign & cmov Taylor Simpson
2021-10-31 16:42 ` [PULL 16/30] Hexagon HVX (target/hexagon) helper overrides - vector add & sub Taylor Simpson
2021-10-31 16:42 ` [PULL 17/30] Hexagon HVX (target/hexagon) helper overrides - vector shifts Taylor Simpson
2021-10-31 16:42 ` [PULL 18/30] Hexagon HVX (target/hexagon) helper overrides - vector max/min Taylor Simpson
2021-10-31 16:42 ` [PULL 19/30] Hexagon HVX (target/hexagon) helper overrides - vector logical ops Taylor Simpson
2021-10-31 16:42 ` [PULL 20/30] Hexagon HVX (target/hexagon) helper overrides - vector compares Taylor Simpson
2021-10-31 16:43 ` [PULL 21/30] Hexagon HVX (target/hexagon) helper overrides - vector splat and abs Taylor Simpson
2021-10-31 16:43 ` [PULL 22/30] Hexagon HVX (target/hexagon) helper overrides - vector loads Taylor Simpson
2021-10-31 16:43 ` [PULL 23/30] Hexagon HVX (target/hexagon) helper overrides - vector stores Taylor Simpson
2021-10-31 16:43 ` [PULL 24/30] Hexagon HVX (target/hexagon) import semantics Taylor Simpson
2021-10-31 16:43 ` [PULL 25/30] Hexagon HVX (target/hexagon) instruction decoding Taylor Simpson
2021-10-31 16:43 ` [PULL 26/30] Hexagon HVX (target/hexagon) import instruction encodings Taylor Simpson
2021-10-31 16:43 ` [PULL 27/30] Hexagon HVX (tests/tcg/hexagon) vector_add_int test Taylor Simpson
2021-10-31 16:43 ` [PULL 28/30] Hexagon HVX (tests/tcg/hexagon) hvx_misc test Taylor Simpson
2021-11-01 10:33 ` Philippe Mathieu-Daudé
2021-11-01 13:43 ` Richard Henderson
2021-11-01 14:09 ` Taylor Simpson
2021-11-01 14:17 ` Philippe Mathieu-Daudé
2021-11-01 15:02 ` Richard Henderson
2021-11-02 16:05 ` Taylor Simpson
2021-11-02 16:41 ` Alex Bennée
2021-11-02 16:53 ` Taylor Simpson
2021-11-03 13:31 ` Alex Bennée
2021-11-03 15:22 ` Hexagon toolchain update vs linux-user signals Richard Henderson
2021-10-31 16:43 ` [PULL 29/30] Hexagon HVX (tests/tcg/hexagon) scatter_gather test Taylor Simpson
2021-10-31 16:43 ` [PULL 30/30] Hexagon HVX (tests/tcg/hexagon) histogram test Taylor Simpson
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