Hexagon (target/hexagon) Use QEMU decodetree (16-bit instructions)
Section 10.3 of the Hexagon V73 Programmer's Reference Manual
A duplex is encoded as a 32-bit instruction with bits [15:14] set to 00.
The sub-instructions that comprise a duplex are encoded as 13-bit fields
in the duplex.
Create a decoder for each subinstruction class (a, l1, l2, s1, s2).
Extend gen_trans_funcs.py to handle all instructions rather than
filter by instruction class.
There is a g_assert_not_reached() in decode_insns() in decode.c to
verify we never try to use the old decoder on 16-bit instructions.
Signed-off-by: Taylor Simpson <ltaylorsimpson@gmail.com>
Reviewed-by: Brian Cain <bcain@quicinc.com>
Message-Id: <20240115221443.365287-3-ltaylorsimpson@gmail.com>
Signed-off-by: Brian Cain <bcain@quicinc.com>
diff --git a/target/hexagon/README b/target/hexagon/README
index 1b2a4d0..746ebec 100644
--- a/target/hexagon/README
+++ b/target/hexagon/README
@@ -195,6 +195,7 @@
Step 2 is to import iset.py into target/hexagon/gen_decodetree.py to produce
<BUILD_DIR>/target/hexagon/normal_decode_generated
<BUILD_DIR>/target/hexagon/hvx_decode_generated
+ <BUILD_DIR>/target/hexagon/subinsn_*_decode_generated
Step 3 is to process the above files with QEMU's decodetree.py to produce
<BUILD_DIR>/target/hexagon/decode_*_generated.c.inc
Step 4 is to import iset.py into target/hexagon/gen_trans_funcs.py to produce
diff --git a/target/hexagon/decode.c b/target/hexagon/decode.c
index bddad1f..160b23a 100644
--- a/target/hexagon/decode.c
+++ b/target/hexagon/decode.c
@@ -60,6 +60,7 @@
}
DECODE_MAPPED(R_16)
DECODE_MAPPED(R_8)
+DECODE_MAPPED(R__8)
/* Helper function for decodetree_trans_funcs_generated.c.inc */
static int shift_left(DisasContext *ctx, int x, int n, int immno)
@@ -77,6 +78,13 @@
#include "decode_normal_generated.c.inc"
#include "decode_hvx_generated.c.inc"
+/* Include the generated decoder for 16 bit insn */
+#include "decode_subinsn_a_generated.c.inc"
+#include "decode_subinsn_l1_generated.c.inc"
+#include "decode_subinsn_l2_generated.c.inc"
+#include "decode_subinsn_s1_generated.c.inc"
+#include "decode_subinsn_s2_generated.c.inc"
+
/* Include the generated helpers for the decoder */
#include "decodetree_trans_funcs_generated.c.inc"
@@ -790,6 +798,63 @@
}
}
+/*
+ * Section 10.3 of the Hexagon V73 Programmer's Reference Manual
+ *
+ * A duplex is encoded as a 32-bit instruction with bits [15:14] set to 00.
+ * The sub-instructions that comprise a duplex are encoded as 13-bit fields
+ * in the duplex.
+ *
+ * Per table 10-4, the 4-bit duplex iclass is encoded in bits 31:29, 13
+ */
+static uint32_t get_duplex_iclass(uint32_t encoding)
+{
+ uint32_t iclass = extract32(encoding, 13, 1);
+ iclass = deposit32(iclass, 1, 3, extract32(encoding, 29, 3));
+ return iclass;
+}
+
+/*
+ * Per table 10-5, the duplex ICLASS field values that specify the group of
+ * each sub-instruction in a duplex
+ *
+ * This table points to the decode instruction for each entry in the table
+ */
+typedef bool (*subinsn_decode_func)(DisasContext *ctx, uint16_t insn);
+typedef struct {
+ subinsn_decode_func decode_slot0_subinsn;
+ subinsn_decode_func decode_slot1_subinsn;
+} subinsn_decode_groups;
+
+static const subinsn_decode_groups decode_groups[16] = {
+ [0x0] = { decode_subinsn_l1, decode_subinsn_l1 },
+ [0x1] = { decode_subinsn_l2, decode_subinsn_l1 },
+ [0x2] = { decode_subinsn_l2, decode_subinsn_l2 },
+ [0x3] = { decode_subinsn_a, decode_subinsn_a },
+ [0x4] = { decode_subinsn_l1, decode_subinsn_a },
+ [0x5] = { decode_subinsn_l2, decode_subinsn_a },
+ [0x6] = { decode_subinsn_s1, decode_subinsn_a },
+ [0x7] = { decode_subinsn_s2, decode_subinsn_a },
+ [0x8] = { decode_subinsn_s1, decode_subinsn_l1 },
+ [0x9] = { decode_subinsn_s1, decode_subinsn_l2 },
+ [0xa] = { decode_subinsn_s1, decode_subinsn_s1 },
+ [0xb] = { decode_subinsn_s2, decode_subinsn_s1 },
+ [0xc] = { decode_subinsn_s2, decode_subinsn_l1 },
+ [0xd] = { decode_subinsn_s2, decode_subinsn_l2 },
+ [0xe] = { decode_subinsn_s2, decode_subinsn_s2 },
+ [0xf] = { NULL, NULL }, /* Reserved */
+};
+
+static uint16_t get_slot0_subinsn(uint32_t encoding)
+{
+ return extract32(encoding, 0, 13);
+}
+
+static uint16_t get_slot1_subinsn(uint32_t encoding)
+{
+ return extract32(encoding, 16, 13);
+}
+
static unsigned int
decode_insns(DisasContext *ctx, Insn *insn, uint32_t encoding)
{
@@ -805,8 +870,28 @@
table = &dectree_table_DECODE_ROOT_32;
g_assert_not_reached();
} else {
+ uint32_t iclass = get_duplex_iclass(encoding);
+ unsigned int slot0_subinsn = get_slot0_subinsn(encoding);
+ unsigned int slot1_subinsn = get_slot1_subinsn(encoding);
+ subinsn_decode_func decode_slot0_subinsn =
+ decode_groups[iclass].decode_slot0_subinsn;
+ subinsn_decode_func decode_slot1_subinsn =
+ decode_groups[iclass].decode_slot1_subinsn;
+
+ /* The slot1 subinsn needs to be in the packet first */
+ if (decode_slot1_subinsn(ctx, slot1_subinsn)) {
+ insn->generate = opcode_genptr[insn->opcode];
+ insn->iclass = iclass_bits(encoding);
+ ctx->insn = ++insn;
+ if (decode_slot0_subinsn(ctx, slot0_subinsn)) {
+ insn->generate = opcode_genptr[insn->opcode];
+ insn->iclass = iclass_bits(encoding);
+ return 2;
+ }
+ }
/* start with EE table - duplex instructions */
table = &dectree_table_DECODE_ROOT_EE;
+ g_assert_not_reached();
}
return decode_insns_tablewalk(insn, table, encoding);
}
diff --git a/target/hexagon/gen_decodetree.py b/target/hexagon/gen_decodetree.py
index 9634554..a4fcd62 100755
--- a/target/hexagon/gen_decodetree.py
+++ b/target/hexagon/gen_decodetree.py
@@ -96,8 +96,10 @@
## A2_add ..................-.....---..... @A2_add
##
def gen_decodetree_file(f, class_to_decode):
+ is_subinsn = class_to_decode.startswith("SUBINSN_")
f.write(f"## DO NOT MODIFY - This file is generated by {sys.argv[0]}\n\n")
- f.write("%PP\t14:2\n\n")
+ if not is_subinsn:
+ f.write("%PP\t14:2\n\n")
for tag in sorted(encs.keys(), key=iset.tags.index):
if skip_tag(tag, class_to_decode):
continue
@@ -108,6 +110,10 @@
f"## {tag}:\t{enc_str}\n"
"##\n")
+ # The subinstructions come with a 13-bit encoding, but
+ # decodetree.py needs 16 bits
+ if is_subinsn:
+ enc_str = "---" + enc_str
regs = ordered_unique(regre.findall(iset.iset[tag]["syntax"]))
imms = ordered_unique(immre.findall(iset.iset[tag]["syntax"]))
@@ -174,7 +180,9 @@
imm_letter = "i" if imm_type.islower() else "I"
f.write(f" {imm_type}{imm_letter}=%{tag}_{imm_type}{imm_letter}")
- f.write(" %PP\n")
+ if not is_subinsn:
+ f.write(" %PP")
+ f.write("\n")
# Replace the 0s and 1s with .
enc_str = enc_str.replace("0", ".").replace("1", ".")
diff --git a/target/hexagon/gen_trans_funcs.py b/target/hexagon/gen_trans_funcs.py
index c907131..53e844a 100755
--- a/target/hexagon/gen_trans_funcs.py
+++ b/target/hexagon/gen_trans_funcs.py
@@ -40,11 +40,6 @@
return sorted(set(l), key=l.index)
-def skip_tag(tag, classes):
- enc_class = iset.iset[tag]["enc_class"]
- return enc_class not in classes
-
-
def code_fmt(txt):
return textwrap.indent(textwrap.dedent(txt), " ")
@@ -76,12 +71,9 @@
## return true;
## }
##
-def gen_trans_funcs(f, classes):
+def gen_trans_funcs(f):
f.write(f"/* DO NOT MODIFY - This file is generated by {sys.argv[0]} */\n\n")
for tag in sorted(encs.keys(), key=iset.tags.index):
- if skip_tag(tag, classes):
- continue
-
regs = ordered_unique(regre.findall(iset.iset[tag]["syntax"]))
imms = ordered_unique(immre.findall(iset.iset[tag]["syntax"]))
@@ -129,4 +121,4 @@
if __name__ == "__main__":
hex_common.read_semantics_file(sys.argv[1])
with open(sys.argv[2], "w") as f:
- gen_trans_funcs(f, { "NORMAL", "EXT_mmvec" })
+ gen_trans_funcs(f)
diff --git a/target/hexagon/meson.build b/target/hexagon/meson.build
index 831bd57..1bd1ebc 100644
--- a/target/hexagon/meson.build
+++ b/target/hexagon/meson.build
@@ -154,6 +154,51 @@
)
hexagon_ss.add(hvx_decode_generated)
+subinsn_a_decode_generated = custom_target(
+ 'subinsn_a_decode_generated',
+ output: 'subinsn_a_decode_generated',
+ depends: [iset_py, semantics_generated],
+ env: {'PYTHONPATH': meson.current_build_dir()},
+ command: [python, files('gen_decodetree.py'), semantics_generated, 'SUBINSN_A', '@OUTPUT@'],
+)
+hexagon_ss.add(subinsn_a_decode_generated)
+
+subinsn_l1_decode_generated = custom_target(
+ 'subinsn_l1_decode_generated',
+ output: 'subinsn_l1_decode_generated',
+ depends: [iset_py, semantics_generated],
+ env: {'PYTHONPATH': meson.current_build_dir()},
+ command: [python, files('gen_decodetree.py'), semantics_generated, 'SUBINSN_L1', '@OUTPUT@'],
+)
+hexagon_ss.add(subinsn_l1_decode_generated)
+
+subinsn_l2_decode_generated = custom_target(
+ 'subinsn_l2_decode_generated',
+ output: 'subinsn_l2_decode_generated',
+ depends: [iset_py, semantics_generated],
+ env: {'PYTHONPATH': meson.current_build_dir()},
+ command: [python, files('gen_decodetree.py'), semantics_generated, 'SUBINSN_L2', '@OUTPUT@'],
+)
+hexagon_ss.add(subinsn_l2_decode_generated)
+
+subinsn_s1_decode_generated = custom_target(
+ 'subinsn_s1_decode_generated',
+ output: 'subinsn_s1_decode_generated',
+ depends: [iset_py, semantics_generated],
+ env: {'PYTHONPATH': meson.current_build_dir()},
+ command: [python, files('gen_decodetree.py'), semantics_generated, 'SUBINSN_S1', '@OUTPUT@'],
+)
+hexagon_ss.add(subinsn_s1_decode_generated)
+
+subinsn_s2_decode_generated = custom_target(
+ 'subinsn_s2_decode_generated',
+ output: 'subinsn_s2_decode_generated',
+ depends: [iset_py, semantics_generated],
+ env: {'PYTHONPATH': meson.current_build_dir()},
+ command: [python, files('gen_decodetree.py'), semantics_generated, 'SUBINSN_S2', '@OUTPUT@'],
+)
+hexagon_ss.add(subinsn_s2_decode_generated)
+
#
# Run the QEMU decodetree.py script to produce the instruction decoder
#
@@ -176,6 +221,51 @@
)
hexagon_ss.add(decode_hvx_generated)
+decode_subinsn_a_generated = custom_target(
+ 'decode_subinsn_a_generated.c.inc',
+ output: 'decode_subinsn_a_generated.c.inc',
+ input: subinsn_a_decode_generated,
+ env: {'PYTHONPATH': meson.current_build_dir()},
+ command: [python, files(decodetree_py), subinsn_a_decode_generated, ['--static-decode=decode_subinsn_a', '--insnwidth=16'], '-o', '@OUTPUT@'],
+)
+hexagon_ss.add(decode_subinsn_a_generated)
+
+decode_subinsn_l1_generated = custom_target(
+ 'decode_subinsn_l1_generated.c.inc',
+ output: 'decode_subinsn_l1_generated.c.inc',
+ input: subinsn_l1_decode_generated,
+ env: {'PYTHONPATH': meson.current_build_dir()},
+ command: [python, files(decodetree_py), subinsn_l1_decode_generated, ['--static-decode=decode_subinsn_l1', '--insnwidth=16'], '-o', '@OUTPUT@'],
+)
+hexagon_ss.add(decode_subinsn_l1_generated)
+
+decode_subinsn_l2_generated = custom_target(
+ 'decode_subinsn_l2_generated.c.inc',
+ output: 'decode_subinsn_l2_generated.c.inc',
+ input: subinsn_l2_decode_generated,
+ env: {'PYTHONPATH': meson.current_build_dir()},
+ command: [python, files(decodetree_py), subinsn_l2_decode_generated, ['--static-decode=decode_subinsn_l2', '--insnwidth=16'], '-o', '@OUTPUT@'],
+)
+hexagon_ss.add(decode_subinsn_l2_generated)
+
+decode_subinsn_s1_generated = custom_target(
+ 'decode_subinsn_s1_generated.c.inc',
+ output: 'decode_subinsn_s1_generated.c.inc',
+ input: subinsn_s1_decode_generated,
+ env: {'PYTHONPATH': meson.current_build_dir()},
+ command: [python, files(decodetree_py), subinsn_s1_decode_generated, ['--static-decode=decode_subinsn_s1', '--insnwidth=16'], '-o', '@OUTPUT@'],
+)
+hexagon_ss.add(decode_subinsn_s1_generated)
+
+decode_subinsn_s2_generated = custom_target(
+ 'decode_subinsn_s2_generated.c.inc',
+ output: 'decode_subinsn_s2_generated.c.inc',
+ input: subinsn_s2_decode_generated,
+ env: {'PYTHONPATH': meson.current_build_dir()},
+ command: [python, files(decodetree_py), subinsn_s2_decode_generated, ['--static-decode=decode_subinsn_s2', '--insnwidth=16'], '-o', '@OUTPUT@'],
+)
+hexagon_ss.add(decode_subinsn_s2_generated)
+
#
# Generate the trans_* functions that the decoder will use
#
