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target/i386: Fix BEXTR instruction 

There were two problems here: not limiting the input to operand bits,
and not correctly handling large extraction length.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1372
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230114230542.3116013-3-richard.henderson@linaro.org>
Cc: qemu-stable@nongnu.org
Fixes: 1d0b926150 ("target/i386: move scalar 0F 38 and 0F 3A instruction to new decoder", 2022-10-18)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Richard Henderson 2023-01-14 13:05:42 -10:00 committed by Paolo Bonzini
parent 5d62d6649c
commit b14c009897
2 changed files with 23 additions and 11 deletions
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22
target/i386/tcg/emit.c.inc
View File

@ -1078,30 +1078,30 @@ static void gen_ANDN(DisasContext *s, CPUX86State *env, X86DecodedInsn *decode)
static void gen_BEXTR(DisasContext *s, CPUX86State *env, X86DecodedInsn *decode) static void gen_BEXTR(DisasContext *s, CPUX86State *env, X86DecodedInsn *decode)
{ {
MemOp ot = decode->op[0].ot; MemOp ot = decode->op[0].ot;
TCGv bound, zero; TCGv bound = tcg_constant_tl(ot == MO_64 ? 63 : 31);
TCGv zero = tcg_constant_tl(0);
TCGv mone = tcg_constant_tl(-1);
/* /*
* Extract START, and shift the operand. * Extract START, and shift the operand.
* Shifts larger than operand size get zeros. * Shifts larger than operand size get zeros.
*/ */
tcg_gen_ext8u_tl(s->A0, s->T1); tcg_gen_ext8u_tl(s->A0, s->T1);
if (TARGET_LONG_BITS == 64 && ot == MO_32) {
tcg_gen_ext32u_tl(s->T0, s->T0);
}
tcg_gen_shr_tl(s->T0, s->T0, s->A0); tcg_gen_shr_tl(s->T0, s->T0, s->A0);
bound = tcg_constant_tl(ot == MO_64 ? 63 : 31);
zero = tcg_constant_tl(0);
tcg_gen_movcond_tl(TCG_COND_LEU, s->T0, s->A0, bound, s->T0, zero); tcg_gen_movcond_tl(TCG_COND_LEU, s->T0, s->A0, bound, s->T0, zero);
/* /*
* Extract the LEN into a mask. Lengths larger than * Extract the LEN into an inverse mask. Lengths larger than
* operand size get all ones. * operand size get all zeros, length 0 gets all ones.
*/ */
tcg_gen_extract_tl(s->A0, s->T1, 8, 8); tcg_gen_extract_tl(s->A0, s->T1, 8, 8);
tcg_gen_movcond_tl(TCG_COND_LEU, s->A0, s->A0, bound, s->A0, bound); tcg_gen_shl_tl(s->T1, mone, s->A0);
tcg_gen_movcond_tl(TCG_COND_LEU, s->T1, s->A0, bound, s->T1, zero);
tcg_gen_movi_tl(s->T1, 1); tcg_gen_andc_tl(s->T0, s->T0, s->T1);
tcg_gen_shl_tl(s->T1, s->T1, s->A0);
tcg_gen_subi_tl(s->T1, s->T1, 1);
tcg_gen_and_tl(s->T0, s->T0, s->T1);
gen_op_update1_cc(s); gen_op_update1_cc(s);
set_cc_op(s, CC_OP_LOGICB + ot); set_cc_op(s, CC_OP_LOGICB + ot);

12
tests/tcg/i386/test-i386-bmi2.c
View File

@ -99,6 +99,9 @@ int main(int argc, char *argv[]) {
result = bextrq(mask, 0x10f8); result = bextrq(mask, 0x10f8);
assert(result == 0); assert(result == 0);
result = bextrq(0xfedcba9876543210ull, 0x7f00);
assert(result == 0xfedcba9876543210ull);
result = blsiq(0x30); result = blsiq(0x30);
assert(result == 0x10); assert(result == 0x10);
@ -164,6 +167,15 @@ int main(int argc, char *argv[]) {
result = bextrl(mask, 0x1038); result = bextrl(mask, 0x1038);
assert(result == 0); assert(result == 0);
result = bextrl((reg_t)0x8f635a775ad3b9b4ull, 0x3018);
assert(result == 0x5a);
result = bextrl((reg_t)0xfedcba9876543210ull, 0x7f00);
assert(result == 0x76543210u);
result = bextrl(-1, 0);
assert(result == 0);
result = blsil(0xffff); result = blsil(0xffff);
assert(result == 1); assert(result == 1);