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target/arm: Convert CLZ

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Document our choice about the T32 CONSTRAINED UNPREDICTABLE behaviour.
This matches the undocumented choice made by the legacy decoder.

Backports commit 4c97f5b2f0fa9b37f9ff497f15411d809e6fd098 from qemu
This commit is contained in:
Richard Henderson 2019-11-19 20:14:35 -05:00 committed by Lioncash
parent 94968602b8
commit 74040da34c
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GPG key ID: 4E3C3CC1031BA9C7
3 changed files with 26 additions and 17 deletions
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4
qemu/target/arm/a32.decode
View file

@ -29,6 +29,7 @@
&s_rrrr s rd rn rm ra
&rrrr rd rn rm ra
&rrr rd rn rm
&rr rd rm
&r rm
&msr_reg rn r mask
&mrs_reg rd r
@ -197,6 +198,7 @@ CRC32CW .... 0001 0100 .... .... 0010 0100 .... @rndm
%sysm 8:1 16:4
@rm ---- .... .... .... .... .... .... rm:4 &r
@rdm ---- .... .... .... rd:4 .... .... rm:4 &rr
MRS_bank ---- 0001 0 r:1 00 .... rd:4 001. 0000 0000 &mrs_bank %sysm
MSR_bank ---- 0001 0 r:1 10 .... 1111 001. 0000 rn:4 &msr_bank %sysm
@ -207,3 +209,5 @@ MSR_reg ---- 0001 0 r:1 10 mask:4 1111 0000 0000 rn:4 &msr_reg
BX .... 0001 0010 1111 1111 1111 0001 .... @rm
BXJ .... 0001 0010 1111 1111 1111 0010 .... @rm
BLX_r .... 0001 0010 1111 1111 1111 0011 .... @rm
CLZ .... 0001 0110 1111 .... 1111 0001 .... @rdm

7
qemu/target/arm/t32.decode
View file

@ -26,6 +26,7 @@
&s_rrrr !extern s rd rn rm ra
&rrrr !extern rd rn rm ra
&rrr !extern rd rn rm
&rr !extern rd rm
&r !extern rm
&msr_reg !extern rn r mask
&mrs_reg !extern rd r
@ -124,8 +125,9 @@ RSB_rri 1111 0.0 1110 . .... 0 ... .... ........ @s_rri_rot
@s0_rnadm .... .... .... rn:4 ra:4 rd:4 .... rm:4 &s_rrrr s=0
@s0_rn0dm .... .... .... rn:4 .... rd:4 .... rm:4 &s_rrrr ra=0 s=0
@rnadm .... .... .... rn:4 ra:4 rd:4 .... rm:4 &rrrr
@rndm .... .... .... rn:4 .... rd:4 .... rm:4 &rrr
@rn0dm .... .... .... rn:4 .... rd:4 .... rm:4 &rrrr ra=0
@rndm .... .... .... rn:4 .... rd:4 .... rm:4 &rrr
@rdm .... .... .... .... .... rd:4 .... rm:4 &rr
{
MUL 1111 1011 0000 .... 1111 .... 0000 .... @s0_rn0dm
@ -180,6 +182,9 @@ CRC32CB 1111 1010 1101 .... 1111 .... 1000 .... @rndm
CRC32CH 1111 1010 1101 .... 1111 .... 1001 .... @rndm
CRC32CW 1111 1010 1101 .... 1111 .... 1010 .... @rndm
# Note rn != rm is CONSTRAINED UNPREDICTABLE; we choose to ignore rn.
CLZ 1111 1010 1011 ---- 1111 .... 1000 .... @rdm
# Branches and miscellaneous control
%msr_sysm 4:1 8:4

32
qemu/target/arm/translate.c
View file

@ -8717,6 +8717,20 @@ static bool trans_BLX_r(DisasContext *s, arg_BLX_r *a)
return true;
}
static bool trans_CLZ(DisasContext *s, arg_CLZ *a)
{
TCGContext *tcg_ctx = s->uc->tcg_ctx;
TCGv_i32 tmp;
if (!ENABLE_ARCH_5) {
return false;
}
tmp = load_reg(s, a->rm);
tcg_gen_clzi_i32(tcg_ctx, tmp, tmp, 32);
store_reg(s, a->rd, tmp);
return true;
}
/*
* Legacy decoder.
*/
@ -9014,18 +9028,7 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn)
/* MSR/MRS (banked/register) */
/* All done in decodetree. Illegal ops already signalled. */
g_assert_not_reached();
case 0x1:
if (op1 == 3) {
/* clz */
ARCH(5);
rd = (insn >> 12) & 0xf;
tmp = load_reg(s, rm);
tcg_gen_clzi_i32(tcg_ctx, tmp, tmp, 32);
store_reg(s, rd, tmp);
} else {
goto illegal_op;
}
break;
case 0x1: /* bx, clz */
case 0x2: /* bxj */
case 0x3: /* blx */
case 0x4: /* crc32 */
@ -10470,13 +10473,13 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
case 0x08: /* rev */
case 0x09: /* rev16 */
case 0x0b: /* revsh */
case 0x18: /* clz */
break;
case 0x10: /* sel */
if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
goto illegal_op;
}
break;
case 0x18: /* clz, in decodetree */
case 0x20: /* crc32/crc32c, in decodetree */
case 0x21:
case 0x22:
@ -10509,9 +10512,6 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
tcg_temp_free_i32(tcg_ctx, tmp3);
tcg_temp_free_i32(tcg_ctx, tmp2);
break;
case 0x18: /* clz */
tcg_gen_clzi_i32(tcg_ctx, tmp, tmp, 32);
break;
default:
g_assert_not_reached();
}