[Qemu-devel] [PATCH v2 0/3] 680x0 instruction set, part 2

[Qemu-devel] [PATCH v2 0/3] 680x0 instruction set, part 2

[Laurent Vivier]

This series is another subset of the series I sent in May:
https://lists.gnu.org/archive/html/qemu-devel/2016-05/msg00501.html

It must be applied on top of series:
"target-m68k: 680x0 instruction set, part 1"

This subset contains reworked patches for:
- cmpm, delay the writeback of the value of the register
  after the second load to avoid problem with page fault,
- shift instruction, compute V flags as advised by Richard

I've checked it doesn't break coldfire support:
http://wiki.qemu.org/download/coldfire-test-0.1.tar.bz2
but it can't boot a 680x0 processor kernel.

v2:
- don't modify gen_extend() prototype
- use one "sari" instead of two "shri"s
- use "movi 0" to set QREG_CC_V to zero

Laurent Vivier (2):
  target-m68k: add cmpm
  target-m68k: shift ops manage word and byte operands

Richard Henderson (1):
  target-m68k: Inline shifts

 target-m68k/helper.c    |  52 ----------
 target-m68k/helper.h    |   3 -
 target-m68k/translate.c | 255 +++++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 229 insertions(+), 81 deletions(-)

-- 
2.7.4

[Qemu-devel] [PATCH v2 1/3] target-m68k: add cmpm

[Laurent Vivier]

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <rth@twiddle.net>
---
 target-m68k/translate.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/target-m68k/translate.c b/target-m68k/translate.c
index ee0ffe3..92e67eb 100644
--- a/target-m68k/translate.c
+++ b/target-m68k/translate.c
@@ -2173,6 +2173,33 @@ DISAS_INSN(cmpa)
     gen_update_cc_cmp(s, reg, src, opsize);
 }
 
+DISAS_INSN(cmpm)
+{
+    int opsize = insn_opsize(insn);
+    TCGv tmp = tcg_temp_new();
+    TCGv src, dst, addr;
+
+    src = gen_load(s, opsize, AREG(insn, 0), 1);
+    /* delay the update after the second gen_load() */
+    tcg_gen_addi_i32(tmp, AREG(insn, 0), opsize_bytes(opsize));
+
+    /* but if the we use the same address register to
+     * read the second value, we must use the updated address
+     */
+    if (REG(insn, 0) == REG(insn, 9)) {
+        addr = tmp;
+    } else {
+        addr = AREG(insn, 9);
+    }
+
+    dst = gen_load(s, opsize, addr, 1);
+    tcg_gen_mov_i32(AREG(insn, 0), tmp);
+    tcg_gen_addi_i32(AREG(insn, 9), addr, opsize_bytes(opsize));
+    tcg_temp_free(tmp);
+
+    gen_update_cc_cmp(s, dst, src, opsize);
+}
+
 DISAS_INSN(eor)
 {
     TCGv src;
@@ -3414,6 +3441,7 @@ void register_m68k_insns (CPUM68KState *env)
     INSN(cmpa,      b1c0, f1c0, CF_ISA_A);
     INSN(cmp,       b000, f100, M68000);
     INSN(eor,       b100, f100, M68000);
+    INSN(cmpm,      b108, f138, M68000);
     INSN(cmpa,      b0c0, f0c0, M68000);
     INSN(eor,       b180, f1c0, CF_ISA_A);
     BASE(and,       c000, f000);
-- 
2.7.4

[Qemu-devel] [PATCH v2 2/3] target-m68k: Inline shifts

[Laurent Vivier]

From: Richard Henderson <rth@twiddle.net>

Original patch from Richard Henderson <rth@twiddle.net>

Fix arithmetical/logical switch

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 target-m68k/helper.c    | 52 ---------------------------
 target-m68k/helper.h    |  3 --
 target-m68k/translate.c | 94 +++++++++++++++++++++++++++++++++++++------------
 3 files changed, 72 insertions(+), 77 deletions(-)

diff --git a/target-m68k/helper.c b/target-m68k/helper.c
index 7aed9ff..f750d3d 100644
--- a/target-m68k/helper.c
+++ b/target-m68k/helper.c
@@ -284,58 +284,6 @@ void HELPER(set_sr)(CPUM68KState *env, uint32_t val)
     m68k_switch_sp(env);
 }
 
-uint32_t HELPER(shl_cc)(CPUM68KState *env, uint32_t val, uint32_t shift)
-{
-    uint64_t result;
-
-    shift &= 63;
-    result = (uint64_t)val << shift;
-
-    env->cc_c = (result >> 32) & 1;
-    env->cc_n = result;
-    env->cc_z = result;
-    env->cc_v = 0;
-    env->cc_x = shift ? env->cc_c : env->cc_x;
-
-    return result;
-}
-
-uint32_t HELPER(shr_cc)(CPUM68KState *env, uint32_t val, uint32_t shift)
-{
-    uint64_t temp;
-    uint32_t result;
-
-    shift &= 63;
-    temp = (uint64_t)val << 32 >> shift;
-    result = temp >> 32;
-
-    env->cc_c = (temp >> 31) & 1;
-    env->cc_n = result;
-    env->cc_z = result;
-    env->cc_v = 0;
-    env->cc_x = shift ? env->cc_c : env->cc_x;
-
-    return result;
-}
-
-uint32_t HELPER(sar_cc)(CPUM68KState *env, uint32_t val, uint32_t shift)
-{
-    uint64_t temp;
-    uint32_t result;
-
-    shift &= 63;
-    temp = (int64_t)val << 32 >> shift;
-    result = temp >> 32;
-
-    env->cc_c = (temp >> 31) & 1;
-    env->cc_n = result;
-    env->cc_z = result;
-    env->cc_v = result ^ val;
-    env->cc_x = shift ? env->cc_c : env->cc_x;
-
-    return result;
-}
-
 /* FPU helpers.  */
 uint32_t HELPER(f64_to_i32)(CPUM68KState *env, float64 val)
 {
diff --git a/target-m68k/helper.h b/target-m68k/helper.h
index 2697e32..aae01f9 100644
--- a/target-m68k/helper.h
+++ b/target-m68k/helper.h
@@ -3,9 +3,6 @@ DEF_HELPER_1(ff1, i32, i32)
 DEF_HELPER_FLAGS_2(sats, TCG_CALL_NO_RWG_SE, i32, i32, i32)
 DEF_HELPER_2(divu, void, env, i32)
 DEF_HELPER_2(divs, void, env, i32)
-DEF_HELPER_3(shl_cc, i32, env, i32, i32)
-DEF_HELPER_3(shr_cc, i32, env, i32, i32)
-DEF_HELPER_3(sar_cc, i32, env, i32, i32)
 DEF_HELPER_2(set_sr, void, env, i32)
 DEF_HELPER_3(movec, void, env, i32, i32)
 
diff --git a/target-m68k/translate.c b/target-m68k/translate.c
index 92e67eb..461d756 100644
--- a/target-m68k/translate.c
+++ b/target-m68k/translate.c
@@ -2348,48 +2348,98 @@ DISAS_INSN(addx_mem)
     gen_store(s, opsize, addr_dest, QREG_CC_N);
 }
 
-/* TODO: This could be implemented without helper functions.  */
 DISAS_INSN(shift_im)
 {
-    TCGv reg;
-    int tmp;
-    TCGv shift;
+    TCGv reg = DREG(insn, 0);
+    int count = (insn >> 9) & 7;
+    int logical = insn & 8;
 
-    set_cc_op(s, CC_OP_FLAGS);
+    if (count == 0) {
+        count = 8;
+    }
 
-    reg = DREG(insn, 0);
-    tmp = (insn >> 9) & 7;
-    if (tmp == 0)
-        tmp = 8;
-    shift = tcg_const_i32(tmp);
-    /* No need to flush flags becuse we know we will set C flag.  */
     if (insn & 0x100) {
-        gen_helper_shl_cc(reg, cpu_env, reg, shift);
+        tcg_gen_shri_i32(QREG_CC_C, reg, 31 - count);
+        tcg_gen_shli_i32(QREG_CC_N, reg, count);
     } else {
-        if (insn & 8) {
-            gen_helper_shr_cc(reg, cpu_env, reg, shift);
+        tcg_gen_shri_i32(QREG_CC_C, reg, count - 1);
+        if (logical) {
+            tcg_gen_shri_i32(QREG_CC_N, reg, count);
         } else {
-            gen_helper_sar_cc(reg, cpu_env, reg, shift);
+            tcg_gen_sari_i32(QREG_CC_N, reg, count);
         }
     }
+    tcg_gen_andi_i32(QREG_CC_C, QREG_CC_C, 1);
+    tcg_gen_mov_i32(QREG_CC_Z, QREG_CC_N);
+    tcg_gen_mov_i32(QREG_CC_X, QREG_CC_C);
+
+    /* Note that ColdFire always clears V, while M68000 sets it for
+       a change in the sign bit.  */
+    if (!logical && m68k_feature(s->env, M68K_FEATURE_M68000)) {
+        tcg_gen_xor_i32(QREG_CC_V, QREG_CC_N, reg);
+    } else {
+        tcg_gen_movi_i32(QREG_CC_V, 0);
+    }
+
+    tcg_gen_mov_i32(reg, QREG_CC_N);
+    set_cc_op(s, CC_OP_FLAGS);
 }
 
 DISAS_INSN(shift_reg)
 {
-    TCGv reg;
-    TCGv shift;
+    TCGv reg, s32;
+    TCGv_i64 t64, s64;
+    int logical = insn & 8;
 
     reg = DREG(insn, 0);
-    shift = DREG(insn, 9);
+    t64 = tcg_temp_new_i64();
+    s64 = tcg_temp_new_i64();
+    s32 = tcg_temp_new();
+
+    /* Note that m68k truncates the shift count modulo 64, not 32.
+       In addition, a 64-bit shift makes it easy to find "the last
+       bit shifted out", for the carry flag.  */
+    tcg_gen_andi_i32(s32, DREG(insn, 9), 63);
+    tcg_gen_extu_i32_i64(s64, s32);
+
+    /* Non-arithmetic shift clears V.  Use it as a source zero here.  */
+    tcg_gen_movi_i32(QREG_CC_V, 0);
+
     if (insn & 0x100) {
-        gen_helper_shl_cc(reg, cpu_env, reg, shift);
+        tcg_gen_extu_i32_i64(t64, reg);
+        tcg_gen_shl_i64(t64, t64, s64);
+        tcg_temp_free_i64(s64);
+        tcg_gen_extr_i64_i32(QREG_CC_N, QREG_CC_C, t64);
+        tcg_temp_free_i64(t64);
+        tcg_gen_andi_i32(QREG_CC_C, QREG_CC_C, 1);
     } else {
-        if (insn & 8) {
-            gen_helper_shr_cc(reg, cpu_env, reg, shift);
+        tcg_gen_extu_i32_i64(t64, reg);
+        tcg_gen_shli_i64(t64, t64, 32);
+        if (logical) {
+            tcg_gen_shr_i64(t64, t64, s64);
         } else {
-            gen_helper_sar_cc(reg, cpu_env, reg, shift);
+            tcg_gen_sar_i64(t64, t64, s64);
         }
+        tcg_temp_free_i64(s64);
+        tcg_gen_extr_i64_i32(QREG_CC_C, QREG_CC_N, t64);
+        tcg_temp_free_i64(t64);
+        tcg_gen_shri_i32(QREG_CC_C, QREG_CC_C, 31);
     }
+    tcg_gen_mov_i32(QREG_CC_Z, QREG_CC_N);
+
+    /* Note that X = C, but only if the shift count was non-zero.  */
+    tcg_gen_movcond_i32(TCG_COND_NE, QREG_CC_X, s32, QREG_CC_V,
+                        QREG_CC_C, QREG_CC_X);
+    tcg_temp_free(s32);
+
+    /* Note that ColdFire always clears V (which we have done above),
+       while M68000 sets it for a change in the sign bit.  */
+    if (!logical && m68k_feature(s->env, M68K_FEATURE_M68000)) {
+        tcg_gen_xor_i32(QREG_CC_V, QREG_CC_N, reg);
+    }
+
+    /* Write back the result.  */
+    tcg_gen_mov_i32(reg, QREG_CC_N);
     set_cc_op(s, CC_OP_FLAGS);
 }
 
-- 
2.7.4

[Qemu-devel] [PATCH v2 3/3] target-m68k: shift ops manage word and byte operands

[Laurent Vivier]

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 target-m68k/translate.c | 187 ++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 156 insertions(+), 31 deletions(-)

diff --git a/target-m68k/translate.c b/target-m68k/translate.c
index 461d756..c00978d 100644
--- a/target-m68k/translate.c
+++ b/target-m68k/translate.c
@@ -2348,19 +2348,40 @@ DISAS_INSN(addx_mem)
     gen_store(s, opsize, addr_dest, QREG_CC_N);
 }
 
-DISAS_INSN(shift_im)
+static inline void shift_im(DisasContext *s, uint16_t insn, int opsize)
 {
-    TCGv reg = DREG(insn, 0);
     int count = (insn >> 9) & 7;
     int logical = insn & 8;
+    int left = insn & 0x100;
+    int bits = opsize_bytes(opsize) * 8;
+    TCGv reg = gen_extend(DREG(insn, 0), opsize, !logical);
 
     if (count == 0) {
         count = 8;
     }
 
-    if (insn & 0x100) {
-        tcg_gen_shri_i32(QREG_CC_C, reg, 31 - count);
+    tcg_gen_movi_i32(QREG_CC_V, 0);
+    if (left) {
+        tcg_gen_shri_i32(QREG_CC_C, reg, bits - count);
         tcg_gen_shli_i32(QREG_CC_N, reg, count);
+
+        /* Note that ColdFire always clears V,
+           while M68000 sets if the most significant bit is changed at
+           any time during the shift operation */
+        if (!logical && m68k_feature(s->env, M68K_FEATURE_M68000)) {
+            /* if shift count >= bits, V is (reg != 0) */
+            if (count >= bits) {
+                tcg_gen_setcond_i32(TCG_COND_NE, QREG_CC_V, reg, QREG_CC_V);
+            } else {
+                TCGv t0 = tcg_temp_new();
+                TCGv t1 = tcg_temp_new();
+                /* mask of sign bit */
+                tcg_gen_sari_i32(t0, reg, 31);
+                tcg_gen_sari_i32(t1, reg, bits - count);
+                tcg_gen_setcond_i32(TCG_COND_NE, QREG_CC_V, t0, t1);
+            }
+            tcg_gen_neg_i32(QREG_CC_V, QREG_CC_V);
+        }
     } else {
         tcg_gen_shri_i32(QREG_CC_C, reg, count - 1);
         if (logical) {
@@ -2369,29 +2390,26 @@ DISAS_INSN(shift_im)
             tcg_gen_sari_i32(QREG_CC_N, reg, count);
         }
     }
+
+    gen_ext(QREG_CC_N, QREG_CC_N, opsize, 1);
     tcg_gen_andi_i32(QREG_CC_C, QREG_CC_C, 1);
     tcg_gen_mov_i32(QREG_CC_Z, QREG_CC_N);
     tcg_gen_mov_i32(QREG_CC_X, QREG_CC_C);
 
-    /* Note that ColdFire always clears V, while M68000 sets it for
-       a change in the sign bit.  */
-    if (!logical && m68k_feature(s->env, M68K_FEATURE_M68000)) {
-        tcg_gen_xor_i32(QREG_CC_V, QREG_CC_N, reg);
-    } else {
-        tcg_gen_movi_i32(QREG_CC_V, 0);
-    }
-
-    tcg_gen_mov_i32(reg, QREG_CC_N);
+    gen_partset_reg(opsize, DREG(insn, 0), QREG_CC_N);
     set_cc_op(s, CC_OP_FLAGS);
 }
 
-DISAS_INSN(shift_reg)
+static inline void shift_reg(DisasContext *s, uint16_t insn, int opsize)
 {
-    TCGv reg, s32;
-    TCGv_i64 t64, s64;
     int logical = insn & 8;
+    int left = insn & 0x100;
+    int bits = opsize_bytes(opsize) * 8;
+    TCGv reg = gen_extend(DREG(insn, 0), opsize, !logical);
+    TCGv s32;
+    TCGv_i64 t64, s64;
+    TCGv zero;
 
-    reg = DREG(insn, 0);
     t64 = tcg_temp_new_i64();
     s64 = tcg_temp_new_i64();
     s32 = tcg_temp_new();
@@ -2402,44 +2420,144 @@ DISAS_INSN(shift_reg)
     tcg_gen_andi_i32(s32, DREG(insn, 9), 63);
     tcg_gen_extu_i32_i64(s64, s32);
 
-    /* Non-arithmetic shift clears V.  Use it as a source zero here.  */
-    tcg_gen_movi_i32(QREG_CC_V, 0);
+    zero = tcg_const_i32(0);
+    tcg_gen_mov_i32(QREG_CC_V, zero);
 
-    if (insn & 0x100) {
-        tcg_gen_extu_i32_i64(t64, reg);
+    tcg_gen_extu_i32_i64(t64, reg);
+    if (left) {
+        tcg_gen_shli_i64(t64, t64, 32 - bits);
         tcg_gen_shl_i64(t64, t64, s64);
         tcg_temp_free_i64(s64);
         tcg_gen_extr_i64_i32(QREG_CC_N, QREG_CC_C, t64);
         tcg_temp_free_i64(t64);
+        tcg_gen_sari_i32(QREG_CC_N, QREG_CC_N, 32 - bits);
         tcg_gen_andi_i32(QREG_CC_C, QREG_CC_C, 1);
+
+        /* Note that ColdFire always clears V,
+           while M68000 sets if the most significant bit is changed at
+           any time during the shift operation */
+        if (!logical && m68k_feature(s->env, M68K_FEATURE_M68000)) {
+            TCGv t0 = tcg_temp_new();
+            TCGv t1 = tcg_temp_new();
+            TCGv t2 = tcg_const_i32(bits);
+
+            tcg_gen_sub_i32(t2, t2, s32); /* t2 = bits - count */
+
+            tcg_gen_sari_i32(t0, reg, 31);
+            tcg_gen_sar_i32(t1, reg, t2);
+            tcg_temp_free(t2);
+            tcg_gen_setcond_i32(TCG_COND_NE, QREG_CC_V, t0, t1);
+            tcg_temp_free(t1);
+
+            /* if shift count >= bits, V is (reg != 0) */
+            tcg_gen_setcond_i32(TCG_COND_NE, t0, reg, zero);
+            tcg_gen_movcond_i32(TCG_COND_GE, QREG_CC_V, s32, t2, t0, QREG_CC_V);
+
+            tcg_temp_free(t0);
+
+            tcg_gen_neg_i32(QREG_CC_V, QREG_CC_V);
+
+            /* if shift count is zero, V is 0 */
+            tcg_gen_movcond_i32(TCG_COND_NE, QREG_CC_V, s32, zero,
+                                QREG_CC_V, zero);
+        }
     } else {
-        tcg_gen_extu_i32_i64(t64, reg);
-        tcg_gen_shli_i64(t64, t64, 32);
+        tcg_gen_shli_i64(t64, t64, 64 - bits);
         if (logical) {
+            tcg_gen_shri_i64(t64, t64, 32 - bits);
             tcg_gen_shr_i64(t64, t64, s64);
         } else {
+            tcg_gen_sari_i64(t64, t64, 32 - bits);
             tcg_gen_sar_i64(t64, t64, s64);
         }
         tcg_temp_free_i64(s64);
         tcg_gen_extr_i64_i32(QREG_CC_C, QREG_CC_N, t64);
         tcg_temp_free_i64(t64);
+        gen_ext(QREG_CC_N, QREG_CC_N, opsize, 1);
         tcg_gen_shri_i32(QREG_CC_C, QREG_CC_C, 31);
     }
     tcg_gen_mov_i32(QREG_CC_Z, QREG_CC_N);
 
-    /* Note that X = C, but only if the shift count was non-zero.  */
-    tcg_gen_movcond_i32(TCG_COND_NE, QREG_CC_X, s32, QREG_CC_V,
+    /* C is cleared if shift count was zero */
+    tcg_gen_movcond_i32(TCG_COND_NE, QREG_CC_C, s32, zero,
+                        QREG_CC_C, zero);
+
+    /* X = C, but only if the shift count was non-zero.  */
+    tcg_gen_movcond_i32(TCG_COND_NE, QREG_CC_X, s32, zero,
                         QREG_CC_C, QREG_CC_X);
+    tcg_temp_free(zero);
     tcg_temp_free(s32);
 
-    /* Note that ColdFire always clears V (which we have done above),
-       while M68000 sets it for a change in the sign bit.  */
-    if (!logical && m68k_feature(s->env, M68K_FEATURE_M68000)) {
-        tcg_gen_xor_i32(QREG_CC_V, QREG_CC_N, reg);
+    /* Write back the result.  */
+    gen_partset_reg(opsize, DREG(insn, 0), QREG_CC_N);
+    set_cc_op(s, CC_OP_FLAGS);
+}
+
+DISAS_INSN(shift8_im)
+{
+    shift_im(s, insn, OS_BYTE);
+}
+
+DISAS_INSN(shift16_im)
+{
+    shift_im(s, insn, OS_WORD);
+}
+
+DISAS_INSN(shift_im)
+{
+    shift_im(s, insn, OS_LONG);
+}
+
+DISAS_INSN(shift8_reg)
+{
+    shift_reg(s, insn, OS_BYTE);
+}
+
+DISAS_INSN(shift16_reg)
+{
+    shift_reg(s, insn, OS_WORD);
+}
+
+DISAS_INSN(shift_reg)
+{
+    shift_reg(s, insn, OS_LONG);
+}
+
+DISAS_INSN(shift_mem)
+{
+    int logical = insn & 8;
+    int left = insn & 0x100;
+    TCGv src;
+    TCGv addr;
+
+    SRC_EA(env, src, OS_WORD, !logical, &addr);
+    tcg_gen_movi_i32(QREG_CC_V, 0);
+    if (left) {
+        tcg_gen_shri_i32(QREG_CC_C, src, 15);
+        tcg_gen_shli_i32(QREG_CC_N, src, 1);
+
+        /* Note that ColdFire always clears V,
+           while M68000 sets if the most significant bit is changed at
+           any time during the shift operation */
+        if (!logical && m68k_feature(s->env, M68K_FEATURE_M68000)) {
+            src = gen_extend(src, OS_WORD, 1);
+            tcg_gen_xor_i32(QREG_CC_V, QREG_CC_N, src);
+        }
+    } else {
+        tcg_gen_mov_i32(QREG_CC_C, src);
+        if (logical) {
+            tcg_gen_shri_i32(QREG_CC_N, src, 1);
+        } else {
+            tcg_gen_sari_i32(QREG_CC_N, src, 1);
+        }
     }
 
-    /* Write back the result.  */
-    tcg_gen_mov_i32(reg, QREG_CC_N);
+    gen_ext(QREG_CC_N, QREG_CC_N, OS_WORD, 1);
+    tcg_gen_andi_i32(QREG_CC_C, QREG_CC_C, 1);
+    tcg_gen_mov_i32(QREG_CC_Z, QREG_CC_N);
+    tcg_gen_mov_i32(QREG_CC_X, QREG_CC_C);
+
+    DEST_EA(env, insn, OS_WORD, QREG_CC_N, &addr);
     set_cc_op(s, CC_OP_FLAGS);
 }
 
@@ -3508,6 +3626,13 @@ void register_m68k_insns (CPUM68KState *env)
     INSN(adda,      d0c0, f0c0, M68000);
     INSN(shift_im,  e080, f0f0, CF_ISA_A);
     INSN(shift_reg, e0a0, f0f0, CF_ISA_A);
+    INSN(shift8_im, e000, f0f0, M68000);
+    INSN(shift16_im, e040, f0f0, M68000);
+    INSN(shift_im,  e080, f0f0, M68000);
+    INSN(shift8_reg, e020, f0f0, M68000);
+    INSN(shift16_reg, e060, f0f0, M68000);
+    INSN(shift_reg, e0a0, f0f0, M68000);
+    INSN(shift_mem, e0c0, fcc0, M68000);
     INSN(undef_fpu, f000, f000, CF_ISA_A);
     INSN(fpu,       f200, ffc0, CF_FPU);
     INSN(fbcc,      f280, ffc0, CF_FPU);
-- 
2.7.4

Re: [Qemu-devel] [PATCH v2 3/3] target-m68k: shift ops manage word and byte operands

[Richard Henderson]

On 10/27/2016 02:43 PM, Laurent Vivier wrote:
> +static inline void shift_reg(DisasContext *s, uint16_t insn, int opsize)
>  {
> -    TCGv reg, s32;
> -    TCGv_i64 t64, s64;
>      int logical = insn & 8;
> +    int left = insn & 0x100;
> +    int bits = opsize_bytes(opsize) * 8;
> +    TCGv reg = gen_extend(DREG(insn, 0), opsize, !logical);
> +    TCGv s32;
> +    TCGv_i64 t64, s64;
> +    TCGv zero;
>
> -    reg = DREG(insn, 0);
>      t64 = tcg_temp_new_i64();
>      s64 = tcg_temp_new_i64();
>      s32 = tcg_temp_new();
> @@ -2402,44 +2420,144 @@ DISAS_INSN(shift_reg)
>      tcg_gen_andi_i32(s32, DREG(insn, 9), 63);
>      tcg_gen_extu_i32_i64(s64, s32);
>
> -    /* Non-arithmetic shift clears V.  Use it as a source zero here.  */
> -    tcg_gen_movi_i32(QREG_CC_V, 0);
> +    zero = tcg_const_i32(0);
> +    tcg_gen_mov_i32(QREG_CC_V, zero);
>
> -    if (insn & 0x100) {
> -        tcg_gen_extu_i32_i64(t64, reg);
> +    tcg_gen_extu_i32_i64(t64, reg);
> +    if (left) {
> +        tcg_gen_shli_i64(t64, t64, 32 - bits);
>          tcg_gen_shl_i64(t64, t64, s64);
>          tcg_temp_free_i64(s64);
>          tcg_gen_extr_i64_i32(QREG_CC_N, QREG_CC_C, t64);
>          tcg_temp_free_i64(t64);
> +        tcg_gen_sari_i32(QREG_CC_N, QREG_CC_N, 32 - bits);
>          tcg_gen_andi_i32(QREG_CC_C, QREG_CC_C, 1);
> +
> +        /* Note that ColdFire always clears V,
> +           while M68000 sets if the most significant bit is changed at
> +           any time during the shift operation */
> +        if (!logical && m68k_feature(s->env, M68K_FEATURE_M68000)) {
> +            TCGv t0 = tcg_temp_new();
> +            TCGv t1 = tcg_temp_new();
> +            TCGv t2 = tcg_const_i32(bits);
> +
> +            tcg_gen_sub_i32(t2, t2, s32); /* t2 = bits - count */
> +
> +            tcg_gen_sari_i32(t0, reg, 31);
> +            tcg_gen_sar_i32(t1, reg, t2);
> +            tcg_temp_free(t2);
> +            tcg_gen_setcond_i32(TCG_COND_NE, QREG_CC_V, t0, t1);
> +            tcg_temp_free(t1);
> +
> +            /* if shift count >= bits, V is (reg != 0) */
> +            tcg_gen_setcond_i32(TCG_COND_NE, t0, reg, zero);
> +            tcg_gen_movcond_i32(TCG_COND_GE, QREG_CC_V, s32, t2, t0, QREG_CC_V);
> +
> +            tcg_temp_free(t0);
> +
> +            tcg_gen_neg_i32(QREG_CC_V, QREG_CC_V);
> +
> +            /* if shift count is zero, V is 0 */
> +            tcg_gen_movcond_i32(TCG_COND_NE, QREG_CC_V, s32, zero,
> +                                QREG_CC_V, zero);

This computation is not quite right, in that you compute bits - count and don't 
bound that against 0..31 for the sar_i32.

I think we can also to better for the two things you're special-casing: count 
 >= bits and count == 0.  I need to think about that some more.


r~

Re: [Qemu-devel] [PATCH v2 1/3] target-m68k: add cmpm

[Richard Henderson]

On 10/27/2016 03:43 PM, Laurent Vivier wrote:
> +DISAS_INSN(cmpm)
> +{
> +    int opsize = insn_opsize(insn);
> +    TCGv tmp = tcg_temp_new();
> +    TCGv src, dst, addr;
> +
> +    src = gen_load(s, opsize, AREG(insn, 0), 1);
> +    /* delay the update after the second gen_load() */
> +    tcg_gen_addi_i32(tmp, AREG(insn, 0), opsize_bytes(opsize));
> +
> +    /* but if the we use the same address register to
> +     * read the second value, we must use the updated address
> +     */
> +    if (REG(insn, 0) == REG(insn, 9)) {
> +        addr = tmp;
> +    } else {
> +        addr = AREG(insn, 9);
> +    }
> +
> +    dst = gen_load(s, opsize, addr, 1);
> +    tcg_gen_mov_i32(AREG(insn, 0), tmp);
> +    tcg_gen_addi_i32(AREG(insn, 9), addr, opsize_bytes(opsize));

I wonder if we should make this more generic.
I'm thinking of transparently fixing

     case 3: /* Indirect postincrement.  */
         reg = AREG(insn, 0);
         result = gen_ldst(s, opsize, reg, val, what);
         /* ??? This is not exception safe.  The instruction may still
            fault after this point.  */
         if (what == EA_STORE || !addrp)
             tcg_gen_addi_i32(reg, reg, opsize_bytes(opsize));
         return result;

If we add to DisasContext

	unsigned writeback_mask;
	TCGv writeback[8];

Then

static TCGv get_areg(DisasContext *s, unsigned regno)
{
     if (s->writeback_mask & (1 << regno)) {
         return s->writeback[regno];
     } else {
         return cpu_aregs[regno];
     }
}

static void delay_set_areg(DisasContext *s, unsigned regno,
                            TCGv val, bool give_temp)
{
     if (s->writeback_mask & (1 << regno)) {
         tcg_gen_mov_i32(s->writeback[regno], val);
         if (give_temp) {
             tcg_temp_free(val);
         }
     } else {
         s->writeback_mask |= 1 << regno;
         if (give_temp) {
             s->writeback[regno] = val;
         } else {
             TCGv tmp = tcg_temp_new();
             tcg_gen_mov_i32(tmp, val);
             s->writeback[regno] = tmp;
         }
     }
}

static void do_writebacks(DisasContext *s)
{
     unsigned mask = s->writeback_mask;
     if (mask) {
         s->writeback_mask = 0;
         do {
             unsigned regno = ctz32(mask);
             tcg_gen_mov_i32(cpu_aregs[regno], s->writeback[regno]);
             tcg_temp_free(s->writeback[regno]);
             mask &= mask - 1;
         } while (mask);
     }
}

where get_areg is used within the AREG macro, delay_set_areg is used in those 
cases where pre- and post-increment are needed, and do_writebacks is invoked at 
the end of disas_m68k_insn.

This all pre-supposes that cmpm is not a special-case within the ISA, that any 
time one reuses a register after modification one sees the new value.  Given 
the existing code within gen_ea, this would seem to be the case.

Thoughts?


r~

Re: [Qemu-devel] [PATCH v2 1/3] target-m68k: add cmpm

[Laurent Vivier]

Le 01/11/2016 à 18:48, Richard Henderson a écrit :
> On 10/27/2016 03:43 PM, Laurent Vivier wrote:
>> +DISAS_INSN(cmpm)
>> +{
>> +    int opsize = insn_opsize(insn);
>> +    TCGv tmp = tcg_temp_new();
>> +    TCGv src, dst, addr;
>> +
>> +    src = gen_load(s, opsize, AREG(insn, 0), 1);
>> +    /* delay the update after the second gen_load() */
>> +    tcg_gen_addi_i32(tmp, AREG(insn, 0), opsize_bytes(opsize));
>> +
>> +    /* but if the we use the same address register to
>> +     * read the second value, we must use the updated address
>> +     */
>> +    if (REG(insn, 0) == REG(insn, 9)) {
>> +        addr = tmp;
>> +    } else {
>> +        addr = AREG(insn, 9);
>> +    }
>> +
>> +    dst = gen_load(s, opsize, addr, 1);
>> +    tcg_gen_mov_i32(AREG(insn, 0), tmp);
>> +    tcg_gen_addi_i32(AREG(insn, 9), addr, opsize_bytes(opsize));
> 
> I wonder if we should make this more generic.
> I'm thinking of transparently fixing
> 
>     case 3: /* Indirect postincrement.  */
>         reg = AREG(insn, 0);
>         result = gen_ldst(s, opsize, reg, val, what);
>         /* ??? This is not exception safe.  The instruction may still
>            fault after this point.  */
>         if (what == EA_STORE || !addrp)
>             tcg_gen_addi_i32(reg, reg, opsize_bytes(opsize));
>         return result;
> 
> If we add to DisasContext
> 
>     unsigned writeback_mask;
>     TCGv writeback[8];
> 
> Then
> 
> static TCGv get_areg(DisasContext *s, unsigned regno)
> {
>     if (s->writeback_mask & (1 << regno)) {
>         return s->writeback[regno];
>     } else {
>         return cpu_aregs[regno];
>     }
> }
> 
> static void delay_set_areg(DisasContext *s, unsigned regno,
>                            TCGv val, bool give_temp)
> {
>     if (s->writeback_mask & (1 << regno)) {
>         tcg_gen_mov_i32(s->writeback[regno], val);
>         if (give_temp) {
>             tcg_temp_free(val);
>         }
>     } else {
>         s->writeback_mask |= 1 << regno;
>         if (give_temp) {
>             s->writeback[regno] = val;
>         } else {
>             TCGv tmp = tcg_temp_new();
>             tcg_gen_mov_i32(tmp, val);
>             s->writeback[regno] = tmp;
>         }
>     }
> }
> 
> static void do_writebacks(DisasContext *s)
> {
>     unsigned mask = s->writeback_mask;
>     if (mask) {
>         s->writeback_mask = 0;
>         do {
>             unsigned regno = ctz32(mask);
>             tcg_gen_mov_i32(cpu_aregs[regno], s->writeback[regno]);
>             tcg_temp_free(s->writeback[regno]);
>             mask &= mask - 1;
>         } while (mask);
>     }
> }
> 
> where get_areg is used within the AREG macro, delay_set_areg is used in
> those cases where pre- and post-increment are needed, and do_writebacks
> is invoked at the end of disas_m68k_insn.
> 
> This all pre-supposes that cmpm is not a special-case within the ISA,
> that any time one reuses a register after modification one sees the new
> value.  Given the existing code within gen_ea, this would seem to be the
> case.
> 
> Thoughts?

I think it's really a good idea to manage this in a generic way.
As you have already written 90% of the code, do you want to provide a
patch? I can test this with coldfire kernel and 68020 linux-user container.

Thanks,
Laurent