[Qemu-devel] [PATCH 11/11] target-m68k: Inline addx, subx, negx

[Richard Henderson <rth@twiddle.net>]

Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 target-m68k/helper.c    | 40 -----------------------------
 target-m68k/helper.h    |  2 --
 target-m68k/translate.c | 67 +++++++++++++++++++++++++++++++++++++++++--------
 3 files changed, 56 insertions(+), 53 deletions(-)

diff --git a/target-m68k/helper.c b/target-m68k/helper.c
index 6bd80a5..519eef3 100644
--- a/target-m68k/helper.c
+++ b/target-m68k/helper.c
@@ -275,46 +275,6 @@ uint32_t HELPER(sats)(uint32_t val, uint32_t v)
     return val;
 }
 
-uint32_t HELPER(subx_cc)(CPUM68KState *env, uint32_t op1, uint32_t op2)
-{
-    uint32_t res, new_x;
-
-    if (env->cc_x) {
-        new_x = (op1 <= op2);
-        res = op1 - (op2 + 1);
-    } else {
-        new_x = (op1 < op2);
-        res = op1 - op2;
-    }
-    env->cc_x = new_x;
-    env->cc_c = new_x;
-    env->cc_n = res;
-    env->cc_z |= res; /* !Z is sticky */
-    env->cc_v = (res ^ op1) & (op1 ^ op2);
-
-    return res;
-}
-
-uint32_t HELPER(addx_cc)(CPUM68KState *env, uint32_t op1, uint32_t op2)
-{
-    uint32_t res, new_x;
-
-    if (env->cc_x) {
-        res = op1 + op2 + 1;
-        new_x = (res <= op2);
-    } else {
-        res = op1 + op2;
-        new_x = (res < op2);
-    }
-    env->cc_x = new_x;
-    env->cc_c = new_x;
-    env->cc_n = res;
-    env->cc_z |= res; /* !Z is sticky.  */
-    env->cc_v = (res ^ op1) & ~(op1 ^ op2);
-
-    return res;
-}
-
 void HELPER(set_sr)(CPUM68KState *env, uint32_t val)
 {
     env->sr = val & 0xffe0;
diff --git a/target-m68k/helper.h b/target-m68k/helper.h
index 9985f9b..aae01f9 100644
--- a/target-m68k/helper.h
+++ b/target-m68k/helper.h
@@ -3,8 +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(addx_cc, i32, env, i32, i32)
-DEF_HELPER_3(subx_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 a536054..33d6747 100644
--- a/target-m68k/translate.c
+++ b/target-m68k/translate.c
@@ -1527,11 +1527,27 @@ DISAS_INSN(move)
 
 DISAS_INSN(negx)
 {
-    TCGv reg;
+    TCGv reg, z;
 
-    gen_flush_flags(s);
     reg = DREG(insn, 0);
-    gen_helper_subx_cc(reg, cpu_env, tcg_const_i32(0), reg);
+
+    /* Perform subtraction with borrow.  */
+    z = tcg_const_i32(0);
+    tcg_gen_add2_i32(QREG_CC_N, QREG_CC_X, reg, z, QREG_CC_X, z);
+    tcg_gen_sub2_i32(QREG_CC_N, QREG_CC_X, z, z, QREG_CC_N, QREG_CC_X);
+    tcg_temp_free(z);
+    tcg_gen_andi_i32(QREG_CC_X, QREG_CC_X, 1);
+
+    /* Compute signed-overflow for negation.  The normal formula for
+       subtraction is (res ^ src1) & (src1 ^ src2), but with src1==0
+       this simplies to res & src2.  */
+    tcg_gen_and_i32(QREG_CC_V, QREG_CC_N, reg);
+
+    /* Copy the rest of the results into place.  */
+    tcg_gen_mov_i32(QREG_CC_Z, QREG_CC_N);
+    tcg_gen_mov_i32(QREG_CC_C, QREG_CC_X);
+    tcg_gen_mov_i32(reg, QREG_CC_N);
+    set_cc_op(s, CC_OP_FLAGS);
 }
 
 DISAS_INSN(lea)
@@ -1951,13 +1967,28 @@ DISAS_INSN(suba)
 
 DISAS_INSN(subx)
 {
-    TCGv reg;
-    TCGv src;
+    TCGv reg, src, z;
 
-    gen_flush_flags(s);
     reg = DREG(insn, 9);
     src = DREG(insn, 0);
-    gen_helper_subx_cc(reg, cpu_env, reg, src);
+
+    /* Perform subtract with borrow.  */
+    z = tcg_const_i32(0);
+    tcg_gen_add2_i32(QREG_CC_N, QREG_CC_X, src, z, QREG_CC_X, z);
+    tcg_gen_sub2_i32(QREG_CC_N, QREG_CC_X, reg, z, QREG_CC_N, QREG_CC_X);
+    tcg_temp_free(z);
+    tcg_gen_andi_i32(QREG_CC_X, QREG_CC_X, 1);
+
+    /* Compute signed-overflow for subtraction.  */
+    tcg_gen_xor_i32(QREG_CC_V, QREG_CC_N, reg);
+    tcg_gen_xor_i32(QREG_CC_Z, reg, src);
+    tcg_gen_and_i32(QREG_CC_V, QREG_CC_V, QREG_CC_Z);
+
+    /* Copy the rest of the results into place.  */
+    tcg_gen_mov_i32(QREG_CC_Z, QREG_CC_N);
+    tcg_gen_mov_i32(QREG_CC_C, QREG_CC_X);
+    tcg_gen_mov_i32(reg, QREG_CC_N);
+    set_cc_op(s, CC_OP_FLAGS);
 }
 
 DISAS_INSN(mov3q)
@@ -2051,13 +2082,27 @@ DISAS_INSN(adda)
 
 DISAS_INSN(addx)
 {
-    TCGv reg;
-    TCGv src;
+    TCGv reg, src, z;
 
-    gen_flush_flags(s);
     reg = DREG(insn, 9);
     src = DREG(insn, 0);
-    gen_helper_addx_cc(reg, cpu_env, reg, src);
+
+    /* Perform addition with carry.  */
+    z = tcg_const_i32(0);
+    tcg_gen_add2_i32(QREG_CC_N, QREG_CC_X, QREG_CC_X, z, reg, z);
+    tcg_gen_add2_i32(QREG_CC_N, QREG_CC_X, QREG_CC_N, QREG_CC_X, src, z);
+    tcg_temp_free(z);
+
+    /* Compute signed-overflow for addition.  */
+    tcg_gen_xor_i32(QREG_CC_V, QREG_CC_N, reg);
+    tcg_gen_xor_i32(QREG_CC_Z, reg, src);
+    tcg_gen_andc_i32(QREG_CC_V, QREG_CC_V, QREG_CC_Z);
+
+    /* Copy the rest of the results into place.  */
+    tcg_gen_mov_i32(QREG_CC_Z, QREG_CC_N);
+    tcg_gen_mov_i32(QREG_CC_C, QREG_CC_X);
+    tcg_gen_mov_i32(reg, QREG_CC_N);
+    set_cc_op(s, CC_OP_FLAGS);
 }
 
 DISAS_INSN(shift_im)
-- 
2.4.3