tcg: Add TCG_COND_NEVER, TCG_COND_ALWAYS

There are several cases that can be handled easier inside both
translators and code generators if we have out-of-band values
for conditions.  It's easy enough to handle ALWAYS and NEVER in
the natural way inside the tcg middle-end.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

tcg/arm/tcg-target.c

@@ -335,7 +335,7 @@ enum arm_cond_code_e {
     COND_AL = 0xe,
 };
 
-static const uint8_t tcg_cond_to_arm_cond[10] = {
+static const uint8_t tcg_cond_to_arm_cond[] = {
     [TCG_COND_EQ] = COND_EQ,
     [TCG_COND_NE] = COND_NE,
     [TCG_COND_LT] = COND_LT,

tcg/hppa/tcg-target.c

@@ -732,7 +732,7 @@ static void tcg_out_branch(TCGContext *s, int label_index, int nul)
     }
 }
 
-static const uint8_t tcg_cond_to_cmp_cond[10] =
+static const uint8_t tcg_cond_to_cmp_cond[] =
 {
     [TCG_COND_EQ] = COND_EQ,
     [TCG_COND_NE] = COND_EQ | COND_FALSE,

tcg/i386/tcg-target.c

@@ -338,7 +338,7 @@ static inline int tcg_target_const_match(tcg_target_long val,
 #define JCC_JLE 0xe
 #define JCC_JG  0xf
 
-static const uint8_t tcg_cond_to_jcc[10] = {
+static const uint8_t tcg_cond_to_jcc[] = {
     [TCG_COND_EQ] = JCC_JE,
     [TCG_COND_NE] = JCC_JNE,
     [TCG_COND_LT] = JCC_JL,

tcg/optimize.c

@@ -321,6 +321,8 @@ static TCGArg do_constant_folding_cond(TCGOpcode op, TCGArg x,
                 return (uint32_t)temps[x].val <= (uint32_t)temps[y].val;
             case TCG_COND_GTU:
                 return (uint32_t)temps[x].val > (uint32_t)temps[y].val;
+            default:
+                break;
             }
             break;
         case 64:
@@ -345,6 +347,8 @@ static TCGArg do_constant_folding_cond(TCGOpcode op, TCGArg x,
                 return (uint64_t)temps[x].val <= (uint64_t)temps[y].val;
             case TCG_COND_GTU:
                 return (uint64_t)temps[x].val > (uint64_t)temps[y].val;
+            default:
+                break;
             }
             break;
         }
@@ -362,6 +366,8 @@ static TCGArg do_constant_folding_cond(TCGOpcode op, TCGArg x,
         case TCG_COND_LEU:
         case TCG_COND_EQ:
             return 1;
+        default:
+            break;
         }
     } else if (temps[y].state == TCG_TEMP_CONST && temps[y].val == 0) {
         switch (c) {

tcg/ppc/tcg-target.c

@@ -437,7 +437,7 @@ enum {
     CR_SO
 };
 
-static const uint32_t tcg_to_bc[10] = {
+static const uint32_t tcg_to_bc[] = {
     [TCG_COND_EQ]  = BC | BI (7, CR_EQ) | BO_COND_TRUE,
     [TCG_COND_NE]  = BC | BI (7, CR_EQ) | BO_COND_FALSE,
     [TCG_COND_LT]  = BC | BI (7, CR_LT) | BO_COND_TRUE,

tcg/ppc64/tcg-target.c

@@ -418,7 +418,7 @@ enum {
     CR_SO
 };
 
-static const uint32_t tcg_to_bc[10] = {
+static const uint32_t tcg_to_bc[] = {
     [TCG_COND_EQ]  = BC | BI (7, CR_EQ) | BO_COND_TRUE,
     [TCG_COND_NE]  = BC | BI (7, CR_EQ) | BO_COND_FALSE,
     [TCG_COND_LT]  = BC | BI (7, CR_LT) | BO_COND_TRUE,

tcg/s390/tcg-target.c

@@ -268,7 +268,7 @@ static const int tcg_target_call_oarg_regs[] = {
 #define S390_CC_ALWAYS  15
 
 /* Condition codes that result from a COMPARE and COMPARE LOGICAL.  */
-static const uint8_t tcg_cond_to_s390_cond[10] = {
+static const uint8_t tcg_cond_to_s390_cond[] = {
     [TCG_COND_EQ]  = S390_CC_EQ,
     [TCG_COND_NE]  = S390_CC_NE,
     [TCG_COND_LT]  = S390_CC_LT,
@@ -284,7 +284,7 @@ static const uint8_t tcg_cond_to_s390_cond[10] = {
 /* Condition codes that result from a LOAD AND TEST.  Here, we have no
    unsigned instruction variation, however since the test is vs zero we
    can re-map the outcomes appropriately.  */
-static const uint8_t tcg_cond_to_ltr_cond[10] = {
+static const uint8_t tcg_cond_to_ltr_cond[] = {
     [TCG_COND_EQ]  = S390_CC_EQ,
     [TCG_COND_NE]  = S390_CC_NE,
     [TCG_COND_LT]  = S390_CC_LT,

tcg/sparc/tcg-target.c

@@ -512,7 +512,7 @@ static void tcg_out_branch_i64(TCGContext *s, int opc, int label_index)
 }
 #endif
 
-static const uint8_t tcg_cond_to_bcond[10] = {
+static const uint8_t tcg_cond_to_bcond[] = {
     [TCG_COND_EQ] = COND_E,
     [TCG_COND_NE] = COND_NE,
     [TCG_COND_LT] = COND_L,

tcg/tcg-op.h

@@ -646,29 +646,49 @@ static inline void tcg_gen_sari_i32(TCGv_i32 ret, TCGv_i32 arg1, int32_t arg2)
 static inline void tcg_gen_brcond_i32(TCGCond cond, TCGv_i32 arg1,
                                       TCGv_i32 arg2, int label_index)
 {
-    tcg_gen_op4ii_i32(INDEX_op_brcond_i32, arg1, arg2, cond, label_index);
+    if (cond == TCG_COND_ALWAYS) {
+        tcg_gen_br(label_index);
+    } else if (cond != TCG_COND_NEVER) {
+        tcg_gen_op4ii_i32(INDEX_op_brcond_i32, arg1, arg2, cond, label_index);
+    }
 }
 
 static inline void tcg_gen_brcondi_i32(TCGCond cond, TCGv_i32 arg1,
                                        int32_t arg2, int label_index)
 {
-    TCGv_i32 t0 = tcg_const_i32(arg2);
+    if (cond == TCG_COND_ALWAYS) {
-    tcg_gen_brcond_i32(cond, arg1, t0, label_index);
+        tcg_gen_br(label_index);
-    tcg_temp_free_i32(t0);
+    } else if (cond != TCG_COND_NEVER) {
+        TCGv_i32 t0 = tcg_const_i32(arg2);
+        tcg_gen_brcond_i32(cond, arg1, t0, label_index);
+        tcg_temp_free_i32(t0);
+    }
 }
 
 static inline void tcg_gen_setcond_i32(TCGCond cond, TCGv_i32 ret,
                                        TCGv_i32 arg1, TCGv_i32 arg2)
 {
-    tcg_gen_op4i_i32(INDEX_op_setcond_i32, ret, arg1, arg2, cond);
+    if (cond == TCG_COND_ALWAYS) {
+        tcg_gen_movi_i32(ret, 1);
+    } else if (cond == TCG_COND_NEVER) {
+        tcg_gen_movi_i32(ret, 0);
+    } else {
+        tcg_gen_op4i_i32(INDEX_op_setcond_i32, ret, arg1, arg2, cond);
+    }
 }
 
 static inline void tcg_gen_setcondi_i32(TCGCond cond, TCGv_i32 ret,
                                         TCGv_i32 arg1, int32_t arg2)
 {
-    TCGv_i32 t0 = tcg_const_i32(arg2);
+    if (cond == TCG_COND_ALWAYS) {
-    tcg_gen_setcond_i32(cond, ret, arg1, t0);
+        tcg_gen_movi_i32(ret, 1);
-    tcg_temp_free_i32(t0);
+    } else if (cond == TCG_COND_NEVER) {
+        tcg_gen_movi_i32(ret, 0);
+    } else {
+        TCGv_i32 t0 = tcg_const_i32(arg2);
+        tcg_gen_setcond_i32(cond, ret, arg1, t0);
+        tcg_temp_free_i32(t0);
+    }
 }
 
 static inline void tcg_gen_mul_i32(TCGv_i32 ret, TCGv_i32 arg1, TCGv_i32 arg2)
@@ -964,17 +984,27 @@ static inline void tcg_gen_sari_i64(TCGv_i64 ret, TCGv_i64 arg1, int64_t arg2)
 static inline void tcg_gen_brcond_i64(TCGCond cond, TCGv_i64 arg1,
                                       TCGv_i64 arg2, int label_index)
 {
-    tcg_gen_op6ii_i32(INDEX_op_brcond2_i32,
+    if (cond == TCG_COND_ALWAYS) {
-                      TCGV_LOW(arg1), TCGV_HIGH(arg1), TCGV_LOW(arg2),
+        tcg_gen_br(label_index);
-                      TCGV_HIGH(arg2), cond, label_index);
+    } else if (cond != TCG_COND_NEVER) {
+        tcg_gen_op6ii_i32(INDEX_op_brcond2_i32,
+                          TCGV_LOW(arg1), TCGV_HIGH(arg1), TCGV_LOW(arg2),
+                          TCGV_HIGH(arg2), cond, label_index);
+    }
 }
 
 static inline void tcg_gen_setcond_i64(TCGCond cond, TCGv_i64 ret,
                                        TCGv_i64 arg1, TCGv_i64 arg2)
 {
-    tcg_gen_op6i_i32(INDEX_op_setcond2_i32, TCGV_LOW(ret),
+    if (cond == TCG_COND_ALWAYS) {
-                     TCGV_LOW(arg1), TCGV_HIGH(arg1),
+        tcg_gen_movi_i32(TCGV_LOW(ret), 1);
-                     TCGV_LOW(arg2), TCGV_HIGH(arg2), cond);
+    } else if (cond == TCG_COND_NEVER) {
+        tcg_gen_movi_i32(TCGV_LOW(ret), 0);
+    } else {
+        tcg_gen_op6i_i32(INDEX_op_setcond2_i32, TCGV_LOW(ret),
+                         TCGV_LOW(arg1), TCGV_HIGH(arg1),
+                         TCGV_LOW(arg2), TCGV_HIGH(arg2), cond);
+    }
     tcg_gen_movi_i32(TCGV_HIGH(ret), 0);
 }
 
@@ -1273,13 +1303,23 @@ static inline void tcg_gen_sari_i64(TCGv_i64 ret, TCGv_i64 arg1, int64_t arg2)
 static inline void tcg_gen_brcond_i64(TCGCond cond, TCGv_i64 arg1,
                                       TCGv_i64 arg2, int label_index)
 {
-    tcg_gen_op4ii_i64(INDEX_op_brcond_i64, arg1, arg2, cond, label_index);
+    if (cond == TCG_COND_ALWAYS) {
+        tcg_gen_br(label_index);
+    } else if (cond != TCG_COND_NEVER) {
+        tcg_gen_op4ii_i64(INDEX_op_brcond_i64, arg1, arg2, cond, label_index);
+    }
 }
 
 static inline void tcg_gen_setcond_i64(TCGCond cond, TCGv_i64 ret,
                                        TCGv_i64 arg1, TCGv_i64 arg2)
 {
-    tcg_gen_op4i_i64(INDEX_op_setcond_i64, ret, arg1, arg2, cond);
+    if (cond == TCG_COND_ALWAYS) {
+        tcg_gen_movi_i64(ret, 1);
+    } else if (cond == TCG_COND_NEVER) {
+        tcg_gen_movi_i64(ret, 0);
+    } else {
+        tcg_gen_op4i_i64(INDEX_op_setcond_i64, ret, arg1, arg2, cond);
+    }
 }
 
 static inline void tcg_gen_mul_i64(TCGv_i64 ret, TCGv_i64 arg1, TCGv_i64 arg2)
@@ -1397,9 +1437,13 @@ static inline void tcg_gen_subi_i64(TCGv_i64 ret, TCGv_i64 arg1, int64_t arg2)
 static inline void tcg_gen_brcondi_i64(TCGCond cond, TCGv_i64 arg1,
                                        int64_t arg2, int label_index)
 {
-    TCGv_i64 t0 = tcg_const_i64(arg2);
+    if (cond == TCG_COND_ALWAYS) {
-    tcg_gen_brcond_i64(cond, arg1, t0, label_index);
+        tcg_gen_br(label_index);
-    tcg_temp_free_i64(t0);
+    } else if (cond != TCG_COND_NEVER) {
+        TCGv_i64 t0 = tcg_const_i64(arg2);
+        tcg_gen_brcond_i64(cond, arg1, t0, label_index);
+        tcg_temp_free_i64(t0);
+    }
 }
 
 static inline void tcg_gen_setcondi_i64(TCGCond cond, TCGv_i64 ret,

tcg/tcg.c

@@ -864,6 +864,8 @@ static TCGHelperInfo *tcg_find_helper(TCGContext *s, tcg_target_ulong val)
 
 static const char * const cond_name[] =
 {
+    [TCG_COND_NEVER] = "never",
+    [TCG_COND_ALWAYS] = "always",
     [TCG_COND_EQ] = "eq",
     [TCG_COND_NE] = "ne",
     [TCG_COND_LT] = "lt",

tcg/tcg.h

@@ -266,18 +266,28 @@ typedef int TCGv_i64;
 #define TCG_CALL_DUMMY_TCGV     MAKE_TCGV_I32(-1)
 #define TCG_CALL_DUMMY_ARG      ((TCGArg)(-1))
 
+/* Conditions.  Note that these are layed out for easy manipulation by
+   the the functions below:
+     bit 0 is used for inverting;
+     bit 1 is signed,
+     bit 2 is unsigned,
+     bit 3 is used with bit 0 for swapping signed/unsigned.  */
 typedef enum {
-    TCG_COND_EQ,
+    /* non-signed */
-    TCG_COND_NE,
+    TCG_COND_NEVER  = 0 | 0 | 0 | 0,
-    TCG_COND_LT,
+    TCG_COND_ALWAYS = 0 | 0 | 0 | 1,
-    TCG_COND_GE,
+    TCG_COND_EQ     = 8 | 0 | 0 | 0,
-    TCG_COND_LE,
+    TCG_COND_NE     = 8 | 0 | 0 | 1,
-    TCG_COND_GT,
+    /* signed */
+    TCG_COND_LT     = 0 | 0 | 2 | 0,
+    TCG_COND_GE     = 0 | 0 | 2 | 1,
+    TCG_COND_LE     = 8 | 0 | 2 | 0,
+    TCG_COND_GT     = 8 | 0 | 2 | 1,
     /* unsigned */
-    TCG_COND_LTU,
+    TCG_COND_LTU    = 0 | 4 | 0 | 0,
-    TCG_COND_GEU,
+    TCG_COND_GEU    = 0 | 4 | 0 | 1,
-    TCG_COND_LEU,
+    TCG_COND_LEU    = 8 | 4 | 0 | 0,
-    TCG_COND_GTU,
+    TCG_COND_GTU    = 8 | 4 | 0 | 1,
 } TCGCond;
 
 /* Invert the sense of the comparison.  */
@@ -289,18 +299,17 @@ static inline TCGCond tcg_invert_cond(TCGCond c)
 /* Swap the operands in a comparison.  */
 static inline TCGCond tcg_swap_cond(TCGCond c)
 {
-    int mask = (c < TCG_COND_LT ? 0 : c < TCG_COND_LTU ? 7 : 15);
+    return c & 6 ? (TCGCond)(c ^ 9) : c;
-    return (TCGCond)(c ^ mask);
 }
 
 static inline TCGCond tcg_unsigned_cond(TCGCond c)
 {
-    return (c >= TCG_COND_LT && c <= TCG_COND_GT ? c + 4 : c);
+    return c & 2 ? (TCGCond)(c ^ 6) : c;
 }
 
 static inline bool is_unsigned_cond(TCGCond c)
 {
-    return c >= TCG_COND_LTU;
+    return (c & 4) != 0;
 }
 
 #define TEMP_VAL_DEAD  0