target/i386: Wrap cc_op_live with a validity check

Assert that op is known and that cc_op_live_ is populated.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

4 files changed, 21 insertions, 7 deletions

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 1bf4dfdc5b..a0a122cb5b 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1380,7 +1380,6 @@ typedef enum {
 #define CC_OP_LAST_BWLQ CC_OP_POPCNTQ__
 
     CC_OP_DYNAMIC, /* must use dynamic code to get cc_op */
-    CC_OP_NB,
 } CCOp;
 
 /* See X86DecodedInsn.cc_op, using int8_t. */
diff --git a/target/i386/tcg/decode-new.c.inc b/target/i386/tcg/decode-new.c.inc
index 48bf730cd3..cda32ee678 100644
--- a/target/i386/tcg/decode-new.c.inc
+++ b/target/i386/tcg/decode-new.c.inc
@@ -2865,7 +2865,7 @@ static void disas_insn(DisasContext *s, CPUState *cpu)
             tcg_gen_mov_i32(cpu_cc_op, decode.cc_op_dynamic);
         }
         set_cc_op(s, decode.cc_op);
-        cc_live = cc_op_live[decode.cc_op];
+        cc_live = cc_op_live(decode.cc_op);
     } else {
         cc_live = 0;
     }
diff --git a/target/i386/tcg/emit.c.inc b/target/i386/tcg/emit.c.inc
index 45ac5edb1a..785ff63f2a 100644
--- a/target/i386/tcg/emit.c.inc
+++ b/target/i386/tcg/emit.c.inc
@@ -3777,13 +3777,13 @@ static void gen_shift_dynamic_flags(DisasContext *s, X86DecodedInsn *decode, TCG
     decode->cc_op_dynamic = tcg_temp_new_i32();
 
     assert(decode->cc_dst == s->T0);
-    if (cc_op_live[s->cc_op] & USES_CC_DST) {
+    if (cc_op_live(s->cc_op) & USES_CC_DST) {
         decode->cc_dst = tcg_temp_new();
         tcg_gen_movcond_tl(TCG_COND_EQ, decode->cc_dst, count, tcg_constant_tl(0),
                            cpu_cc_dst, s->T0);
     }
 
-    if (cc_op_live[s->cc_op] & USES_CC_SRC) {
+    if (cc_op_live(s->cc_op) & USES_CC_SRC) {
         tcg_gen_movcond_tl(TCG_COND_EQ, decode->cc_src, count, tcg_constant_tl(0),
                            cpu_cc_src, decode->cc_src);
     }
diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c
index 46062002c0..1a9a2fe709 100644
--- a/target/i386/tcg/translate.c
+++ b/target/i386/tcg/translate.c
@@ -291,7 +291,7 @@ enum {
 };
 
 /* Bit set if the global variable is live after setting CC_OP to X.  */
-static const uint8_t cc_op_live[CC_OP_NB] = {
+static const uint8_t cc_op_live_[] = {
     [CC_OP_DYNAMIC] = USES_CC_DST | USES_CC_SRC | USES_CC_SRC2,
     [CC_OP_EFLAGS] = USES_CC_SRC,
     [CC_OP_MULB ... CC_OP_MULQ] = USES_CC_DST | USES_CC_SRC,
@@ -312,6 +312,21 @@ static const uint8_t cc_op_live[CC_OP_NB] = {
     [CC_OP_POPCNT] = USES_CC_DST,
 };
 
+static uint8_t cc_op_live(CCOp op)
+{
+    uint8_t result;
+    assert(op >= 0 && op < ARRAY_SIZE(cc_op_live_));
+
+    /*
+     * Check that the array is fully populated.  A zero entry would correspond
+     * to a fixed value of EFLAGS, which can be obtained with CC_OP_EFLAGS
+     * as well.
+     */
+    result = cc_op_live_[op];
+    assert(result);
+    return result;
+}
+
 static void set_cc_op_1(DisasContext *s, CCOp op, bool dirty)
 {
     int dead;
@@ -321,7 +336,7 @@ static void set_cc_op_1(DisasContext *s, CCOp op, bool dirty)
     }
 
     /* Discard CC computation that will no longer be used.  */
-    dead = cc_op_live[s->cc_op] & ~cc_op_live[op];
+    dead = cc_op_live(s->cc_op) & ~cc_op_live(op);
     if (dead & USES_CC_DST) {
         tcg_gen_discard_tl(cpu_cc_dst);
     }
@@ -808,7 +823,7 @@ static void gen_mov_eflags(DisasContext *s, TCGv reg)
     src2 = cpu_cc_src2;
 
     /* Take care to not read values that are not live.  */
-    live = cc_op_live[s->cc_op] & ~USES_CC_SRCT;
+    live = cc_op_live(s->cc_op) & ~USES_CC_SRCT;
     dead = live ^ (USES_CC_DST | USES_CC_SRC | USES_CC_SRC2);
     if (dead) {
         TCGv zero = tcg_constant_tl(0);