[Qemu-devel] [PATCH] target-sparc: fix udiv(cc) and sdiv(cc)

[Aurelien Jarno]

Since commit 5a4bb580cdb10b066f9fd67658b31cac4a4ea5e5, Xorg crashes on
a Debian Etch image. The commit itself is fine, but it triggers a bug
due to wrong computation of flags for udiv(cc) and sdiv(cc).

This patch only compute cc_src2 for the cc version of udiv/sdiv. It
also moves the update of cc_dst and cc_op to the helper, as it is
faster doing it here when there is already an helper.

Signed-off-by: Aurelien Jarno <address@hidden>
---
 target-sparc/helper.h    |    2 +
 target-sparc/op_helper.c |   54 +++++++++++++++++++++++++++++++++++----------
 target-sparc/translate.c |   12 +++++-----
 3 files changed, 50 insertions(+), 18 deletions(-)

diff --git a/target-sparc/helper.h b/target-sparc/helper.h
index 6f103e7..e6d82f9 100644
--- a/target-sparc/helper.h
+++ b/target-sparc/helper.h
@@ -37,7 +37,9 @@ DEF_HELPER_0(save, void)
 DEF_HELPER_0(restore, void)
 DEF_HELPER_1(flush, void, tl)
 DEF_HELPER_2(udiv, tl, tl, tl)
+DEF_HELPER_2(udiv_cc, tl, tl, tl)
 DEF_HELPER_2(sdiv, tl, tl, tl)
+DEF_HELPER_2(sdiv_cc, tl, tl, tl)
 DEF_HELPER_2(stdf, void, tl, int)
 DEF_HELPER_2(lddf, void, tl, int)
 DEF_HELPER_2(ldqf, void, tl, int)
diff --git a/target-sparc/op_helper.c b/target-sparc/op_helper.c
index 4f753ba..58f9f82 100644
--- a/target-sparc/op_helper.c
+++ b/target-sparc/op_helper.c
@@ -3300,8 +3300,9 @@ void helper_rett(void)
 }
 #endif
 
-target_ulong helper_udiv(target_ulong a, target_ulong b)
+static target_ulong helper_udiv_common(target_ulong a, target_ulong b, int cc)
 {
+    int overflow = 0;
     uint64_t x0;
     uint32_t x1;
 
@@ -3314,16 +3315,31 @@ target_ulong helper_udiv(target_ulong a, target_ulong b)
 
     x0 = x0 / x1;
     if (x0 > 0xffffffff) {
-        env->cc_src2 = 1;
-        return 0xffffffff;
-    } else {
-        env->cc_src2 = 0;
-        return x0;
+        x0 = 0xffffffff;
+        overflow = 1;
+    }
+
+    if (cc) {
+        env->cc_dst = x0;
+        env->cc_src2 = overflow;
+        env->cc_op = CC_OP_DIV;
     }
+    return x0;
 }
 
-target_ulong helper_sdiv(target_ulong a, target_ulong b)
+target_ulong helper_udiv(target_ulong a, target_ulong b)
+{
+    return helper_udiv_common(a, b, 0);
+}
+
+target_ulong helper_udiv_cc(target_ulong a, target_ulong b)
+{
+    return helper_udiv_common(a, b, 1);
+}
+
+static target_ulong helper_sdiv_common(target_ulong a, target_ulong b, int cc)
 {
+    int overflow = 0;
     int64_t x0;
     int32_t x1;
 
@@ -3336,12 +3352,26 @@ target_ulong helper_sdiv(target_ulong a, target_ulong b)
 
     x0 = x0 / x1;
     if ((int32_t) x0 != x0) {
-        env->cc_src2 = 1;
-        return x0 < 0? 0x80000000: 0x7fffffff;
-    } else {
-        env->cc_src2 = 0;
-        return x0;
+        x0 = x0 < 0 ? 0x80000000: 0x7fffffff;
+        overflow = 1;
+    }
+
+    if (cc) {
+        env->cc_dst = x0;
+        env->cc_src2 = overflow;
+        env->cc_op = CC_OP_DIV;
     }
+    return x0;
+}
+
+target_ulong helper_sdiv(target_ulong a, target_ulong b)
+{
+    return helper_sdiv_common(a, b, 0);
+}
+
+target_ulong helper_sdiv_cc(target_ulong a, target_ulong b)
+{
+    return helper_sdiv_common(a, b, 1);
 }
 
 void helper_stdf(target_ulong addr, int mem_idx)
diff --git a/target-sparc/translate.c b/target-sparc/translate.c
index 23f9519..21c5675 100644
--- a/target-sparc/translate.c
+++ b/target-sparc/translate.c
@@ -3162,20 +3162,20 @@ static void disas_sparc_insn(DisasContext * dc)
 #endif
                     case 0xe: /* udiv */
                         CHECK_IU_FEATURE(dc, DIV);
-                        gen_helper_udiv(cpu_dst, cpu_src1, cpu_src2);
                         if (xop & 0x10) {
-                            tcg_gen_mov_tl(cpu_cc_dst, cpu_dst);
-                            tcg_gen_movi_i32(cpu_cc_op, CC_OP_DIV);
+                            gen_helper_udiv_cc(cpu_dst, cpu_src1, cpu_src2);
                             dc->cc_op = CC_OP_DIV;
+                        } else {
+                            gen_helper_udiv(cpu_dst, cpu_src1, cpu_src2);
                         }
                         break;
                     case 0xf: /* sdiv */
                         CHECK_IU_FEATURE(dc, DIV);
-                        gen_helper_sdiv(cpu_dst, cpu_src1, cpu_src2);
                         if (xop & 0x10) {
-                            tcg_gen_mov_tl(cpu_cc_dst, cpu_dst);
-                            tcg_gen_movi_i32(cpu_cc_op, CC_OP_DIV);
+                            gen_helper_sdiv_cc(cpu_dst, cpu_src1, cpu_src2);
                             dc->cc_op = CC_OP_DIV;
+                        } else {
+                            gen_helper_sdiv(cpu_dst, cpu_src1, cpu_src2);
                         }
                         break;
                     default:
-- 
1.7.2.3