[Qemu-devel] [PATCH v4] target/ppc: Fix carry flag setting for shift algebraic instructions

[Sandipan Das <sandipan@linux.vnet.ibm.com>]

For POWER ISA v3.0, the XER bit CA32 needs to be set by the shift
right algebraic instructions whenever the CA bit is to be set. This
change affects the following instructions:
  * Shift Right Algebraic Word (sraw[.])
  * Shift Right Algebraic Word Immediate (srawi[.])
  * Shift Right Algebraic Doubleword (srad[.])
  * Shift Right Algebraic Doubleword Immediate (sradi[.])

Signed-off-by: Sandipan Das <sandipan@linux.vnet.ibm.com>
---
v2: Add tcg_temp_free() required in gen_sraw() and gen_srad()

v3: Remove explicit checking for ISA v3.0 when setting CA32

v4: Set CA32 only when CA is being modified (as Richard suggested)
    Set CA32 after checking for ISA300 in gen_* functions (as David suggested)
---
 target/ppc/int_helper.c | 16 ++++++++--------
 target/ppc/translate.c  | 12 ++++++++++++
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/target/ppc/int_helper.c b/target/ppc/int_helper.c
index da4e1a62c9..1c013a0ee3 100644
--- a/target/ppc/int_helper.c
+++ b/target/ppc/int_helper.c
@@ -219,17 +219,17 @@ target_ulong helper_sraw(CPUPPCState *env, target_ulong value,
             shift &= 0x1f;
             ret = (int32_t)value >> shift;
             if (likely(ret >= 0 || (value & ((1 << shift) - 1)) == 0)) {
-                env->ca = 0;
+                env->ca32 = env->ca = 0;
             } else {
-                env->ca = 1;
+                env->ca32 = env->ca = 1;
             }
         } else {
             ret = (int32_t)value;
-            env->ca = 0;
+            env->ca32 = env->ca = 0;
         }
     } else {
         ret = (int32_t)value >> 31;
-        env->ca = (ret != 0);
+        env->ca32 = env->ca = (ret != 0);
     }
     return (target_long)ret;
 }
@@ -245,17 +245,17 @@ target_ulong helper_srad(CPUPPCState *env, target_ulong value,
             shift &= 0x3f;
             ret = (int64_t)value >> shift;
             if (likely(ret >= 0 || (value & ((1ULL << shift) - 1)) == 0)) {
-                env->ca = 0;
+                env->ca32 = env->ca = 0;
             } else {
-                env->ca = 1;
+                env->ca32 = env->ca = 1;
             }
         } else {
             ret = (int64_t)value;
-            env->ca = 0;
+            env->ca32 = env->ca = 0;
         }
     } else {
         ret = (int64_t)value >> 63;
-        env->ca = (ret != 0);
+        env->ca32 = env->ca = (ret != 0);
     }
     return ret;
 }
diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index 606b605ba0..a81ff69d75 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -2181,6 +2181,9 @@ static void gen_srawi(DisasContext *ctx)
     if (sh == 0) {
         tcg_gen_ext32s_tl(dst, src);
         tcg_gen_movi_tl(cpu_ca, 0);
+        if (is_isa300(ctx)) {
+            tcg_gen_movi_tl(cpu_ca32, 0);
+        }
     } else {
         TCGv t0;
         tcg_gen_ext32s_tl(dst, src);
@@ -2190,6 +2193,9 @@ static void gen_srawi(DisasContext *ctx)
         tcg_gen_and_tl(cpu_ca, cpu_ca, t0);
         tcg_temp_free(t0);
         tcg_gen_setcondi_tl(TCG_COND_NE, cpu_ca, cpu_ca, 0);
+        if (is_isa300(ctx)) {
+            tcg_gen_mov_tl(cpu_ca32, cpu_ca);
+        }
         tcg_gen_sari_tl(dst, dst, sh);
     }
     if (unlikely(Rc(ctx->opcode) != 0)) {
@@ -2259,6 +2265,9 @@ static inline void gen_sradi(DisasContext *ctx, int n)
     if (sh == 0) {
         tcg_gen_mov_tl(dst, src);
         tcg_gen_movi_tl(cpu_ca, 0);
+        if (is_isa300(ctx)) {
+            tcg_gen_movi_tl(cpu_ca32, 0);
+        }
     } else {
         TCGv t0;
         tcg_gen_andi_tl(cpu_ca, src, (1ULL << sh) - 1);
@@ -2267,6 +2276,9 @@ static inline void gen_sradi(DisasContext *ctx, int n)
         tcg_gen_and_tl(cpu_ca, cpu_ca, t0);
         tcg_temp_free(t0);
         tcg_gen_setcondi_tl(TCG_COND_NE, cpu_ca, cpu_ca, 0);
+        if (is_isa300(ctx)) {
+            tcg_gen_mov_tl(cpu_ca32, cpu_ca);
+        }
         tcg_gen_sari_tl(dst, src, sh);
     }
     if (unlikely(Rc(ctx->opcode) != 0)) {
-- 
2.13.6