[Qemu-devel] [PATCH] Support saturation with shift=0.

[Christophe Lyon]

This patch fixes corner-case saturations, when the target range is
zero. It merely removes the guard against (sh == 0), and makes:
__ssat(0x87654321, 1) return 0xffffffff and set the saturation flag
__usat(0x87654321, 0) return 0 and set the saturation flag

Signed-off-by: Christophe Lyon <address@hidden>
---
 target-arm/translate.c |   28 ++++++++++++----------------
 1 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/target-arm/translate.c b/target-arm/translate.c
index 721bada..41cbb96 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -6896,27 +6896,23 @@ static void disas_arm_insn(CPUState * env, DisasContext 
*s)
                             tcg_gen_shli_i32(tmp, tmp, shift);
                         }
                         sh = (insn >> 16) & 0x1f;
-                        if (sh != 0) {
-                            tmp2 = tcg_const_i32(sh);
-                            if (insn & (1 << 22))
-                                gen_helper_usat(tmp, tmp, tmp2);
-                            else
-                                gen_helper_ssat(tmp, tmp, tmp2);
-                            tcg_temp_free_i32(tmp2);
-                        }
+                        tmp2 = tcg_const_i32(sh);
+                        if (insn & (1 << 22))
+                          gen_helper_usat(tmp, tmp, tmp2);
+                        else
+                          gen_helper_ssat(tmp, tmp, tmp2);
+                        tcg_temp_free_i32(tmp2);
                         store_reg(s, rd, tmp);
                     } else if ((insn & 0x00300fe0) == 0x00200f20) {
                         /* [us]sat16 */
                         tmp = load_reg(s, rm);
                         sh = (insn >> 16) & 0x1f;
-                        if (sh != 0) {
-                            tmp2 = tcg_const_i32(sh);
-                            if (insn & (1 << 22))
-                                gen_helper_usat16(tmp, tmp, tmp2);
-                            else
-                                gen_helper_ssat16(tmp, tmp, tmp2);
-                            tcg_temp_free_i32(tmp2);
-                        }
+                        tmp2 = tcg_const_i32(sh);
+                        if (insn & (1 << 22))
+                          gen_helper_usat16(tmp, tmp, tmp2);
+                        else
+                          gen_helper_ssat16(tmp, tmp, tmp2);
+                        tcg_temp_free_i32(tmp2);
                         store_reg(s, rd, tmp);
                     } else if ((insn & 0x00700fe0) == 0x00000fa0) {
                         /* Select bytes.  */
-- 
1.7.2.3