[Qemu-devel] [PATCH] target-xtensa: fix big-endian BBS/BBC implementation

[Max Filippov]

Quote from ISA, 2.1:

For most Xtensa instructions, bit numbering is irrelevant; only the BBC
and BBS instructions assign bit numbers to values on which the processor
operates. The BBC/BBS instructions use big-endian bit ordering (0 is the
most-significant bit) on a big-endian processor configuration.

Signed-off-by: Max Filippov <address@hidden>
---
This is also applicable to qemu-stable 1.0 and 1.1

 target-xtensa/translate.c |   16 ++++++++++++++--
 1 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/target-xtensa/translate.c b/target-xtensa/translate.c
index b883e6b..1900bd5 100644
--- a/target-xtensa/translate.c
+++ b/target-xtensa/translate.c
@@ -2366,10 +2366,18 @@ static void disas_xtensa_insn(DisasContext *dc)
             case 5: /*BBC*/ /*BBS*/
                 gen_window_check2(dc, RRI8_S, RRI8_T);
                 {
-                    TCGv_i32 bit = tcg_const_i32(1);
+#ifdef TARGET_WORDS_BIGENDIAN
+                    TCGv_i32 bit = tcg_const_i32(0x80000000);
+#else
+                    TCGv_i32 bit = tcg_const_i32(0x00000001);
+#endif
                     TCGv_i32 tmp = tcg_temp_new_i32();
                     tcg_gen_andi_i32(tmp, cpu_R[RRI8_T], 0x1f);
+#ifdef TARGET_WORDS_BIGENDIAN
+                    tcg_gen_shr_i32(bit, bit, tmp);
+#else
                     tcg_gen_shl_i32(bit, bit, tmp);
+#endif
                     tcg_gen_and_i32(tmp, cpu_R[RRI8_S], bit);
                     gen_brcondi(dc, eq_ne, tmp, 0, 4 + RRI8_IMM8_SE);
                     tcg_temp_free(tmp);
@@ -2383,7 +2391,11 @@ static void disas_xtensa_insn(DisasContext *dc)
                 {
                     TCGv_i32 tmp = tcg_temp_new_i32();
                     tcg_gen_andi_i32(tmp, cpu_R[RRI8_S],
-                            1 << (((RRI8_R & 1) << 4) | RRI8_T));
+#ifdef TARGET_WORDS_BIGENDIAN
+                            0x80000000 >> (((RRI8_R & 1) << 4) | RRI8_T));
+#else
+                            0x00000001 << (((RRI8_R & 1) << 4) | RRI8_T));
+#endif
                     gen_brcondi(dc, eq_ne, tmp, 0, 4 + RRI8_IMM8_SE);
                     tcg_temp_free(tmp);
                 }
-- 
1.7.7.6