tcg: fix deposit_i64 op on 32-bit targets

On 32-bit TCG targets, when emulating deposit_i64 with a mov_i32 +
deposit_i32, care should be taken to not overwrite the low part of
the second argument before the deposit when it is the same the
destination.

This fixes the shld instruction in qemu-system-x86_64, which in turns
fixes booting "system rescue CD version 2.8.0" on this target.

Reported-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

diff --git a/tcg/tcg-op.h b/tcg/tcg-op.h
index d70b2eba33518669f14585fde202eb983c380894..94f6043786bbbb9b0fd2cfa721393ea6d13eda50 100644 (file)
--- a/tcg/tcg-op.h
+++ b/tcg/tcg-op.h
@@ -2188,9 +2188,9 @@ static inline void tcg_gen_deposit_i64(TCGv_i64 ret, TCGv_i64 arg1,
 
 #if TCG_TARGET_REG_BITS == 32
     if (ofs >= 32) {
-        tcg_gen_mov_i32(TCGV_LOW(ret), TCGV_LOW(arg1));
         tcg_gen_deposit_i32(TCGV_HIGH(ret), TCGV_HIGH(arg1),
                             TCGV_LOW(arg2), ofs - 32, len);
+        tcg_gen_mov_i32(TCGV_LOW(ret), TCGV_LOW(arg1));
         return;
     }
     if (ofs + len <= 32) {