Re: [Qemu-devel] [PATCH RFC 7/9] tcg: replace ext/u_i32_i64 by a mov when not implemented

[Richard Henderson]

On 07/15/2015 12:03 PM, Aurelien Jarno wrote:

When ext_i32_i64 and extu_i32_i64 ops are not implemented, this means
that the register is already properly zero/sign extended, so we can
simply replace it by a mov.

In practice it means at least one of the two ops should always be
implemented on 64-bit targets.

Cc: Paolo Bonzinipbonz...@redhat.com
Cc: Richard Hendersonr...@twiddle.net
Signed-off-by: Aurelien Jarnoaurel...@aurel32.net
---
  tcg/tcg-op.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)


If we're going to do this (and of course pick a solution for all of the other 
backends), I think perhaps x86 should choose trunc + exts as the two that 
should be implemented, leaving extu the one that can be folded away.


Something to experiment with...


r~

[Qemu-devel] [PATCH RFC 7/9] tcg: replace ext/u_i32_i64 by a mov when not implemented

[Aurelien Jarno]

When ext_i32_i64 and extu_i32_i64 ops are not implemented, this means
that the register is already properly zero/sign extended, so we can
simply replace it by a mov.

In practice it means at least one of the two ops should always be
implemented on 64-bit targets.

Cc: Paolo Bonzini pbonz...@redhat.com
Cc: Richard Henderson r...@twiddle.net
Signed-off-by: Aurelien Jarno aurel...@aurel32.net
---
 tcg/tcg-op.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c
index c8db812..b4b1654 100644
--- a/tcg/tcg-op.c
+++ b/tcg/tcg-op.c
@@ -1775,7 +1775,7 @@ void tcg_gen_extu_i32_i64(TCGv_i64 ret, TCGv_i32 arg)
 } else {
 /* Note: we assume the target supports move between
32 and 64 bit registers.  */
-tcg_gen_ext32u_i64(ret, MAKE_TCGV_I64(GET_TCGV_I32(arg)));
+tcg_gen_mov_i64(ret, MAKE_TCGV_I64(GET_TCGV_I32(arg)));
 }
 }
 
@@ -1790,7 +1790,7 @@ void tcg_gen_ext_i32_i64(TCGv_i64 ret, TCGv_i32 arg)
 } else {
 /* Note: we assume the target supports move between
32 and 64 bit registers.  */
-tcg_gen_ext32s_i64(ret, MAKE_TCGV_I64(GET_TCGV_I32(arg)));
+tcg_gen_mov_i64(ret, MAKE_TCGV_I64(GET_TCGV_I32(arg)));
 }
 }
 
-- 
2.1.4