[Qemu-devel] [PATCH 15/15] tcg: use ext op for deposit

[Alexander Graf]

With the s390x target we use the deposit instruction to store 32bit values
into 64bit registers without clobbering the upper 32 bits.

This specific operation can be optimized slightly by using the ext operation
instead of an explicit and in the deposit instruction. This patch adds that
special case to the generic deposit implementation.

Signed-off-by: Alexander Graf <address@hidden>
---
 tcg/tcg-op.h |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/tcg/tcg-op.h b/tcg/tcg-op.h
index 207a89f..88575e7 100644
--- a/tcg/tcg-op.h
+++ b/tcg/tcg-op.h
@@ -2124,7 +2124,11 @@ static inline void tcg_gen_deposit_i64(TCGv_i64 ret, 
TCGv_i64 arg1,
   uint64_t mask = (1ull << len) - 1;
   TCGv_i64 t1 = tcg_temp_new_i64 ();
 
-  tcg_gen_andi_i64(t1, arg2, mask);
+  if (len == 32) {
+       tcg_gen_ext32u_i64(t1, arg2);
+  } else {
+      tcg_gen_andi_i64(t1, arg2, mask);
+  }
   tcg_gen_shli_i64(t1, t1, ofs);
   tcg_gen_andi_i64(ret, arg1, ~(mask << ofs));
   tcg_gen_or_i64(ret, ret, t1);
-- 
1.6.0.2