[Qemu-devel] [PATCH] tcg: correct 32-bit tcg_gen_ld8s_i64 sign-extension

[Joseph Myers]

The version of tcg_gen_ld8s_i64 for 32-bit systems does a load into
the low part of the return value - then attempts a sign extension into
the high part, but wrongly sets the high part to a sign extension of
itself rather than of the low part.  This results in TCG internal
errors from the use of the uninitialized high part (in some GCC tests
of AArch64 NEON shift intrinsics, in particular).  This patch corrects
the sign-extension logic, making it match other functions such as
tcg_gen_ld16s_i64.

Signed-off-by: Joseph Myers <address@hidden>

---

diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c
index bb2bfee..43d34ea 100644
--- a/tcg/tcg-op.c
+++ b/tcg/tcg-op.c
@@ -790,7 +790,7 @@ void tcg_gen_ld8u_i64(TCGv_i64 ret, TCGv_ptr arg2, 
tcg_target_long offset)
 void tcg_gen_ld8s_i64(TCGv_i64 ret, TCGv_ptr arg2, tcg_target_long offset)
 {
     tcg_gen_ld8s_i32(TCGV_LOW(ret), arg2, offset);
-    tcg_gen_sari_i32(TCGV_HIGH(ret), TCGV_HIGH(ret), 31);
+    tcg_gen_sari_i32(TCGV_HIGH(ret), TCGV_LOW(ret), 31);
 }
 
 void tcg_gen_ld16u_i64(TCGv_i64 ret, TCGv_ptr arg2, tcg_target_long offset)

-- 
Joseph S. Myers
address@hidden