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[Qemu-devel] [PATCH RFC 6/9] tcg/i386: document the way 32/64-bit conver
From: |
Aurelien Jarno |
Subject: |
[Qemu-devel] [PATCH RFC 6/9] tcg/i386: document the way 32/64-bit conversions are handled |
Date: |
Wed, 15 Jul 2015 13:03:16 +0200 |
Cc: Paolo Bonzini <address@hidden>
Cc: Richard Henderson <address@hidden>
Signed-off-by: Aurelien Jarno <address@hidden>
---
tcg/i386/tcg-target.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/tcg/i386/tcg-target.h b/tcg/i386/tcg-target.h
index 16f3949..d483083 100644
--- a/tcg/i386/tcg-target.h
+++ b/tcg/i386/tcg-target.h
@@ -129,7 +129,11 @@ extern bool have_bmi1;
#define TCG_TARGET_HAS_muluh_i64 0
#define TCG_TARGET_HAS_mulsh_i64 0
-/* size changing optional ops */
+/* size changing optional ops. On x86 we ensure that all 32-bit ops
+ ignore the high bits. We therefore can implement trunc_shr_i64_i32
+ as a mov, but we need to implement ext_i32_i64 and extu_i32_i64 to
+ zero/sign extend the high bits when converting a 32-bit value into
+ a 64-bit one. */
#define TCG_TARGET_HAS_trunc_shr_i64_i32 0
#define TCG_TARGET_HAS_ext_i32_i64 1
#define TCG_TARGET_HAS_extu_i32_i64 1
--
2.1.4
- Re: [Qemu-devel] [PATCH RFC 1/9] tcg: rename trunc_shr_i32 into trunc_shr_i64_i32, (continued)
- [Qemu-devel] [PATCH RFC 3/9] tcg: implement real ext_i32_i64 and extu_i32_i64 ops, Aurelien Jarno, 2015/07/15
- [Qemu-devel] [PATCH RFC 5/9] tcg/i386: implement ext_i32_i64 and extu_i32_i64 ops, Aurelien Jarno, 2015/07/15
- [Qemu-devel] [PATCH RFC 8/9] tcg/optimize: do not simplify size changing moves, Aurelien Jarno, 2015/07/15
- [Qemu-devel] [PATCH RFC 7/9] tcg: replace ext/u_i32_i64 by a mov when not implemented, Aurelien Jarno, 2015/07/15
- [Qemu-devel] [PATCH RFC 9/9] tcg: update README about size changing ops, Aurelien Jarno, 2015/07/15
- [Qemu-devel] [PATCH RFC 4/9] tcg/optimize: add optimizations for ext_i32_i64 and extu_i32_i64 ops, Aurelien Jarno, 2015/07/15
- [Qemu-devel] [PATCH RFC 6/9] tcg/i386: document the way 32/64-bit conversions are handled,
Aurelien Jarno <=