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[Qemu-devel] [PATCH 14/16] tcg-i386: Remove "cb" output restriction from
From: |
Richard Henderson |
Subject: |
[Qemu-devel] [PATCH 14/16] tcg-i386: Remove "cb" output restriction from qemu_st8 for i386 |
Date: |
Wed, 4 Sep 2013 14:05:03 -0700 |
Once we form a combined qemu_st_i32 opcode, we won't be able to
have separate constraints based on size. This one is fairly easy
to work around, since eax is available as a scratch register.
When storing variable data, this tends to merely exchange one mov
for another. E.g.
-: mov %esi,%ecx
...
-: mov %cl,(%edx)
+: mov %esi,%eax
+: mov %al,(%edx)
Where we do have a regression is when storing constant data, in which
we may load the constant into edi, when only ecx/ebx ought to be used.
The proper way to recover this regression is to allow constants as
arguments to qemu_st_i32, so that we never load the constant data into
a register at all, must less the wrong register. TBD.
Signed-off-by: Richard Henderson <address@hidden>
---
tcg/i386/tcg-target.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c
index 89fe121..a3bf885 100644
--- a/tcg/i386/tcg-target.c
+++ b/tcg/i386/tcg-target.c
@@ -1503,6 +1503,12 @@ static void tcg_out_qemu_st_direct(TCGContext *s, TCGReg
datalo, TCGReg datahi,
switch (memop & MO_SIZE) {
case MO_8:
+ /* In 32-bit mode, 8-byte stores can only happen from [abcd]x.
+ Use the scratch register if necessary. */
+ if (TCG_TARGET_REG_BITS == 32 && datalo >= 4) {
+ tcg_out_mov(s, TCG_TYPE_I32, scratch, datalo);
+ datalo = scratch;
+ }
tcg_out_modrm_offset(s, OPC_MOVB_EvGv + P_REXB_R + seg,
datalo, base, ofs);
break;
@@ -2108,7 +2114,7 @@ static const TCGTargetOpDef x86_op_defs[] = {
{ INDEX_op_qemu_ld32, { "r", "L" } },
{ INDEX_op_qemu_ld64, { "r", "r", "L" } },
- { INDEX_op_qemu_st8, { "cb", "L" } },
+ { INDEX_op_qemu_st8, { "L", "L" } },
{ INDEX_op_qemu_st16, { "L", "L" } },
{ INDEX_op_qemu_st32, { "L", "L" } },
{ INDEX_op_qemu_st64, { "L", "L", "L" } },
@@ -2120,7 +2126,7 @@ static const TCGTargetOpDef x86_op_defs[] = {
{ INDEX_op_qemu_ld32, { "r", "L", "L" } },
{ INDEX_op_qemu_ld64, { "r", "r", "L", "L" } },
- { INDEX_op_qemu_st8, { "cb", "L", "L" } },
+ { INDEX_op_qemu_st8, { "L", "L", "L" } },
{ INDEX_op_qemu_st16, { "L", "L", "L" } },
{ INDEX_op_qemu_st32, { "L", "L", "L" } },
{ INDEX_op_qemu_st64, { "L", "L", "L", "L" } },
--
1.8.1.4
- [Qemu-devel] [PATCH 02/16] tcg-i386: Use TCGMemOp within qemu_ldst routines, (continued)
- [Qemu-devel] [PATCH 02/16] tcg-i386: Use TCGMemOp within qemu_ldst routines, Richard Henderson, 2013/09/04
- [Qemu-devel] [PATCH 01/16] tcg: Add TCGMemOp, Richard Henderson, 2013/09/04
- [Qemu-devel] [PATCH 05/16] tcg-s390: Use TCGMemOp within qemu_ldst routines, Richard Henderson, 2013/09/04
- [Qemu-devel] [PATCH 06/16] tcg-ppc: Use TCGMemOp within qemu_ldst routines, Richard Henderson, 2013/09/04
- [Qemu-devel] [PATCH 07/16] tcg-ppc64: Use TCGMemOp within qemu_ldst routines, Richard Henderson, 2013/09/04
- [Qemu-devel] [PATCH 08/16] tcg-hppa: Use TCGMemOp within qemu_ldst routines, Richard Henderson, 2013/09/04
- [Qemu-devel] [PATCH 09/16] tcg-mips: Use TCGMemOp within qemu_ldst routines, Richard Henderson, 2013/09/04
- [Qemu-devel] [PATCH 10/16] tcg-sparc: Use TCGMemOp within qemu_ldst routines, Richard Henderson, 2013/09/04
- [Qemu-devel] [PATCH 11/16] tcg: Add qemu_ld_st_i32/64, Richard Henderson, 2013/09/04
- [Qemu-devel] [PATCH 12/16] exec: Add both big- and little-endian memory helpers, Richard Henderson, 2013/09/04
- [Qemu-devel] [PATCH 14/16] tcg-i386: Remove "cb" output restriction from qemu_st8 for i386,
Richard Henderson <=
- [Qemu-devel] [PATCH 13/16] tcg-i386: Tidy softmmu routines, Richard Henderson, 2013/09/04
- [Qemu-devel] [PATCH 15/16] tcg-i386: Support new ldst opcodes, Richard Henderson, 2013/09/04
- [Qemu-devel] [PATCH 16/16] target-ppc: Convert to new ldst opcodes, Richard Henderson, 2013/09/04