9290838132
Fix segfault with zero length virtio-scsi disk (bz #847549)
44 lines
1.6 KiB
Diff
44 lines
1.6 KiB
Diff
From 363479b4d4f729959eafb1209d48ad75e928c00a Mon Sep 17 00:00:00 2001
|
|
From: Aurelien Jarno <aurelien@aurel32.net>
|
|
Date: Tue, 18 Sep 2012 19:12:36 +0200
|
|
Subject: [PATCH] tcg/optimize: optimize "op r, a, a => movi r, 0"
|
|
|
|
Now that it's possible to detect copies, we can optimize the case
|
|
the "op r, a, a => movi r, 0". This helps in the computation of
|
|
overflow flags when one of the two args is 0.
|
|
|
|
Reviewed-by: Richard Henderson <rth@twiddle.net>
|
|
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
|
|
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
|
|
---
|
|
tcg/optimize.c | 16 ++++++++++++++++
|
|
1 file changed, 16 insertions(+)
|
|
|
|
diff --git a/tcg/optimize.c b/tcg/optimize.c
|
|
index b9a7da9..ceea644 100644
|
|
--- a/tcg/optimize.c
|
|
+++ b/tcg/optimize.c
|
|
@@ -540,6 +540,22 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
|
|
break;
|
|
}
|
|
|
|
+ /* Simplify expression for "op r, a, a => movi r, 0" cases */
|
|
+ switch (op) {
|
|
+ CASE_OP_32_64(sub):
|
|
+ CASE_OP_32_64(xor):
|
|
+ if (temps_are_copies(args[1], args[2])) {
|
|
+ gen_opc_buf[op_index] = op_to_movi(op);
|
|
+ tcg_opt_gen_movi(gen_args, args[0], 0);
|
|
+ gen_args += 2;
|
|
+ args += 3;
|
|
+ continue;
|
|
+ }
|
|
+ break;
|
|
+ default:
|
|
+ break;
|
|
+ }
|
|
+
|
|
/* Propagate constants through copy operations and do constant
|
|
folding. Constants will be substituted to arguments by register
|
|
allocator where needed and possible. Also detect copies. */
|