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[PATCH] target/i386: Remove unnecessary checks of b2 in SSE decode
From: |
Peter Maydell |
Subject: |
[PATCH] target/i386: Remove unnecessary checks of b2 in SSE decode |
Date: |
Fri, 20 Aug 2021 18:12:20 +0100 |
In the SSE decode function gen_sse(), we combine a byte
'b' and a value 'b1' which can be [0..3], and switch on them:
b |= (b1 << 8);
switch (b) {
...
default:
unknown_op:
gen_unknown_opcode(env, s);
return;
}
In three cases inside this switch, we were then also checking for
"if (b1 >= 2) { goto unknown_op; }".
However, this can never happen, because the 'case' values in each place
are 0x0nn or 0x1nn and the switch will have directed the b1 == (2, 3)
cases to the default already.
Delete the dead code.
This check was added in commit c045af25a52e9 in 2010; the added code
was unnecessary then as well. this commit amounts to a revert of
c045af25a52e9.
Fixes: Coverity CID 1460207
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
Somebody should double-check this, because one assumes Andi
added the code for a reason...
---
target/i386/tcg/translate.c | 9 ---------
1 file changed, 9 deletions(-)
diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c
index aacb605eee4..3e7afd2620e 100644
--- a/target/i386/tcg/translate.c
+++ b/target/i386/tcg/translate.c
@@ -3521,9 +3521,6 @@ static void gen_sse(CPUX86State *env, DisasContext *s,
int b,
case 0x171: /* shift xmm, im */
case 0x172:
case 0x173:
- if (b1 >= 2) {
- goto unknown_op;
- }
val = x86_ldub_code(env, s);
if (is_xmm) {
tcg_gen_movi_tl(s->T0, val);
@@ -3772,9 +3769,6 @@ static void gen_sse(CPUX86State *env, DisasContext *s,
int b,
rm = modrm & 7;
reg = ((modrm >> 3) & 7) | REX_R(s);
mod = (modrm >> 6) & 3;
- if (b1 >= 2) {
- goto unknown_op;
- }
sse_fn_epp = sse_op_table6[b].op[b1];
if (!sse_fn_epp) {
@@ -4202,9 +4196,6 @@ static void gen_sse(CPUX86State *env, DisasContext *s,
int b,
rm = modrm & 7;
reg = ((modrm >> 3) & 7) | REX_R(s);
mod = (modrm >> 6) & 3;
- if (b1 >= 2) {
- goto unknown_op;
- }
sse_fn_eppi = sse_op_table7[b].op[b1];
if (!sse_fn_eppi) {
--
2.20.1
- [PATCH] target/i386: Remove unnecessary checks of b2 in SSE decode,
Peter Maydell <=