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tcg/optimize: Remember garbage high bits for 32-bit ops 

For a 64-bit host, the high bits of a register after a 32-bit operation
are undefined.  Adjust the temps mask for all 32-bit ops to reflect that.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2014-05-22 11:14:10 -07:00
parent a62f6f5600
commit 24666baf1f
1 changed files with 26 additions and 7 deletions
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33
tcg/optimize.c
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@ -166,11 +166,18 @@ static void tcg_opt_gen_mov(TCGContext *s, int op_index, TCGArg *gen_args,
TCGOpcode old_op, TCGArg dst, TCGArg src)
{
TCGOpcode new_op = op_to_mov(old_op);
tcg_target_ulong mask;
s->gen_opc_buf[op_index] = new_op;
reset_temp(dst);
temps[dst].mask = temps[src].mask;
mask = temps[src].mask;
if (TCG_TARGET_REG_BITS > 32 && new_op == INDEX_op_mov_i32) {
/* High bits of the destination are now garbage. */
mask |= ~0xffffffffull;
}
temps[dst].mask = mask;
assert(temps[src].state != TCG_TEMP_CONST);
if (s->temps[src].type == s->temps[dst].type) {
@ -194,13 +201,20 @@ static void tcg_opt_gen_movi(TCGContext *s, int op_index, TCGArg *gen_args,
TCGOpcode old_op, TCGArg dst, TCGArg val)
{
TCGOpcode new_op = op_to_movi(old_op);
tcg_target_ulong mask;
s->gen_opc_buf[op_index] = new_op;
reset_temp(dst);
temps[dst].state = TCG_TEMP_CONST;
temps[dst].val = val;
temps[dst].mask = val;
mask = val;
if (TCG_TARGET_REG_BITS > 32 && new_op == INDEX_op_mov_i32) {
/* High bits of the destination are now garbage. */
mask |= ~0xffffffffull;
}
temps[dst].mask = mask;
gen_args[0] = dst;
gen_args[1] = val;
}
@ -539,7 +553,7 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
for (op_index = 0; op_index < nb_ops; op_index++) {
TCGOpcode op = s->gen_opc_buf[op_index];
const TCGOpDef *def = &tcg_op_defs[op];
tcg_target_ulong mask, affected;
tcg_target_ulong mask, partmask, affected;
int nb_oargs, nb_iargs, nb_args, i;
TCGArg tmp;
@ -902,13 +916,18 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
break;
}
/* 32-bit ops (non 64-bit ops and non load/store ops) generate 32-bit
results */
/* 32-bit ops (non 64-bit ops and non load/store ops) generate
32-bit results. For the result is zero test below, we can
ignore high bits, but for further optimizations we need to
record that the high bits contain garbage. */
partmask = mask;
if (!(def->flags & (TCG_OPF_CALL_CLOBBER | TCG_OPF_64BIT))) {
mask &= 0xffffffffu;
mask |= ~(tcg_target_ulong)0xffffffffu;
partmask &= 0xffffffffu;
affected &= 0xffffffffu;
}
if (mask == 0) {
if (partmask == 0) {
assert(nb_oargs == 1);
tcg_opt_gen_movi(s, op_index, gen_args, op, args[0], 0);
args += nb_args;