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tcg/optimize: Split out fold_mb, fold_qemu_{ld,st}

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This puts the separate mb optimization into the same framework
as the others.  While fold_qemu_{ld,st} are currently identical,
that won't last as more code gets moved.

Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2021-08-25 11:06:43 -07:00
parent 404a148d89
commit 3eefdf2b58
1 changed files with 51 additions and 38 deletions
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89
tcg/optimize.c
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@ -692,6 +692,44 @@ static bool fold_call(OptContext *ctx, TCGOp *op)
return true; return true;
} }
static bool fold_mb(OptContext *ctx, TCGOp *op)
{
/* Eliminate duplicate and redundant fence instructions. */
if (ctx->prev_mb) {
/*
* Merge two barriers of the same type into one,
* or a weaker barrier into a stronger one,
* or two weaker barriers into a stronger one.
* mb X; mb Y => mb X|Y
* mb; strl => mb; st
* ldaq; mb => ld; mb
* ldaq; strl => ld; mb; st
* Other combinations are also merged into a strong
* barrier. This is stricter than specified but for
* the purposes of TCG is better than not optimizing.
*/
ctx->prev_mb->args[0] |= op->args[0];
tcg_op_remove(ctx->tcg, op);
} else {
ctx->prev_mb = op;
}
return true;
}
static bool fold_qemu_ld(OptContext *ctx, TCGOp *op)
{
/* Opcodes that touch guest memory stop the mb optimization. */
ctx->prev_mb = NULL;
return false;
}
static bool fold_qemu_st(OptContext *ctx, TCGOp *op)
{
/* Opcodes that touch guest memory stop the mb optimization. */
ctx->prev_mb = NULL;
return false;
}
/* Propagate constants and copies, fold constant expressions. */ /* Propagate constants and copies, fold constant expressions. */
void tcg_optimize(TCGContext *s) void tcg_optimize(TCGContext *s)
{ {
@ -1599,6 +1637,19 @@ void tcg_optimize(TCGContext *s)
} }
break; break;
case INDEX_op_mb:
done = fold_mb(&ctx, op);
break;
case INDEX_op_qemu_ld_i32:
case INDEX_op_qemu_ld_i64:
done = fold_qemu_ld(&ctx, op);
break;
case INDEX_op_qemu_st_i32:
case INDEX_op_qemu_st8_i32:
case INDEX_op_qemu_st_i64:
done = fold_qemu_st(&ctx, op);
break;
default: default:
break; break;
} }
@ -1606,43 +1657,5 @@ void tcg_optimize(TCGContext *s)
if (!done) { if (!done) {
finish_folding(&ctx, op); finish_folding(&ctx, op);
} }
/* Eliminate duplicate and redundant fence instructions. */
if (ctx.prev_mb) {
switch (opc) {
case INDEX_op_mb:
/* Merge two barriers of the same type into one,
* or a weaker barrier into a stronger one,
* or two weaker barriers into a stronger one.
* mb X; mb Y => mb X|Y
* mb; strl => mb; st
* ldaq; mb => ld; mb
* ldaq; strl => ld; mb; st
* Other combinations are also merged into a strong
* barrier. This is stricter than specified but for
* the purposes of TCG is better than not optimizing.
*/
ctx.prev_mb->args[0] |= op->args[0];
tcg_op_remove(s, op);
break;
default:
/* Opcodes that end the block stop the optimization. */
if ((def->flags & TCG_OPF_BB_END) == 0) {
break;
}
/* fallthru */
case INDEX_op_qemu_ld_i32:
case INDEX_op_qemu_ld_i64:
case INDEX_op_qemu_st_i32:
case INDEX_op_qemu_st8_i32:
case INDEX_op_qemu_st_i64:
/* Opcodes that touch guest memory stop the optimization. */
ctx.prev_mb = NULL;
break;
}
} else if (opc == INDEX_op_mb) {
ctx.prev_mb = op;
}
} }
} }