This patch is the second of two changes to genmatch that don't affect
the executable code, but reduce the amount of debugging information
generated in stage3 of a build, but adhering more closely to GNU style
guidelines.
This patch avoids generating "next_after_fail1:;" label statements
in genmatch, if this label is unused/never referenced as the target
of a goto. Because jumps to these labels are always forwards, we
know at the point the label is emitted whether it is used or not.
Because a debugger may set a breakpoint these labels, this increase
the size of g{imple,eneric}-match.o in a stage3 build. To save a
little extra space, I also shorten the label to "Lfail1:;" and only
increment the counter when necessary. This reduces the size of
gimple-match.o by 58K on x86_64-pc-linux-gnu.
This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
and make -k check with no new failures. Ok for mainline?
2022-03-16 Roger Sayle <ro...@nextmovesoftware.com>
gcc/ChangeLog
* gcc/genmatch.cc (fail_label_used): New global variable.
(expr::gen_transform): Set fail_label_used whenever a goto
FAIL_LABEL is generated.
(dt_simplify::gen_1): Clear fail_label_used when generating
a new (provisional) fail_label. Set fail_label used whenever
a goto fail_label is generated. Avoid emitting fail_label:
if fail_label_used is false, instead decrement fail_label_cnt.
Thanks in advance,
Roger
--
diff --git a/gcc/genmatch.cc b/gcc/genmatch.cc
index 2eda730..4a61f4e 100644
--- a/gcc/genmatch.cc
+++ b/gcc/genmatch.cc
@@ -2356,6 +2356,8 @@ capture_info::walk_c_expr (c_expr *e)
/* The current label failing the current matched pattern during
code generation. */
static char *fail_label;
+/* Record that a reference/goto to the above label been generated. */
+static bool fail_label_used;
/* Code generation off the decision tree and the refered AST nodes. */
@@ -2533,6 +2535,7 @@ expr::gen_transform (FILE *f, int indent, const char
*dest, bool gimple,
fprintf_indent (f, indent,
"if (!_r%d) goto %s;\n",
depth, fail_label);
+ fail_label_used = true;
if (*opr == CONVERT_EXPR)
{
indent -= 4;
@@ -2560,13 +2563,15 @@ expr::gen_transform (FILE *f, int indent, const char
*dest, bool gimple,
fprintf (f, ");\n");
if (opr->kind != id_base::CODE)
{
- fprintf_indent (f, indent, "if (!_r%d)\n", depth);
- fprintf_indent (f, indent, " goto %s;\n", fail_label);
+ fprintf_indent (f, indent, "if (!_r%d) goto %s;\n",
+ depth, fail_label);
+ fail_label_used = true;
}
if (force_leaf)
{
fprintf_indent (f, indent, "if (EXPR_P (_r%d))\n", depth);
fprintf_indent (f, indent, " goto %s;\n", fail_label);
+ fail_label_used = true;
}
if (*opr == CONVERT_EXPR)
{
@@ -3285,8 +3290,9 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple,
operand *result)
static unsigned fail_label_cnt;
char local_fail_label[256];
- snprintf (local_fail_label, 256, "next_after_fail%u", ++fail_label_cnt);
+ snprintf (local_fail_label, 256, "Lfail%u", ++fail_label_cnt);
fail_label = local_fail_label;
+ fail_label_used = false;
/* Analyze captures and perform early-outs on the incoming arguments
that cover cases we cannot handle. */
@@ -3301,6 +3307,7 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple,
operand *result)
fprintf_indent (f, indent,
"if (TREE_SIDE_EFFECTS (_p%d)) goto %s;\n",
i, fail_label);
+ fail_label_used = true;
if (verbose >= 1)
warning_at (as_a <expr *> (s->match)->ops[i]->location,
"forcing toplevel operand to have no "
@@ -3316,6 +3323,7 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple,
operand *result)
fprintf_indent (f, indent,
"if (TREE_SIDE_EFFECTS (captures[%d])) "
"goto %s;\n", i, fail_label);
+ fail_label_used = true;
if (verbose >= 1)
warning_at (cinfo.info[i].c->location,
"forcing captured operand to have no "
@@ -3358,7 +3366,12 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple,
operand *result)
}
if (s->kind == simplify::SIMPLIFY)
- fprintf_indent (f, indent, "if (__builtin_expect (!dbg_cnt (match), 0))
goto %s;\n", fail_label);
+ {
+ fprintf_indent (f, indent,
+ "if (__builtin_expect (!dbg_cnt (match), 0)) goto %s;\n",
+ fail_label);
+ fail_label_used = true;
+ }
fprintf_indent (f, indent, "if (__builtin_expect (dump_file && (dump_flags &
TDF_FOLDING), 0)) "
"fprintf (dump_file, \"%s ",
@@ -3430,9 +3443,12 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple,
operand *result)
fprintf_indent (f, indent,
"res_op->resimplify (lseq, valueize);\n");
if (e->force_leaf)
- fprintf_indent (f, indent,
- "if (!maybe_push_res_to_seq (res_op, NULL)) "
- "goto %s;\n", fail_label);
+ {
+ fprintf_indent (f, indent,
+ "if (!maybe_push_res_to_seq (res_op, NULL))"
+ " goto %s;\n", fail_label);
+ fail_label_used = true;
+ }
}
}
else if (result->type == operand::OP_CAPTURE
@@ -3488,9 +3504,12 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple,
operand *result)
continue;
if (cinfo.info[i].result_use_count
> cinfo.info[i].match_use_count)
- fprintf_indent (f, indent,
- "if (! tree_invariant_p (captures[%d])) "
- "goto %s;\n", i, fail_label);
+ {
+ fprintf_indent (f, indent,
+ "if (! tree_invariant_p (captures[%d]))"
+ " goto %s;\n", i, fail_label);
+ fail_label_used = true;
+ }
}
for (unsigned j = 0; j < e->ops.length (); ++j)
{
@@ -3539,8 +3558,9 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple,
operand *result)
fprintf (f, ");\n");
if (!is_a <operator_id *> (opr))
{
- fprintf_indent (f, indent, "if (!_r)\n");
- fprintf_indent (f, indent, " goto %s;\n", fail_label);
+ fprintf_indent (f, indent, "if (!_r) goto %s;\n",
+ fail_label);
+ fail_label_used = true;
}
}
}
@@ -3581,7 +3601,10 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple,
operand *result)
}
indent -= 2;
fprintf_indent (f, indent, "}\n");
- fprintf (f, "%s:;\n", fail_label);
+ if (fail_label_used)
+ fprintf (f, "%s:;\n", fail_label);
+ else
+ fail_label_cnt--;
fail_label = NULL;
}
