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[PATCH 28/50] loop-iv.c:replace_single_def_regs
- From: Richard Sandiford <rdsandiford at googlemail dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Sun, 03 Aug 2014 15:13:21 +0100
- Subject: [PATCH 28/50] loop-iv.c:replace_single_def_regs
- Authentication-results: sourceware.org; auth=none
- References: <87y4v5d77q dot fsf at googlemail dot com>
gcc/
* loop-iv.c: Include rtl-iter.h.
(find_single_def_src): New function.
(replace_single_def_regs): Turn from being a for_each_rtx callback
to being a function that examines each subrtx itself.
(replace_in_expr, simplify_using_initial_values): Update accordingly.
Index: gcc/loop-iv.c
===================================================================
--- gcc/loop-iv.c 2014-08-03 11:25:09.905954113 +0100
+++ gcc/loop-iv.c 2014-08-03 11:25:27.978132785 +0100
@@ -62,6 +62,7 @@ Free Software Foundation; either version
#include "df.h"
#include "hash-table.h"
#include "dumpfile.h"
+#include "rtl-iter.h"
/* Possible return values of iv_get_reaching_def. */
@@ -1397,33 +1398,27 @@ simple_rhs_p (rtx rhs)
}
}
-/* If REG has a single definition, replace it with its known value in EXPR.
- Callback for for_each_rtx. */
+/* If REGNO has a single definition, return its known value, otherwise return
+ null. */
-static int
-replace_single_def_regs (rtx *reg, void *expr1)
+static rtx
+find_single_def_src (unsigned int regno)
{
- unsigned regno;
df_ref adef;
rtx set, src;
- rtx *expr = (rtx *)expr1;
- if (!REG_P (*reg))
- return 0;
-
- regno = REGNO (*reg);
for (;;)
{
rtx note;
adef = DF_REG_DEF_CHAIN (regno);
if (adef == NULL || DF_REF_NEXT_REG (adef) != NULL
- || DF_REF_IS_ARTIFICIAL (adef))
- return -1;
+ || DF_REF_IS_ARTIFICIAL (adef))
+ return NULL_RTX;
set = single_set (DF_REF_INSN (adef));
if (set == NULL || !REG_P (SET_DEST (set))
|| REGNO (SET_DEST (set)) != regno)
- return -1;
+ return NULL_RTX;
note = find_reg_equal_equiv_note (DF_REF_INSN (adef));
@@ -1442,10 +1437,29 @@ replace_single_def_regs (rtx *reg, void
break;
}
if (!function_invariant_p (src))
- return -1;
+ return NULL_RTX;
+
+ return src;
+}
+
+/* If any registers in *EXPR that have a single definition, try to replace
+ them with the known-equivalent values. */
- *expr = simplify_replace_rtx (*expr, *reg, src);
- return 1;
+static void
+replace_single_def_regs (rtx *expr)
+{
+ subrtx_var_iterator::array_type array;
+ repeat:
+ FOR_EACH_SUBRTX_VAR (iter, array, *expr, NONCONST)
+ {
+ rtx x = *iter;
+ if (REG_P (x))
+ if (rtx new_x = find_single_def_src (REGNO (x)))
+ {
+ *expr = simplify_replace_rtx (*expr, x, new_x);
+ goto repeat;
+ }
+ }
}
/* A subroutine of simplify_using_initial_values, this function examines INSN
@@ -1490,8 +1504,7 @@ replace_in_expr (rtx *expr, rtx dest, rt
*expr = simplify_replace_rtx (*expr, dest, src);
if (old == *expr)
return;
- while (for_each_rtx (expr, replace_single_def_regs, expr) != 0)
- continue;
+ replace_single_def_regs (expr);
}
/* Checks whether A implies B. */
@@ -1934,9 +1947,7 @@ simplify_using_initial_values (struct lo
gcc_assert (op == UNKNOWN);
- for (;;)
- if (for_each_rtx (expr, replace_single_def_regs, expr) == 0)
- break;
+ replace_single_def_regs (expr);
if (CONSTANT_P (*expr))
return;