params.def (PARAM_MAX_VARTRACK_EXPR_DEPTH): New.

* params.def (PARAM_MAX_VARTRACK_EXPR_DEPTH): New.
* doc/invoke.texi: Document max-vartrack-expr-depth.
* var-tracking.c (EXPR_DEPTH): New.
(reverse_op, vt_expand_loc, vt_expand_loc_dummy): Use it.

From-SVN: r174494

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e4aa907408178259ea4dfe9edbe4d3a866624f3a..e1e32af417c4be0317b4f911adbc0dd4184c3d2d 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2011-05-31  Alexandre Oliva  <aoliva@redhat.com>
+
+       * params.def (PARAM_MAX_VARTRACK_EXPR_DEPTH): New.
+       * doc/invoke.texi: Document max-vartrack-expr-depth.
+       * var-tracking.c (EXPR_DEPTH): New.
+       (reverse_op, vt_expand_loc, vt_expand_loc_dummy): Use it.
+
 2011-05-31  Alexandre Oliva  <aoliva@redhat.com>
 
        * config/i386/i386.c (ix86_rtx_costs): Drop NEG from sub for FMA.

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 4b54c4abdaeb2d293bab1039a3e3515c22b59a00..20ee33bb16a72e0cca24e992c648db83db6b2f91 100644 (file)
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -8940,6 +8940,16 @@ the function.  If the limit is exceeded even without debug insns, var
 tracking analysis is completely disabled for the function.  Setting
 the parameter to zero makes it unlimited.
 
+@item max-vartrack-expr-depth
+Sets a maximum number of recursion levels when attempting to map
+variable names or debug temporaries to value expressions.  This trades
+compile time for more complete debug information.  If this is set too
+low, value expressions that are available and could be represented in
+debug information may end up not being used; setting this higher may
+enable the compiler to find more complex debug expressions, but compile
+time may grow exponentially, and even then, it may fail to find more
+usable expressions.  The default is 10.
+
 @item min-nondebug-insn-uid
 Use uids starting at this parameter for nondebug insns.  The range below
 the parameter is reserved exclusively for debug insns created by

diff --git a/gcc/params.def b/gcc/params.def
index fa89a5221ec0990e39ffd5b273479bbe76d1acc1..2ed0acac36c8a228fb7340fa969f2c6bb33ccd4d 100644 (file)
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -839,6 +839,14 @@ DEFPARAM (PARAM_MAX_VARTRACK_SIZE,
          "Max. size of var tracking hash tables",
          50000000, 0, 0)
 
+/* Set maximum recursion depth for var tracking expression expansion
+   and resolution.  */
+
+DEFPARAM (PARAM_MAX_VARTRACK_EXPR_DEPTH,
+         "max-vartrack-expr-depth",
+         "Max. recursion depth for expanding var tracking expressions",
+         10, 0, 0)
+
 /* Set minimum insn uid for non-debug insns.  */
 
 DEFPARAM (PARAM_MIN_NONDEBUG_INSN_UID,

diff --git a/gcc/var-tracking.c b/gcc/var-tracking.c
index 2c16d08e02cb967408c5436d8cd4fb14e9e7b854..488635d7f64a3de6b0ce945f14833eb87f97f922 100644 (file)
--- a/gcc/var-tracking.c
+++ b/gcc/var-tracking.c
@@ -5215,6 +5215,8 @@ add_uses_1 (rtx *x, void *cui)
   for_each_rtx (x, add_uses, cui);
 }
 
+#define EXPR_DEPTH (PARAM_VALUE (PARAM_MAX_VARTRACK_EXPR_DEPTH))
+
 /* Attempt to reverse the EXPR operation in the debug info.  Say for
    reg1 = reg2 + 6 even when reg2 is no longer live we
    can express its value as VAL - 6.  */
@@ -5286,7 +5288,7 @@ reverse_op (rtx val, const_rtx expr)
       arg = XEXP (src, 1);
       if (!CONST_INT_P (arg) && GET_CODE (arg) != SYMBOL_REF)
        {
-         arg = cselib_expand_value_rtx (arg, scratch_regs, 5);
+         arg = cselib_expand_value_rtx (arg, scratch_regs, EXPR_DEPTH);
          if (arg == NULL_RTX)
            return NULL_RTX;
          if (!CONST_INT_P (arg) && GET_CODE (arg) != SYMBOL_REF)
@@ -7416,7 +7418,7 @@ vt_expand_loc (rtx loc, htab_t vars, bool ignore_cur_loc)
   data.dummy = false;
   data.cur_loc_changed = false;
   data.ignore_cur_loc = ignore_cur_loc;
-  loc = cselib_expand_value_rtx_cb (loc, scratch_regs, 8,
+  loc = cselib_expand_value_rtx_cb (loc, scratch_regs, EXPR_DEPTH,
                                    vt_expand_loc_callback, &data);
 
   if (loc && MEM_P (loc))
@@ -7438,7 +7440,7 @@ vt_expand_loc_dummy (rtx loc, htab_t vars, bool *pcur_loc_changed)
   data.dummy = true;
   data.cur_loc_changed = false;
   data.ignore_cur_loc = false;
-  ret = cselib_dummy_expand_value_rtx_cb (loc, scratch_regs, 8,
+  ret = cselib_dummy_expand_value_rtx_cb (loc, scratch_regs, EXPR_DEPTH,
                                          vt_expand_loc_callback, &data);
   *pcur_loc_changed = data.cur_loc_changed;
   return ret;