/* SSA Jump Threading
- Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
+ Copyright (C) 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
Contributed by Jeff Law <law@redhat.com>
This file is part of GCC.
#include "timevar.h"
#include "tree-dump.h"
#include "tree-flow.h"
-#include "domwalk.h"
#include "real.h"
#include "tree-pass.h"
#include "tree-ssa-propagate.h"
to copy as part of the jump threading process. */
static int stmt_count;
+/* Array to record value-handles per SSA_NAME. */
+VEC(tree,heap) *ssa_name_values;
+
+/* Set the value for the SSA name NAME to VALUE. */
+
+void
+set_ssa_name_value (tree name, tree value)
+{
+ if (SSA_NAME_VERSION (name) >= VEC_length (tree, ssa_name_values))
+ VEC_safe_grow_cleared (tree, heap, ssa_name_values,
+ SSA_NAME_VERSION (name) + 1);
+ VEC_replace (tree, ssa_name_values, SSA_NAME_VERSION (name), value);
+}
+
+/* Initialize the per SSA_NAME value-handles array. Returns it. */
+void
+threadedge_initialize_values (void)
+{
+ gcc_assert (ssa_name_values == NULL);
+ ssa_name_values = VEC_alloc(tree, heap, num_ssa_names);
+}
+
+/* Free the per SSA_NAME value-handle array. */
+void
+threadedge_finalize_values (void)
+{
+ VEC_free(tree, heap, ssa_name_values);
+}
+
/* Return TRUE if we may be able to thread an incoming edge into
BB to an outgoing edge from BB. Return FALSE otherwise. */
break;
prev_value = VEC_pop (tree, *stack);
- SSA_NAME_VALUE (dest) = prev_value;
+ set_ssa_name_value (dest, prev_value);
}
}
y = tmp ? tmp : y;
}
- SSA_NAME_VALUE (x) = y;
+ set_ssa_name_value (x, y);
VEC_reserve (tree, heap, *stack, 2);
VEC_quick_push (tree, *stack, prev_x);
VEC_quick_push (tree, *stack, x);
}
/* Record temporary equivalences created by PHIs at the target of the
- edge E. Record unwind information for the equivalences onto STACK.
+ edge E. Record unwind information for the equivalences onto STACK.
If a PHI which prevents threading is encountered, then return FALSE
indicating we should not thread this edge, else return TRUE. */
tree src = PHI_ARG_DEF_FROM_EDGE (phi, e);
tree dst = gimple_phi_result (phi);
- /* If the desired argument is not the same as this PHI's result
+ /* If the desired argument is not the same as this PHI's result
and it is set by a PHI in E->dest, then we can not thread
through E->dest. */
if (src != dst
Record unwind information for temporary equivalences onto STACK.
Use SIMPLIFY (a pointer to a callback function) to further simplify
- statements using pass specific information.
+ statements using pass specific information.
We might consider marking just those statements which ultimately
feed the COND_EXPR. It's not clear if the overhead of bookkeeping
stmt = gsi_stmt (gsi);
/* Ignore empty statements and labels. */
- if (gimple_code (stmt) == GIMPLE_NOP || gimple_code (stmt) == GIMPLE_LABEL)
+ if (gimple_code (stmt) == GIMPLE_NOP
+ || gimple_code (stmt) == GIMPLE_LABEL
+ || is_gimple_debug (stmt))
continue;
/* If the statement has volatile operands, then we assume we
The result of __builtin_object_size is defined to be the maximum of
remaining bytes. If we use only one edge on the phi, the result will
- change to be the remaining bytes for the corresponding phi argument. */
+ change to be the remaining bytes for the corresponding phi argument.
+
+ Similarly for __builtin_constant_p:
+
+ r = PHI <1(2), 2(3)>
+ __builtin_constant_p (r)
+
+ Both PHI arguments are constant, but x ? 1 : 2 is still not
+ constant. */
if (is_gimple_call (stmt))
{
tree fndecl = gimple_call_fndecl (stmt);
- if (fndecl && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_OBJECT_SIZE)
+ if (fndecl
+ && (DECL_FUNCTION_CODE (fndecl) == BUILT_IN_OBJECT_SIZE
+ || DECL_FUNCTION_CODE (fndecl) == BUILT_IN_CONSTANT_P))
continue;
}
/* At this point we have a statement which assigns an RHS to an
SSA_VAR on the LHS. We want to try and simplify this statement
to expose more context sensitive equivalences which in turn may
- allow us to simplify the condition at the end of the loop.
+ allow us to simplify the condition at the end of the loop.
Handle simple copy operations as well as implied copies from
ASSERT_EXPRs. */
|| (TREE_CODE (cached_lhs) != SSA_NAME
&& !is_gimple_min_invariant (cached_lhs)))
cached_lhs = (*simplify) (stmt, stmt);
-
+
/* Restore the statement's original uses/defs. */
i = 0;
FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
}
/* We are exiting E->src, see if E->dest ends with a conditional
- jump which has a known value when reached via E.
+ jump which has a known value when reached via E.
Special care is necessary if E is a back edge in the CFG as we
may have already recorded equivalences for E->dest into our
end with a conditional which is either always true or always
false when reached via the loop backedge. Thus we do not want
to blindly disable threading across a loop backedge.
-
+
DUMMY_COND is a shared cond_expr used by condition simplification as scratch,
to avoid allocating memory.
-
+
HANDLE_DOMINATING_ASSERTS is true if we should try to replace operands of
the simplified condition with left-hand sides of ASSERT_EXPRs they are
used in.
-
+
STACK is used to undo temporary equivalences created during the walk of
E->dest.
goto fail;
}
}
-
+
stmt_count = 0;
/* PHIs create temporary equivalences. */
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