This is a regression present on mainline and 4.7 branch for targets using SJLJ
exceptions by default in Ada (e.g. ARM). The error message is:
+===========================GNAT BUG DETECTED==============================+
| 4.8.0 20120716 (experimental) [trunk revision 189525] (x86_64-suse-linux) GCC
error:|
| in set_lattice_value, at tree-ssa-ccp.c:452 |
| Error detected around p.adb:16:4
It's valid_lattice_transition returning false on a transition from INTEGER_CST
to a constant &x. It occurs for an array reference with non-constant index: on
the first round, &x + i is non-constant so the algorithm computes an alignment
factor which is an INTEGER_CST; on the second round, i is 0 so the new value is
the constant &x.
valid_lattice_transition accepts the reverse transition. The attached patch
makes the function accept this transition as well.
Tested on x86_64-suse-linux, OK for the mainline and 4.7 branch?
2012-07-18 Eric Botcazou <[email protected]>
* tree-ssa-ccp.c (valid_lattice_transition): Allow transitioning from
as well as to INTEGER_CST.
2012-07-18 Eric Botcazou <[email protected]>
* gnat.dg/loop_optimization11.adb: New test.
* gnat.dg/loop_optimization11_pkg.ads: New helper.
--
Eric Botcazou
Index: tree-ssa-ccp.c
===================================================================
--- tree-ssa-ccp.c (revision 189525)
+++ tree-ssa-ccp.c (working copy)
@@ -405,9 +405,9 @@ valid_lattice_transition (prop_value_t o
/* Now both lattice values are CONSTANT. */
- /* Allow transitioning from &x to &x & ~3. */
- if (TREE_CODE (old_val.value) != INTEGER_CST
- && TREE_CODE (new_val.value) == INTEGER_CST)
+ /* Allow transitioning from &x to &x & ~3 and vice versa. */
+ if ((TREE_CODE (old_val.value) == INTEGER_CST)
+ != (TREE_CODE (new_val.value) == INTEGER_CST))
return true;
/* Bit-lattices have to agree in the still valid bits. */
-- { dg-do compile }
-- { dg-options "-O" }
with Loop_Optimization11_Pkg; use Loop_Optimization11_Pkg;
procedure Loop_Optimization11 is
Arr : array (Prot, Mem) of Integer := (others => (others => 0));
begin
Put_Line (Img (0) & " ");
for I in Arr'Range (1) loop
for J in Arr'Range (2) loop
declare
Elem : Integer renames Arr (I, J);
begin
Put_Line (Img (Elem));
end;
end loop;
end loop;
end;
package Loop_Optimization11_Pkg is
function Img (X : Integer) return String;
procedure Put_Line (Data : String);
type Prot is (Execute, Execute_Read, Execute_Read_Write);
type Mem is (Mem_Image, Mem_Mapped, Mem_Private, Unknown);
end Loop_Optimization11_Pkg;
