This fixes a missed optimization in CCP bit-propagation where we
lost the fact of upper zero bits of unsigned VARYING values
(the wide-int conversion made somewhat of a mess of all this).
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2015-10-21 Richard Biener <rguent...@suse.de>
PR tree-optimization/68026
* tree-ssa-ccp.c (get_value_for_expr): Zero-extend mask for
unsigned VARYING values.
* gcc.dg/tree-ssa/ssa-ccp-39.c: New testcase.
Index: gcc/tree-ssa-ccp.c
===================================================================
*** gcc/tree-ssa-ccp.c (revision 229031)
--- gcc/tree-ssa-ccp.c (working copy)
*************** get_value_for_expr (tree expr, bool for_
*** 629,634 ****
--- 629,639 ----
val.mask = -1;
val.value = NULL_TREE;
}
+
+ if (val.lattice_val == VARYING
+ && TYPE_UNSIGNED (TREE_TYPE (expr)))
+ val.mask = wi::zext (val.mask, TYPE_PRECISION (TREE_TYPE (expr)));
+
return val;
}
Index: gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-39.c
===================================================================
*** gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-39.c (revision 0)
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-39.c (working copy)
***************
*** 0 ****
--- 1,19 ----
+ /* { dg-do run } */
+ /* { dg-options "-O -fdump-tree-ccp1" } */
+
+ int main (void)
+ {
+ volatile int x1 = 1;
+ volatile int x2 = 1;
+ int x3 = 2;
+ int t = 1;
+
+ t = 3<=(x2|1|x3|x1-1U);
+
+ if (t == 1) {}
+ else { __builtin_abort(); }
+
+ return 0;
+ }
+
+ /* { dg-final { scan-tree-dump-not "abort" "ccp1" } } */
