Hi!
The following testcase is miscompiled (by CCP, or, if -fno-tree-ccp,
by VRP), because the (X & C1) | C2 folding changes the C1 constant
into an integer constant with most significant bit set, but not
sign-extended into the double_int. Fixed by using double_int_to_tree
which extends it properly, instead of build_int_cst_wide.
Instead of creating a double_int from the hi3/lo3 pair I've changed
the code to actually work on double_ints.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2012-02-17 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/52286
* fold-const.c (fold_binary_loc): For (X & C1) | C2
optimization use double_int_to_tree instead of build_int_cst_wide,
rewrite to use double_int vars.
* gcc.c-torture/execute/pr52286.c: New test.
--- gcc/fold-const.c.jj 2012-02-16 20:04:34.000000000 +0100
+++ gcc/fold-const.c 2012-02-17 12:05:46.559700551 +0100
@@ -10959,66 +10959,50 @@ fold_binary_loc (location_t loc,
&& TREE_CODE (arg1) == INTEGER_CST
&& TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST)
{
- unsigned HOST_WIDE_INT hi1, lo1, hi2, lo2, hi3, lo3, mlo, mhi;
+ double_int c1, c2, c3, msk;
int width = TYPE_PRECISION (type), w;
- hi1 = TREE_INT_CST_HIGH (TREE_OPERAND (arg0, 1));
- lo1 = TREE_INT_CST_LOW (TREE_OPERAND (arg0, 1));
- hi2 = TREE_INT_CST_HIGH (arg1);
- lo2 = TREE_INT_CST_LOW (arg1);
+ c1 = tree_to_double_int (TREE_OPERAND (arg0, 1));
+ c2 = tree_to_double_int (arg1);
/* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
- if ((hi1 & hi2) == hi1 && (lo1 & lo2) == lo1)
+ if (double_int_equal_p (double_int_and (c1, c2), c1))
return omit_one_operand_loc (loc, type, arg1,
- TREE_OPERAND (arg0, 0));
+ TREE_OPERAND (arg0, 0));
- if (width > HOST_BITS_PER_WIDE_INT)
- {
- mhi = (unsigned HOST_WIDE_INT) -1
- >> (2 * HOST_BITS_PER_WIDE_INT - width);
- mlo = -1;
- }
- else
- {
- mhi = 0;
- mlo = (unsigned HOST_WIDE_INT) -1
- >> (HOST_BITS_PER_WIDE_INT - width);
- }
+ msk = double_int_mask (width);
/* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
- if ((~(hi1 | hi2) & mhi) == 0 && (~(lo1 | lo2) & mlo) == 0)
+ if (double_int_zero_p (double_int_and_not (msk,
+ double_int_ior (c1, c2))))
return fold_build2_loc (loc, BIT_IOR_EXPR, type,
- TREE_OPERAND (arg0, 0), arg1);
+ TREE_OPERAND (arg0, 0), arg1);
/* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
mode which allows further optimizations. */
- hi1 &= mhi;
- lo1 &= mlo;
- hi2 &= mhi;
- lo2 &= mlo;
- hi3 = hi1 & ~hi2;
- lo3 = lo1 & ~lo2;
+ c1 = double_int_and (c1, msk);
+ c2 = double_int_and (c2, msk);
+ c3 = double_int_and_not (c1, c2);
for (w = BITS_PER_UNIT;
w <= width && w <= HOST_BITS_PER_WIDE_INT;
w <<= 1)
{
unsigned HOST_WIDE_INT mask
= (unsigned HOST_WIDE_INT) -1 >> (HOST_BITS_PER_WIDE_INT - w);
- if (((lo1 | lo2) & mask) == mask
- && (lo1 & ~mask) == 0 && hi1 == 0)
+ if (((c1.low | c2.low) & mask) == mask
+ && (c1.low & ~mask) == 0 && c1.high == 0)
{
- hi3 = 0;
- lo3 = mask;
+ c3 = uhwi_to_double_int (mask);
break;
}
}
- if (hi3 != hi1 || lo3 != lo1)
+ if (!double_int_equal_p (c3, c1))
return fold_build2_loc (loc, BIT_IOR_EXPR, type,
- fold_build2_loc (loc, BIT_AND_EXPR, type,
- TREE_OPERAND (arg0, 0),
- build_int_cst_wide (type,
- lo3, hi3)),
- arg1);
+ fold_build2_loc (loc, BIT_AND_EXPR, type,
+ TREE_OPERAND (arg0, 0),
+ double_int_to_tree (type,
+ c3)),
+ arg1);
}
/* (X & Y) | Y is (X, Y). */
--- gcc/testsuite/gcc.c-torture/execute/pr52286.c.jj 2012-02-17
12:09:41.131621700 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr52286.c 2012-02-17
12:09:22.000000000 +0100
@@ -0,0 +1,14 @@
+/* PR tree-optimization/52286 */
+
+extern void abort (void);
+
+int
+main ()
+{
+ int a, b;
+ asm ("" : "=r" (a) : "0" (0));
+ b = (~a | 1) & -2038094497;
+ if (b >= 0)
+ abort ();
+ return 0;
+}
Jakub
