match.pd: Add some __builtin_ctz (x) cmp cst simplifications [PR95527]
This patch adds some ctz simplifications (e.g. ctz (x) >= 3 can be done by testing if the low 3 bits are zero, etc.). In addition, I've noticed that in the CLZ case, the #ifdef CLZ_DEFINED_VALUE_AT_ZERO don't really work as intended, they are evaluated during genmatch and the macro is not defined then (but, because of the missing tm.h includes it isn't defined in gimple-match.c or generic-match.c either). And when tm.h is included, defaults.h is included which defines a fallback version of that macro. For GCC 12, I wonder if it wouldn't be better to say in addition to __builtin_c[lt]z* is always UB at zero that it would be undefined for .C[LT]Z ifn too if it has just one operand and use a second operand to be the constant we expect at zero. 2021-04-27 Jakub Jelinek <jakub@redhat.com> PR tree-optimization/95527 * generic-match-head.c: Include tm.h. * gimple-match-head.c: Include tm.h. * match.pd (CLZ == INTEGER_CST): Don't use #ifdef CLZ_DEFINED_VALUE_AT_ZERO, only test CLZ_DEFINED_VALUE_AT_ZERO if clz == CFN_CLZ. Add missing val declaration. (CTZ cmp CST): New simplifications. * gcc.dg/tree-ssa/pr95527-2.c: New test.
This commit is contained in:
Jakub Jelinek
parent
3dcd1334b4
commit
75f8900159
@ -37,6 +37,7 @@ along with GCC; see the file COPYING3. If not see
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#include "gimplify.h"
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#include "optabs-tree.h"
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#include "dbgcnt.h"
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#include "tm.h"
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/* Routine to determine if the types T1 and T2 are effectively
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the same for GENERIC. If T1 or T2 is not a type, the test
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@ -43,6 +43,7 @@ along with GCC; see the file COPYING3. If not see
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#include "optabs-tree.h"
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#include "tree-eh.h"
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#include "dbgcnt.h"
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#include "tm.h"
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/* Forward declarations of the private auto-generated matchers.
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They expect valueized operands in canonical order and do not
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91
gcc/match.pd
91
gcc/match.pd
@ -6341,30 +6341,97 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
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(op (clz:s@2 @0) INTEGER_CST@1)
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(if (integer_zerop (@1) && single_use (@2))
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/* clz(X) == 0 is (int)X < 0 and clz(X) != 0 is (int)X >= 0. */
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(with { tree stype = signed_type_for (TREE_TYPE (@0));
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(with { tree type0 = TREE_TYPE (@0);
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tree stype = signed_type_for (type0);
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HOST_WIDE_INT val = 0;
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#ifdef CLZ_DEFINED_VALUE_AT_ZERO
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/* Punt on hypothetical weird targets. */
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if (CLZ_DEFINED_VALUE_AT_ZERO (TYPE_MODE (TREE_TYPE (@0)),
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val) == 2
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if (clz == CFN_CLZ
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&& CLZ_DEFINED_VALUE_AT_ZERO (SCALAR_TYPE_MODE (type0),
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val) == 2
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&& val == 0)
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stype = NULL_TREE;
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#endif
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}
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(if (stype)
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(cmp (convert:stype @0) { build_zero_cst (stype); })))
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/* clz(X) == (prec-1) is X == 1 and clz(X) != (prec-1) is X != 1. */
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(with { bool ok = true;
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#ifdef CLZ_DEFINED_VALUE_AT_ZERO
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HOST_WIDE_INT val = 0;
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tree type0 = TREE_TYPE (@0);
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/* Punt on hypothetical weird targets. */
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if (CLZ_DEFINED_VALUE_AT_ZERO (TYPE_MODE (TREE_TYPE (@0)),
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val) == 2
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&& val == TYPE_PRECISION (TREE_TYPE (@0)) - 1)
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if (clz == CFN_CLZ
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&& CLZ_DEFINED_VALUE_AT_ZERO (SCALAR_TYPE_MODE (type0),
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val) == 2
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&& val == TYPE_PRECISION (type0) - 1)
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ok = false;
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#endif
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}
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(if (ok && wi::to_wide (@1) == (TYPE_PRECISION (TREE_TYPE (@0)) - 1))
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(op @0 { build_one_cst (TREE_TYPE (@0)); })))))))
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(if (ok && wi::to_wide (@1) == (TYPE_PRECISION (type0) - 1))
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(op @0 { build_one_cst (type0); })))))))
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/* CTZ simplifications. */
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(for ctz (CTZ)
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(for op (ge gt le lt)
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cmp (eq eq ne ne)
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(simplify
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/* __builtin_ctz (x) >= C -> (x & ((1 << C) - 1)) == 0. */
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(op (ctz:s @0) INTEGER_CST@1)
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(with { bool ok = true;
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HOST_WIDE_INT val = 0;
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if (!tree_fits_shwi_p (@1))
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ok = false;
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else
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{
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val = tree_to_shwi (@1);
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/* Canonicalize to >= or <. */
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if (op == GT_EXPR || op == LE_EXPR)
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{
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if (val == HOST_WIDE_INT_MAX)
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ok = false;
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else
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val++;
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}
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}
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bool zero_res = false;
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HOST_WIDE_INT zero_val = 0;
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tree type0 = TREE_TYPE (@0);
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int prec = TYPE_PRECISION (type0);
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if (ctz == CFN_CTZ
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&& CTZ_DEFINED_VALUE_AT_ZERO (SCALAR_TYPE_MODE (type0),
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zero_val) == 2)
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zero_res = true;
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}
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(if (val <= 0)
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(if (ok && (!zero_res || zero_val >= val))
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{ constant_boolean_node (cmp == EQ_EXPR ? true : false, type); })
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(if (val >= prec)
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(if (ok && (!zero_res || zero_val < val))
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{ constant_boolean_node (cmp == EQ_EXPR ? false : true, type); })
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(if (ok && (!zero_res || zero_val < 0 || zero_val >= prec))
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(cmp (bit_and @0 { wide_int_to_tree (type0,
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wi::mask (val, false, prec)); })
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{ build_zero_cst (type0); })))))))
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(for op (eq ne)
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(simplify
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/* __builtin_ctz (x) == C -> (x & ((1 << (C + 1)) - 1)) == (1 << C). */
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(op (ctz:s @0) INTEGER_CST@1)
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(with { bool zero_res = false;
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HOST_WIDE_INT zero_val = 0;
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tree type0 = TREE_TYPE (@0);
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int prec = TYPE_PRECISION (type0);
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if (ctz == CFN_CTZ
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&& CTZ_DEFINED_VALUE_AT_ZERO (SCALAR_TYPE_MODE (type0),
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zero_val) == 2)
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zero_res = true;
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}
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(if (tree_int_cst_sgn (@1) < 0 || wi::to_widest (@1) >= prec)
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(if (!zero_res || zero_val != wi::to_widest (@1))
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{ constant_boolean_node (op == EQ_EXPR ? false : true, type); })
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(if (!zero_res || zero_val < 0 || zero_val >= prec)
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(op (bit_and @0 { wide_int_to_tree (type0,
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wi::mask (tree_to_uhwi (@1) + 1,
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false, prec)); })
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{ wide_int_to_tree (type0,
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wi::shifted_mask (tree_to_uhwi (@1), 1,
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false, prec)); })))))))
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/* POPCOUNT simplifications. */
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/* popcount(X) + popcount(Y) is popcount(X|Y) when X&Y must be zero. */
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57
gcc/testsuite/gcc.dg/tree-ssa/pr95527-2.c
Normal file
57
gcc/testsuite/gcc.dg/tree-ssa/pr95527-2.c
Normal file
@ -0,0 +1,57 @@
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/* PR tree-optimization/95527 */
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/* { dg-do compile } */
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/* { dg-options "-O2 -fdump-tree-original" } */
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/* { dg-final { scan-tree-dump "a & 7\\) == 0" "original" } } */
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/* { dg-final { scan-tree-dump "b & 63\\) != 0" "original" } } */
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/* { dg-final { scan-tree-dump-times "return 0;" 2 "original" } } */
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/* { dg-final { scan-tree-dump-times "return 1;" 2 "original" } } */
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/* { dg-final { scan-tree-dump "g & 15\\) == 8" "original" } } */
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/* { dg-final { scan-tree-dump "h & 255\\) != 128" "original" } } */
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int
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f1 (int a)
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{
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return __builtin_ctz (a) >= 3;
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}
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int
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f2 (int b)
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{
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return __builtin_ctz (b) < 6;
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}
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int
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f3 (int c)
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{
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return __builtin_ctz (c) < 0;
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}
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int
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f4 (int d)
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{
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return __builtin_ctz (d) >= 0;
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}
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int
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f5 (int e)
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{
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return __builtin_ctz (e) >= __SIZEOF_INT__ * __CHAR_BIT__;
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}
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int
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f6 (int f)
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{
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return __builtin_ctz (f) < __SIZEOF_INT__ * __CHAR_BIT__;
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}
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int
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f7 (int g)
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{
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return __builtin_ctz (g) == 3;
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}
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int
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f8 (int h)
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{
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return __builtin_ctz (h) != 7;
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}
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