middle-end: convert negate + right shift into compare greater.
This turns an inversion of the sign bit + arithmetic right shift into a
comparison with 0.
i.e.
void fun1(int32_t *x, int n)
{
for (int i = 0; i < (n & -16); i++)
x[i] = (-x[i]) >> 31;
}
now generates:
.L3:
ldr q0, [x0]
cmgt v0.4s, v0.4s, #0
str q0, [x0], 16
cmp x0, x1
bne .L3
instead of:
.L3:
ldr q0, [x0]
neg v0.4s, v0.4s
sshr v0.4s, v0.4s, 31
str q0, [x0], 16
cmp x0, x1
bne .L3
gcc/ChangeLog:
* match.pd: New negate+shift pattern.
gcc/testsuite/ChangeLog:
* gcc.dg/signbit-2.c: New test.
* gcc.dg/signbit-3.c: New test.
* gcc.dg/signbit-4.c: New test.
* gcc.dg/signbit-5.c: New test.
* gcc.dg/signbit-6.c: New test.
* gcc.target/aarch64/signbit-1.c: New test.
This commit is contained in:
Tamar Christina
parent
004afb984b
commit
d70720c238
36
gcc/match.pd
36
gcc/match.pd
@ -37,7 +37,8 @@ along with GCC; see the file COPYING3. If not see
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integer_pow2p
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uniform_integer_cst_p
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HONOR_NANS
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uniform_vector_p)
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uniform_vector_p
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expand_vec_cmp_expr_p)
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/* Operator lists. */
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(define_operator_list tcc_comparison
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@ -831,6 +832,39 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
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{ tree utype = unsigned_type_for (type); }
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(convert (rshift (lshift (convert:utype @0) @2) @3))))))
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/* Fold (-x >> C) into -(x > 0) where C = precision(type) - 1. */
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(for cst (INTEGER_CST VECTOR_CST)
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(simplify
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(rshift (negate:s @0) cst@1)
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(if (!TYPE_UNSIGNED (type)
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&& TYPE_OVERFLOW_UNDEFINED (type))
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(with { tree stype = TREE_TYPE (@1);
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tree bt = truth_type_for (type);
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tree zeros = build_zero_cst (type);
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tree cst = NULL_TREE; }
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(switch
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/* Handle scalar case. */
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(if (INTEGRAL_TYPE_P (type)
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/* If we apply the rule to the scalar type before vectorization
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we will enforce the result of the comparison being a bool
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which will require an extra AND on the result that will be
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indistinguishable from when the user did actually want 0
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or 1 as the result so it can't be removed. */
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&& canonicalize_math_after_vectorization_p ()
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&& wi::eq_p (wi::to_wide (@1), TYPE_PRECISION (type) - 1))
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(negate (convert (gt @0 { zeros; }))))
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/* Handle vector case. */
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(if (VECTOR_INTEGER_TYPE_P (type)
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/* First check whether the target has the same mode for vector
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comparison results as it's operands do. */
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&& TYPE_MODE (bt) == TYPE_MODE (type)
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/* Then check to see if the target is able to expand the comparison
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with the given type later on, otherwise we may ICE. */
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&& expand_vec_cmp_expr_p (type, bt, GT_EXPR)
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&& (cst = uniform_integer_cst_p (@1)) != NULL
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&& wi::eq_p (wi::to_wide (cst), element_precision (type) - 1))
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(view_convert (gt:bt @0 { zeros; }))))))))
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/* Fold (C1/X)*C2 into (C1*C2)/X. */
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(simplify
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(mult (rdiv@3 REAL_CST@0 @1) REAL_CST@2)
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19
gcc/testsuite/gcc.dg/signbit-2.c
Normal file
19
gcc/testsuite/gcc.dg/signbit-2.c
Normal file
@ -0,0 +1,19 @@
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/* { dg-do assemble } */
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/* { dg-options "-O3 --save-temps -fdump-tree-optimized" } */
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#include <stdint.h>
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void fun1(int32_t *x, int n)
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{
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for (int i = 0; i < (n & -16); i++)
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x[i] = (-x[i]) >> 31;
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}
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void fun2(int32_t *x, int n)
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{
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for (int i = 0; i < (n & -16); i++)
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x[i] = (-x[i]) >> 30;
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}
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/* { dg-final { scan-tree-dump-times {\s+>\s+\{ 0, 0, 0, 0 \}} 1 optimized } } */
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/* { dg-final { scan-tree-dump-not {\s+>>\s+31} optimized } } */
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13
gcc/testsuite/gcc.dg/signbit-3.c
Normal file
13
gcc/testsuite/gcc.dg/signbit-3.c
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@ -0,0 +1,13 @@
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/* { dg-do assemble } */
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/* { dg-options "-O1 --save-temps -fdump-tree-optimized" } */
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#include <stdint.h>
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void fun1(int32_t *x, int n)
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{
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for (int i = 0; i < (n & -16); i++)
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x[i] = (-x[i]) >> 31;
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}
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/* { dg-final { scan-tree-dump-times {\s+>\s+0;} 1 optimized } } */
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/* { dg-final { scan-tree-dump-not {\s+>>\s+31} optimized } } */
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65
gcc/testsuite/gcc.dg/signbit-4.c
Normal file
65
gcc/testsuite/gcc.dg/signbit-4.c
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@ -0,0 +1,65 @@
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/* { dg-do run } */
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/* { dg-options "-O1 -fwrapv" } */
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#include <stdint.h>
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#include <limits.h>
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#include <stdio.h>
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#ifndef N
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#define N 65
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#endif
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#ifndef TYPE
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#define TYPE int32_t
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#endif
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#ifndef DEBUG
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#define DEBUG 1
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#endif
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#define BASE ((TYPE) -1 < 0 ? -126 : 4)
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__attribute__ ((noinline, noipa))
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void fun1(TYPE *x, int n)
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{
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for (int i = 0; i < n; i++)
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x[i] = (-x[i]) >> 31;
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}
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__attribute__ ((noinline, noipa, optimize("O0")))
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void fun2(TYPE *x, int n)
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{
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for (int i = 0; i < n; i++)
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x[i] = (-x[i]) >> 31;
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}
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int main ()
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{
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TYPE a[N];
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TYPE b[N];
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a[0] = INT_MIN;
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b[0] = INT_MIN;
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for (int i = 1; i < N; ++i)
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{
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a[i] = BASE + i * 13;
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b[i] = BASE + i * 13;
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if (DEBUG)
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printf ("%d: 0x%x\n", i, a[i]);
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}
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fun1 (a, N);
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fun2 (b, N);
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for (int i = 0; i < N; ++i)
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{
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if (DEBUG)
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printf ("%d = 0x%x == 0x%x\n", i, a[i], b[i]);
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if (a[i] != b[i])
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__builtin_abort ();
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}
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return 0;
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}
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65
gcc/testsuite/gcc.dg/signbit-5.c
Normal file
65
gcc/testsuite/gcc.dg/signbit-5.c
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@ -0,0 +1,65 @@
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/* { dg-do run } */
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/* { dg-options "-O3" } */
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#include <stdint.h>
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#include <limits.h>
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#include <stdio.h>
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#ifndef N
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#define N 65
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#endif
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#ifndef TYPE
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#define TYPE int32_t
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#endif
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#ifndef DEBUG
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#define DEBUG 1
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#endif
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#define BASE ((TYPE) -1 < 0 ? -126 : 4)
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__attribute__ ((noinline, noipa))
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void fun1(TYPE *x, int n)
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{
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for (int i = 0; i < n; i++)
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x[i] = (-x[i]) >> 31;
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}
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__attribute__ ((noinline, noipa, optimize("O1")))
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void fun2(TYPE *x, int n)
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{
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for (int i = 0; i < n; i++)
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x[i] = (-x[i]) >> 31;
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}
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int main ()
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{
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TYPE a[N];
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TYPE b[N];
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a[0] = INT_MIN;
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b[0] = INT_MIN;
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for (int i = 1; i < N; ++i)
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{
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a[i] = BASE + i * 13;
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b[i] = BASE + i * 13;
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if (DEBUG)
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printf ("%d: 0x%x\n", i, a[i]);
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}
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fun1 (a, N);
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fun2 (b, N);
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for (int i = 0; i < N; ++i)
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{
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if (DEBUG)
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printf ("%d = 0x%x == 0x%x\n", i, a[i], b[i]);
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if (a[i] != b[i])
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__builtin_abort ();
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}
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return 0;
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}
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72
gcc/testsuite/gcc.dg/signbit-6.c
Normal file
72
gcc/testsuite/gcc.dg/signbit-6.c
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@ -0,0 +1,72 @@
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/* { dg-do run } */
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/* { dg-options "-O1" } */
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#include <stdint.h>
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#include <limits.h>
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#include <stdio.h>
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#ifndef N
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#define N 65
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#endif
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#ifndef TYPE
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#define TYPE int32_t
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#endif
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#ifndef DEBUG
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#define DEBUG 1
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#endif
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#define BASE ((TYPE) -1 < 0 ? -126 : 4)
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__attribute__ ((noinline, noipa))
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void fun1(TYPE *x, int n)
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{
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for (int i = 0; i < n; i++)
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x[i] = (-x[i]) >> 31;
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}
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__attribute__ ((noinline, noipa, optimize("O0")))
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void fun2(TYPE *x, int n)
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{
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for (int i = 0; i < n; i++)
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x[i] = (-x[i]) >> 31;
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}
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int main ()
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{
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TYPE a[N];
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TYPE b[N];
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a[0] = INT_MIN;
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b[0] = INT_MIN;
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for (int i = 1; i < N; ++i)
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{
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a[i] = BASE + i * 13;
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b[i] = BASE + i * 13;
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if (DEBUG)
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printf ("%d: 0x%x\n", i, a[i]);
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}
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fun1 (a, N);
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fun2 (b, N);
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if (DEBUG)
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printf ("%d = 0x%x == 0x%x\n", 0, a[0], b[0]);
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if (a[0] != 0x0 || b[0] != -1)
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__builtin_abort ();
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for (int i = 1; i < N; ++i)
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{
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if (DEBUG)
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printf ("%d = 0x%x == 0x%x\n", i, a[i], b[i]);
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if (a[i] != b[i])
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__builtin_abort ();
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}
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return 0;
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}
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20
gcc/testsuite/gcc.target/aarch64/signbit-1.c
Normal file
20
gcc/testsuite/gcc.target/aarch64/signbit-1.c
Normal file
@ -0,0 +1,20 @@
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/* { dg-do assemble } */
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/* { dg-options "-O3 --save-temps" } */
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#include <stdint.h>
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#pragma GCC target "+nosve"
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void fun1(int32_t *x, int n)
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{
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for (int i = 0; i < (n & -16); i++)
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x[i] = (-x[i]) >> 31;
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}
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void fun2(int32_t *x, int n)
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{
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for (int i = 0; i < (n & -16); i++)
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x[i] = (-x[i]) >> 30;
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}
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/* { dg-final { scan-assembler-times {\tcmgt\t} 1 } } */
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