630037ede4
Summary: This patch partially implements the `rand` function on the GPU. This is partial because the GPU currently doesn't support thread local storage or static initializers. To implement this on the GPU. I use 1/8th of the local / shared memory quota to treak the shared memory as thread local storage. This is done by simply allocating enough storage for each thread in the block and indexing into this based off of the thread id. The downside to this is that it does not initialize `srand` correctly to be `1` as the standard says, it is also wasteful. In the future we should figure out a way to support TLS on the GPU so that this can be completely common and less resource intensive.
56 lines
1.7 KiB
C++
56 lines
1.7 KiB
C++
//===-- Unittests for rand ------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/stdlib/rand.h"
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#include "src/stdlib/srand.h"
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#include "test/UnitTest/Test.h"
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#include <stddef.h>
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#include <stdlib.h>
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TEST(LlvmLibcRandTest, UnsetSeed) {
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static int vals[1000];
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for (size_t i = 0; i < 1000; ++i) {
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int val = LIBC_NAMESPACE::rand();
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ASSERT_GE(val, 0);
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ASSERT_LE(val, RAND_MAX);
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vals[i] = val;
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}
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// FIXME: The GPU implementation cannot initialize the seed correctly.
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#ifndef LIBC_TARGET_ARCH_IS_GPU
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// The C standard specifies that if 'srand' is never called it should behave
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// as if 'srand' was called with a value of 1. If we seed the value with 1 we
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// should get the same sequence as the unseeded version.
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LIBC_NAMESPACE::srand(1);
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for (size_t i = 0; i < 1000; ++i)
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ASSERT_EQ(LIBC_NAMESPACE::rand(), vals[i]);
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#endif
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}
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TEST(LlvmLibcRandTest, SetSeed) {
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const unsigned int SEED = 12344321;
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LIBC_NAMESPACE::srand(SEED);
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const size_t NUM_RESULTS = 10;
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int results[NUM_RESULTS];
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for (size_t i = 0; i < NUM_RESULTS; ++i) {
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results[i] = LIBC_NAMESPACE::rand();
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ASSERT_GE(results[i], 0);
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ASSERT_LE(results[i], RAND_MAX);
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}
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// If the seed is set to the same value, it should give the same sequence.
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LIBC_NAMESPACE::srand(SEED);
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for (size_t i = 0; i < NUM_RESULTS; ++i) {
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int val = LIBC_NAMESPACE::rand();
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EXPECT_EQ(results[i], val);
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}
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}
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