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d919115983
Currently, ubsan emits overflow checks for arithmetic that is known to be safe at compile-time, e.g: 1 + 1 => CheckedAdd(1, 1) This leads to breakage when using the __builtin_prefetch intrinsic. LLVM expects the arguments to @llvm.prefetch to be constant integers, and when ubsan inserts unnecessary checks on the operands to the intrinsic, this contract is broken, leading to verifier failures (see PR32874). Instead of special-casing __builtin_prefetch for ubsan, this patch fixes the underlying problem, i.e that clang currently emits unnecessary overflow checks. Testing: I ran the check-clang and check-ubsan targets with a stage2, ubsan-enabled build of clang. I added a regression test for PR32874, and some extra checking to make sure we don't regress runtime checking for unsafe arithmetic. The existing ubsan-promoted-arithmetic.cpp test also provides coverage for this change. llvm-svn: 301988
62 lines
2.0 KiB
C
62 lines
2.0 KiB
C
// RUN: %clang_cc1 -x c -S -emit-llvm -o - -triple x86_64-apple-darwin10 %s \
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// RUN: -w -fsanitize=signed-integer-overflow,unsigned-integer-overflow,integer-divide-by-zero,float-divide-by-zero \
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// RUN: | FileCheck %s
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// CHECK-LABEL: define void @foo
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// CHECK-NOT: !nosanitize
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void foo(const int *p) {
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// __builtin_prefetch expects its optional arguments to be constant integers.
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// Check that ubsan does not instrument any safe arithmetic performed in
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// operands to __builtin_prefetch. (A clang frontend check should reject
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// unsafe arithmetic in these operands.)
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__builtin_prefetch(p, 0 + 1, 0 + 3);
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__builtin_prefetch(p, 1 - 0, 3 - 0);
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__builtin_prefetch(p, 1 * 1, 1 * 3);
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__builtin_prefetch(p, 1 / 1, 3 / 1);
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__builtin_prefetch(p, 3 % 2, 3 % 1);
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__builtin_prefetch(p, 0U + 1U, 0U + 3U);
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__builtin_prefetch(p, 1U - 0U, 3U - 0U);
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__builtin_prefetch(p, 1U * 1U, 1U * 3U);
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__builtin_prefetch(p, 1U / 1U, 3U / 1U);
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__builtin_prefetch(p, 3U % 2U, 3U % 1U);
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}
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// CHECK-LABEL: define void @ub_constant_arithmetic
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void ub_constant_arithmetic() {
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// Check that we still instrument unsafe arithmetic, even if it is known to
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// be unsafe at compile time.
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int INT_MIN = 0xffffffff;
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int INT_MAX = 0x7fffffff;
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// CHECK: call void @__ubsan_handle_add_overflow
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// CHECK: call void @__ubsan_handle_add_overflow
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INT_MAX + 1;
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INT_MAX + -1;
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// CHECK: call void @__ubsan_handle_negate_overflow
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// CHECK: call void @__ubsan_handle_sub_overflow
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-INT_MIN;
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-INT_MAX - 2;
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// CHECK: call void @__ubsan_handle_mul_overflow
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// CHECK: call void @__ubsan_handle_mul_overflow
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INT_MAX * INT_MAX;
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INT_MIN * INT_MIN;
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// CHECK: call void @__ubsan_handle_divrem_overflow
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// CHECK: call void @__ubsan_handle_divrem_overflow
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1 / 0;
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INT_MIN / -1;
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// CHECK: call void @__ubsan_handle_divrem_overflow
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// CHECK: call void @__ubsan_handle_divrem_overflow
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1 % 0;
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INT_MIN % -1;
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// CHECK: call void @__ubsan_handle_divrem_overflow
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1.0 / 0.0;
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}
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