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10c3102071
On some targets, passing zero to the clz() or ctz() builtins has undefined behavior. I ran into this issue while debugging UB in __hash_table from libcxx: the bug I was seeing manifested itself differently under -O0 vs -Os, due to a UB call to clz() (see: libcxx/r304617). This patch introduces a check which can detect UB calls to builtins. llvm.org/PR26979 Differential Revision: https://reviews.llvm.org/D34590 llvm-svn: 309459
45 lines
1.3 KiB
C
45 lines
1.3 KiB
C
// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -w -emit-llvm -o - %s -fsanitize=builtin | FileCheck %s
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// RUN: %clang_cc1 -triple arm64-none-linux-gnu -w -emit-llvm -o - %s -fsanitize=builtin | FileCheck %s --check-prefix=NOT-UB
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// NOT-UB-NOT: __ubsan_handle_invalid_builtin
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// CHECK: define void @check_ctz
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void check_ctz(int n) {
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// CHECK: [[NOT_ZERO:%.*]] = icmp ne i32 [[N:%.*]], 0, !nosanitize
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// CHECK-NEXT: br i1 [[NOT_ZERO]]
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//
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// Handler block:
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// CHECK: call void @__ubsan_handle_invalid_builtin
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// CHECK-NEXT: unreachable
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//
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// Continuation block:
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// CHECK: call i32 @llvm.cttz.i32(i32 [[N]], i1 true)
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__builtin_ctz(n);
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// CHECK: call void @__ubsan_handle_invalid_builtin
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__builtin_ctzl(n);
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// CHECK: call void @__ubsan_handle_invalid_builtin
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__builtin_ctzll(n);
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}
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// CHECK: define void @check_clz
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void check_clz(int n) {
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// CHECK: [[NOT_ZERO:%.*]] = icmp ne i32 [[N:%.*]], 0, !nosanitize
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// CHECK-NEXT: br i1 [[NOT_ZERO]]
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//
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// Handler block:
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// CHECK: call void @__ubsan_handle_invalid_builtin
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// CHECK-NEXT: unreachable
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//
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// Continuation block:
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// CHECK: call i32 @llvm.ctlz.i32(i32 [[N]], i1 true)
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__builtin_clz(n);
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// CHECK: call void @__ubsan_handle_invalid_builtin
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__builtin_clzl(n);
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// CHECK: call void @__ubsan_handle_invalid_builtin
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__builtin_clzll(n);
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}
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