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1711996805
In the LLVM middle-end we want to fold `gep inbounds null, idx -> null`: https://alive2.llvm.org/ce/z/5ZkPx- This pattern is common in real-world programs (https://github.com/dtcxzyw/llvm-opt-benchmark/pull/55#issuecomment-1870963906). Generally, it exists in some (actually) unreachable blocks, which is introduced by JumpThreading. However, some old-style offsetof macros are still widely used in real-world C/C++ code (e.g., hwloc/slurm/luajit). To avoid breaking existing code and inconvenience to downstream users, this patch removes the inbounds flag from the struct gep if the base pointer is null.
96 lines
3.1 KiB
C++
96 lines
3.1 KiB
C++
// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py
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// RUN: %clang_cc1 -x c++ -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s
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// RUN: %clang_cc1 -x c++ -fsanitize=pointer-overflow -fno-sanitize-recover=pointer-overflow -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s
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#include <stdint.h>
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struct S {
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int x, y;
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};
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// CHECK-LABEL: @_Z23get_offset_of_y_naivelyv(
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// CHECK-NEXT: entry:
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// CHECK-NEXT: ret i64 ptrtoint (ptr getelementptr ([[STRUCT_S:%.*]], ptr null, i32 0, i32 1) to i64)
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//
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uintptr_t get_offset_of_y_naively() {
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return ((uintptr_t)(&(((S *)nullptr)->y)));
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}
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struct Empty {};
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struct T {
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int a;
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S s;
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[[no_unique_address]] Empty e1;
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int b;
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[[no_unique_address]] Empty e2;
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};
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// CHECK-LABEL: @_Z30get_offset_of_y_naively_nestedv(
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// CHECK-NEXT: entry:
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// CHECK-NEXT: ret i64 ptrtoint (ptr getelementptr ([[STRUCT_S:%.*]], ptr getelementptr ([[STRUCT_T:%.*]], ptr null, i32 0, i32 1), i32 0, i32 1) to i64)
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//
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uintptr_t get_offset_of_y_naively_nested() {
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return ((uintptr_t)(&(((T *)nullptr)->s.y)));
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}
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// CHECK-LABEL: @_Z42get_offset_of_y_naively_nested_with_parensv(
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// CHECK-NEXT: entry:
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// CHECK-NEXT: ret i64 ptrtoint (ptr getelementptr ([[STRUCT_S:%.*]], ptr getelementptr ([[STRUCT_T:%.*]], ptr null, i32 0, i32 1), i32 0, i32 1) to i64)
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//
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uintptr_t get_offset_of_y_naively_nested_with_parens() {
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return ((uintptr_t)(&((((T *)nullptr)->s).y)));
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}
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// CHECK-LABEL: @_Z26get_offset_of_zero_storagev(
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// CHECK-NEXT: entry:
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// CHECK-NEXT: ret i64 ptrtoint (ptr getelementptr (i8, ptr null, i64 16) to i64)
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//
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uintptr_t get_offset_of_zero_storage() {
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return ((uintptr_t)(&(((T *)nullptr)->e2)));
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}
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namespace std { typedef decltype(__nullptr) nullptr_t; }
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// CHECK-LABEL: @_Z29get_offset_of_y_integral_zerov(
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// CHECK-NEXT: entry:
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// CHECK-NEXT: ret i64 ptrtoint (ptr getelementptr ([[STRUCT_S:%.*]], ptr null, i32 0, i32 1) to i64)
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//
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uintptr_t get_offset_of_y_integral_zero() {
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return ((uintptr_t)(&(((S *)0)->y)));
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}
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// CHECK-LABEL: @_Z37get_offset_of_y_integral_zero_voidptrv(
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// CHECK-NEXT: entry:
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// CHECK-NEXT: ret i64 ptrtoint (ptr getelementptr ([[STRUCT_S:%.*]], ptr null, i32 0, i32 1) to i64)
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//
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uintptr_t get_offset_of_y_integral_zero_voidptr() {
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return ((uintptr_t)(&(((S *)(void*)0)->y)));
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}
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// CHECK-LABEL: @_Z25get_offset_of_y_nullptr_tv(
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// CHECK-NEXT: entry:
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// CHECK-NEXT: ret i64 ptrtoint (ptr getelementptr ([[STRUCT_S:%.*]], ptr null, i32 0, i32 1) to i64)
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//
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uintptr_t get_offset_of_y_nullptr_t() {
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return ((uintptr_t)(&(((S *)std::nullptr_t{})->y)));
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}
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// CHECK-LABEL: @_Z32get_offset_of_y_nullptr_constantv(
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// CHECK-NEXT: entry:
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// CHECK-NEXT: [[NULL:%.*]] = alloca ptr, align 8
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// CHECK-NEXT: store ptr null, ptr [[NULL]], align 8
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// CHECK-NEXT: ret i64 ptrtoint (ptr getelementptr inbounds nuw ([[STRUCT_S:%.*]], ptr null, i32 0, i32 1) to i64)
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//
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uintptr_t get_offset_of_y_nullptr_constant() {
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constexpr void *null = nullptr;
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return ((uintptr_t)(&(((S *)null)->y)));
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}
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// CHECK-LABEL: @_Z27get_offset_of_y_via_builtinv(
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// CHECK-NEXT: entry:
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// CHECK-NEXT: ret i64 4
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//
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uintptr_t get_offset_of_y_via_builtin() {
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return __builtin_offsetof(S, y);
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}
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