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[Sema] Demote call-site-based 'alignment is a power of two' check for AllocAlignAttr into a warning Summary: As @rsmith notes in https://reviews.llvm.org/D73020#inline-672219 while that is certainly UB land, it may not be actually reachable at runtime, e.g.: ``` template<int N> void *make() { if ((N & (N-1)) == 0) return operator new(N, std::align_val_t(N)); else return operator new(N); } void *p = make<7>(); ``` and we shouldn't really error-out there. That being said, i'm not really following the logic here. Which ones of these cases should remain being an error? Reviewers: rsmith, erichkeane Reviewed By: erichkeane Subscribers: cfe-commits, rsmith Tags: #clang Differential Revision: https://reviews.llvm.org/D73996
2020-02-20 21:39:26 +08:00
// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm %s -o - | FileCheck %s
void *__attribute__((alloc_align(1))) alloc(int align);
// CHECK-LABEL: @t0(
// CHECK-NEXT: entry:
// CHECK-NEXT: [[ALIGN_ADDR:%.*]] = alloca i32, align 4
// CHECK-NEXT: store i32 [[ALIGN:%.*]], i32* [[ALIGN_ADDR]], align 4
// CHECK-NEXT: [[TMP0:%.*]] = load i32, i32* [[ALIGN_ADDR]], align 4
// CHECK-NEXT: [[CALL:%.*]] = call i8* @alloc(i32 [[TMP0]])
// CHECK-NEXT: [[ALIGNMENTCAST:%.*]] = zext i32 [[TMP0]] to i64
// CHECK-NEXT: [[MASK:%.*]] = sub i64 [[ALIGNMENTCAST]], 1
// CHECK-NEXT: [[PTRINT:%.*]] = ptrtoint i8* [[CALL]] to i64
// CHECK-NEXT: [[MASKEDPTR:%.*]] = and i64 [[PTRINT]], [[MASK]]
// CHECK-NEXT: [[MASKCOND:%.*]] = icmp eq i64 [[MASKEDPTR]], 0
// CHECK-NEXT: call void @llvm.assume(i1 [[MASKCOND]])
// CHECK-NEXT: ret void
//
void t0(int align) {
alloc(align);
}
// CHECK-LABEL: @t1(
// CHECK-NEXT: entry:
// CHECK-NEXT: [[ALIGN_ADDR:%.*]] = alloca i32, align 4
// CHECK-NEXT: store i32 [[ALIGN:%.*]], i32* [[ALIGN_ADDR]], align 4
// CHECK-NEXT: [[CALL:%.*]] = call i8* @alloc(i32 7)
// CHECK-NEXT: [[PTRINT:%.*]] = ptrtoint i8* [[CALL]] to i64
// CHECK-NEXT: [[MASKEDPTR:%.*]] = and i64 [[PTRINT]], 6
// CHECK-NEXT: [[MASKCOND:%.*]] = icmp eq i64 [[MASKEDPTR]], 0
// CHECK-NEXT: call void @llvm.assume(i1 [[MASKCOND]])
// CHECK-NEXT: ret void
//
void t1(int align) {
alloc(7);
}
// CHECK-LABEL: @t2(
// CHECK-NEXT: entry:
// CHECK-NEXT: [[ALIGN_ADDR:%.*]] = alloca i32, align 4
// CHECK-NEXT: store i32 [[ALIGN:%.*]], i32* [[ALIGN_ADDR]], align 4
// CHECK-NEXT: [[CALL:%.*]] = call align 8 i8* @alloc(i32 8)
// CHECK-NEXT: ret void
//
void t2(int align) {
alloc(8);
}