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This essentially reverts some of the SimplifyLibcalls part changes of D45736 [SimplifyLibcalls] Replace locked IO with unlocked IO. C11 7.21.5.2 The fflush function > If stream is a null pointer, the fflush function performs this flushing action on all streams for which the behavior is defined above. i.e. fopen'ed FILE* is inherently captured. POSIX.1-2017 getc_unlocked, getchar_unlocked, putc_unlocked, putchar_unlocked - stdio with explicit client locking > These functions can safely be used in a multi-threaded program if and only if they are called while the invoking thread owns the ( FILE *) object, as is the case after a successful call to the flockfile() or ftrylockfile() functions. After a thread fopen'ed a FILE*, when it is calling foobar() which is now replaced by foobar_unlocked(), if another thread is concurrently calling fflush(0), the behavior is undefined. C11 7.22.4.4 The exit function > Next, all open streams with unwritten buffered data are flushed, all open streams are closed, and all files created by the tmpfile function are removed. The replacement is only feasible if the program is single threaded, or exit or fflush(0) is never called. See also http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20180528/556615.html for how the replacement makes libc interceptors difficult to implement. dalias: in a worst case, it's unbounded data corruption because of concurrent access to pointers without synchronization. f->wpos or rpos could get outside of the buffer, thread A could do f->wpos += j after knowing j is in bounds, while thread B also changes it concurrently. This can produce exploitable conditions depending on libc internals. Revert the SimplifyLibcalls part change because the cons obviously overweigh the pros. Even when the replacement is feasible, the benefit is indemonstrable, more so in an application instead of an artificial glibc benchmark. Theoretically the replacement could be beneficial when calling getc_unlocked/putc_unlocked in a loop, but then it is better using a blocked IO operation and the user is likely aware of that. The function attribute inference is still useful and thus kept. Reviewed By: xbolva00 Differential Revision: https://reviews.llvm.org/D75933
210 lines
9.7 KiB
C++
210 lines
9.7 KiB
C++
//===- BuildLibCalls.h - Utility builder for libcalls -----------*- C++ -*-===//
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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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//
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// This file exposes an interface to build some C language libcalls for
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// optimization passes that need to call the various functions.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_UTILS_BUILDLIBCALLS_H
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#define LLVM_TRANSFORMS_UTILS_BUILDLIBCALLS_H
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#include "llvm/Analysis/TargetLibraryInfo.h"
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namespace llvm {
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class Value;
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class DataLayout;
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class TargetLibraryInfo;
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class IRBuilderBase;
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/// Analyze the name and prototype of the given function and set any
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/// applicable attributes.
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/// If the library function is unavailable, this doesn't modify it.
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///
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/// Returns true if any attributes were set and false otherwise.
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bool inferLibFuncAttributes(Function &F, const TargetLibraryInfo &TLI);
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bool inferLibFuncAttributes(Module *M, StringRef Name, const TargetLibraryInfo &TLI);
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/// Check whether the overloaded floating point function
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/// corresponding to \a Ty is available.
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bool hasFloatFn(const TargetLibraryInfo *TLI, Type *Ty,
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LibFunc DoubleFn, LibFunc FloatFn, LibFunc LongDoubleFn);
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/// Get the name of the overloaded floating point function
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/// corresponding to \a Ty.
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StringRef getFloatFnName(const TargetLibraryInfo *TLI, Type *Ty,
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LibFunc DoubleFn, LibFunc FloatFn,
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LibFunc LongDoubleFn);
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/// Return V if it is an i8*, otherwise cast it to i8*.
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Value *castToCStr(Value *V, IRBuilderBase &B);
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/// Emit a call to the strlen function to the builder, for the specified
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/// pointer. Ptr is required to be some pointer type, and the return value has
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/// 'intptr_t' type.
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Value *emitStrLen(Value *Ptr, IRBuilderBase &B, const DataLayout &DL,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the strdup function to the builder, for the specified
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/// pointer. Ptr is required to be some pointer type, and the return value has
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/// 'i8*' type.
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Value *emitStrDup(Value *Ptr, IRBuilderBase &B, const TargetLibraryInfo *TLI);
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/// Emit a call to the strnlen function to the builder, for the specified
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/// pointer. Ptr is required to be some pointer type, MaxLen must be of size_t
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/// type, and the return value has 'intptr_t' type.
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Value *emitStrNLen(Value *Ptr, Value *MaxLen, IRBuilderBase &B,
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const DataLayout &DL, const TargetLibraryInfo *TLI);
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/// Emit a call to the strchr function to the builder, for the specified
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/// pointer and character. Ptr is required to be some pointer type, and the
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/// return value has 'i8*' type.
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Value *emitStrChr(Value *Ptr, char C, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the strncmp function to the builder.
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Value *emitStrNCmp(Value *Ptr1, Value *Ptr2, Value *Len, IRBuilderBase &B,
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const DataLayout &DL, const TargetLibraryInfo *TLI);
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/// Emit a call to the strcpy function to the builder, for the specified
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/// pointer arguments.
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Value *emitStrCpy(Value *Dst, Value *Src, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the stpcpy function to the builder, for the specified
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/// pointer arguments.
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Value *emitStpCpy(Value *Dst, Value *Src, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the strncpy function to the builder, for the specified
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/// pointer arguments and length.
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Value *emitStrNCpy(Value *Dst, Value *Src, Value *Len, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the stpncpy function to the builder, for the specified
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/// pointer arguments and length.
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Value *emitStpNCpy(Value *Dst, Value *Src, Value *Len, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the __memcpy_chk function to the builder. This expects that
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/// the Len and ObjSize have type 'intptr_t' and Dst/Src are pointers.
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Value *emitMemCpyChk(Value *Dst, Value *Src, Value *Len, Value *ObjSize,
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IRBuilderBase &B, const DataLayout &DL,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the memchr function. This assumes that Ptr is a pointer,
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/// Val is an i32 value, and Len is an 'intptr_t' value.
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Value *emitMemChr(Value *Ptr, Value *Val, Value *Len, IRBuilderBase &B,
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const DataLayout &DL, const TargetLibraryInfo *TLI);
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/// Emit a call to the memcmp function.
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Value *emitMemCmp(Value *Ptr1, Value *Ptr2, Value *Len, IRBuilderBase &B,
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const DataLayout &DL, const TargetLibraryInfo *TLI);
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/// Emit a call to the bcmp function.
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Value *emitBCmp(Value *Ptr1, Value *Ptr2, Value *Len, IRBuilderBase &B,
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const DataLayout &DL, const TargetLibraryInfo *TLI);
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/// Emit a call to the memccpy function.
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Value *emitMemCCpy(Value *Ptr1, Value *Ptr2, Value *Val, Value *Len,
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IRBuilderBase &B, const TargetLibraryInfo *TLI);
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/// Emit a call to the snprintf function.
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Value *emitSNPrintf(Value *Dest, Value *Size, Value *Fmt,
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ArrayRef<Value *> Args, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the sprintf function.
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Value *emitSPrintf(Value *Dest, Value *Fmt, ArrayRef<Value *> VariadicArgs,
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IRBuilderBase &B, const TargetLibraryInfo *TLI);
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/// Emit a call to the strcat function.
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Value *emitStrCat(Value *Dest, Value *Src, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the strlcpy function.
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Value *emitStrLCpy(Value *Dest, Value *Src, Value *Size, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the strlcat function.
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Value *emitStrLCat(Value *Dest, Value *Src, Value *Size, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the strncat function.
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Value *emitStrNCat(Value *Dest, Value *Src, Value *Size, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the vsnprintf function.
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Value *emitVSNPrintf(Value *Dest, Value *Size, Value *Fmt, Value *VAList,
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IRBuilderBase &B, const TargetLibraryInfo *TLI);
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/// Emit a call to the vsprintf function.
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Value *emitVSPrintf(Value *Dest, Value *Fmt, Value *VAList, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the unary function named 'Name' (e.g. 'floor'). This
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/// function is known to take a single of type matching 'Op' and returns one
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/// value with the same type. If 'Op' is a long double, 'l' is added as the
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/// suffix of name, if 'Op' is a float, we add a 'f' suffix.
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Value *emitUnaryFloatFnCall(Value *Op, StringRef Name, IRBuilderBase &B,
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const AttributeList &Attrs);
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/// Emit a call to the unary function DoubleFn, FloatFn or LongDoubleFn,
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/// depending of the type of Op.
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Value *emitUnaryFloatFnCall(Value *Op, const TargetLibraryInfo *TLI,
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LibFunc DoubleFn, LibFunc FloatFn,
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LibFunc LongDoubleFn, IRBuilderBase &B,
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const AttributeList &Attrs);
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/// Emit a call to the binary function named 'Name' (e.g. 'fmin'). This
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/// function is known to take type matching 'Op1' and 'Op2' and return one
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/// value with the same type. If 'Op1/Op2' are long double, 'l' is added as
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/// the suffix of name, if 'Op1/Op2' are float, we add a 'f' suffix.
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Value *emitBinaryFloatFnCall(Value *Op1, Value *Op2, StringRef Name,
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IRBuilderBase &B, const AttributeList &Attrs);
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/// Emit a call to the binary function DoubleFn, FloatFn or LongDoubleFn,
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/// depending of the type of Op1.
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Value *emitBinaryFloatFnCall(Value *Op1, Value *Op2,
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const TargetLibraryInfo *TLI, LibFunc DoubleFn,
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LibFunc FloatFn, LibFunc LongDoubleFn,
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IRBuilderBase &B, const AttributeList &Attrs);
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/// Emit a call to the putchar function. This assumes that Char is an integer.
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Value *emitPutChar(Value *Char, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the puts function. This assumes that Str is some pointer.
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Value *emitPutS(Value *Str, IRBuilderBase &B, const TargetLibraryInfo *TLI);
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/// Emit a call to the fputc function. This assumes that Char is an i32, and
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/// File is a pointer to FILE.
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Value *emitFPutC(Value *Char, Value *File, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the fputs function. Str is required to be a pointer and
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/// File is a pointer to FILE.
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Value *emitFPutS(Value *Str, Value *File, IRBuilderBase &B,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the fwrite function. This assumes that Ptr is a pointer,
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/// Size is an 'intptr_t', and File is a pointer to FILE.
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Value *emitFWrite(Value *Ptr, Value *Size, Value *File, IRBuilderBase &B,
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const DataLayout &DL, const TargetLibraryInfo *TLI);
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/// Emit a call to the malloc function.
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Value *emitMalloc(Value *Num, IRBuilderBase &B, const DataLayout &DL,
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const TargetLibraryInfo *TLI);
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/// Emit a call to the calloc function.
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Value *emitCalloc(Value *Num, Value *Size, const AttributeList &Attrs,
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IRBuilderBase &B, const TargetLibraryInfo &TLI);
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}
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#endif
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