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//===- InlineAsm.cpp - Implement the InlineAsm class ----------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the InlineAsm class.
//
//===----------------------------------------------------------------------===//
#include "llvm/IR/InlineAsm.h"
#include "ConstantsContext.h"
#include "LLVMContextImpl.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Value.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Errc.h"
#include <algorithm>
#include <cassert>
#include <cctype>
#include <cstdlib>
using namespace llvm;
InlineAsm::InlineAsm(FunctionType *FTy, const std::string &asmString,
const std::string &constraints, bool hasSideEffects,
bool isAlignStack, AsmDialect asmDialect, bool canThrow)
: Value(PointerType::getUnqual(FTy), Value::InlineAsmVal),
AsmString(asmString), Constraints(constraints), FTy(FTy),
HasSideEffects(hasSideEffects), IsAlignStack(isAlignStack),
Dialect(asmDialect), CanThrow(canThrow) {
#ifndef NDEBUG
// Do various checks on the constraint string and type.
cantFail(verify(getFunctionType(), constraints));
#endif
}
InlineAsm *InlineAsm::get(FunctionType *FTy, StringRef AsmString,
StringRef Constraints, bool hasSideEffects,
bool isAlignStack, AsmDialect asmDialect,
bool canThrow) {
InlineAsmKeyType Key(AsmString, Constraints, FTy, hasSideEffects,
isAlignStack, asmDialect, canThrow);
LLVMContextImpl *pImpl = FTy->getContext().pImpl;
return pImpl->InlineAsms.getOrCreate(PointerType::getUnqual(FTy), Key);
}
void InlineAsm::destroyConstant() {
getType()->getContext().pImpl->InlineAsms.remove(this);
delete this;
}
FunctionType *InlineAsm::getFunctionType() const {
return FTy;
}
void InlineAsm::collectAsmStrs(SmallVectorImpl<StringRef> &AsmStrs) const {
StringRef AsmStr(AsmString);
AsmStrs.clear();
// TODO: 1) Unify delimiter for inline asm, we also meet other delimiters
// for example "\0A", ";".
// 2) Enhance StringRef. Some of the special delimiter ("\0") can't be
// split in StringRef. Also empty StringRef can not call split (will stuck).
if (AsmStr.empty())
return;
AsmStr.split(AsmStrs, "\n\t", -1, false);
}
/// Parse - Analyze the specified string (e.g. "==&{eax}") and fill in the
/// fields in this structure. If the constraint string is not understood,
/// return true, otherwise return false.
bool InlineAsm::ConstraintInfo::Parse(StringRef Str,
InlineAsm::ConstraintInfoVector &ConstraintsSoFar) {
StringRef::iterator I = Str.begin(), E = Str.end();
unsigned multipleAlternativeCount = Str.count('|') + 1;
unsigned multipleAlternativeIndex = 0;
ConstraintCodeVector *pCodes = &Codes;
// Initialize
isMultipleAlternative = multipleAlternativeCount > 1;
if (isMultipleAlternative) {
multipleAlternatives.resize(multipleAlternativeCount);
pCodes = &multipleAlternatives[0].Codes;
}
Type = isInput;
isEarlyClobber = false;
MatchingInput = -1;
isCommutative = false;
isIndirect = false;
currentAlternativeIndex = 0;
// Parse prefixes.
if (*I == '~') {
Type = isClobber;
++I;
// '{' must immediately follow '~'.
if (I != E && *I != '{')
return true;
} else if (*I == '=') {
++I;
Type = isOutput;
} else if (*I == '!') {
++I;
Type = isLabel;
}
if (*I == '*') {
isIndirect = true;
++I;
}
if (I == E) return true; // Just a prefix, like "==" or "~".
// Parse the modifiers.
bool DoneWithModifiers = false;
while (!DoneWithModifiers) {
switch (*I) {
default:
DoneWithModifiers = true;
break;
case '&': // Early clobber.
if (Type != isOutput || // Cannot early clobber anything but output.
isEarlyClobber) // Reject &&&&&&
return true;
isEarlyClobber = true;
break;
case '%': // Commutative.
if (Type == isClobber || // Cannot commute clobbers.
isCommutative) // Reject %%%%%
return true;
isCommutative = true;
break;
case '#': // Comment.
case '*': // Register preferencing.
return true; // Not supported.
}
if (!DoneWithModifiers) {
++I;
if (I == E) return true; // Just prefixes and modifiers!
}
}
// Parse the various constraints.
while (I != E) {
if (*I == '{') { // Physical register reference.
// Find the end of the register name.
StringRef::iterator ConstraintEnd = std::find(I+1, E, '}');
if (ConstraintEnd == E) return true; // "{foo"
pCodes->push_back(std::string(StringRef(I, ConstraintEnd + 1 - I)));
I = ConstraintEnd+1;
} else if (isdigit(static_cast<unsigned char>(*I))) { // Matching Constraint
// Maximal munch numbers.
StringRef::iterator NumStart = I;
while (I != E && isdigit(static_cast<unsigned char>(*I)))
++I;
pCodes->push_back(std::string(StringRef(NumStart, I - NumStart)));
unsigned N = atoi(pCodes->back().c_str());
// Check that this is a valid matching constraint!
if (N >= ConstraintsSoFar.size() || ConstraintsSoFar[N].Type != isOutput||
Type != isInput)
return true; // Invalid constraint number.
// If Operand N already has a matching input, reject this. An output
// can't be constrained to the same value as multiple inputs.
if (isMultipleAlternative) {
if (multipleAlternativeIndex >=
ConstraintsSoFar[N].multipleAlternatives.size())
return true;
InlineAsm::SubConstraintInfo &scInfo =
ConstraintsSoFar[N].multipleAlternatives[multipleAlternativeIndex];
if (scInfo.MatchingInput != -1)
return true;
// Note that operand #n has a matching input.
scInfo.MatchingInput = ConstraintsSoFar.size();
assert(scInfo.MatchingInput >= 0);
} else {
if (ConstraintsSoFar[N].hasMatchingInput() &&
(size_t)ConstraintsSoFar[N].MatchingInput !=
ConstraintsSoFar.size())
return true;
// Note that operand #n has a matching input.
ConstraintsSoFar[N].MatchingInput = ConstraintsSoFar.size();
assert(ConstraintsSoFar[N].MatchingInput >= 0);
}
} else if (*I == '|') {
multipleAlternativeIndex++;
pCodes = &multipleAlternatives[multipleAlternativeIndex].Codes;
++I;
} else if (*I == '^') {
// Multi-letter constraint
// FIXME: For now assuming these are 2-character constraints.
pCodes->push_back(std::string(StringRef(I + 1, 2)));
I += 3;
} else if (*I == '@') {
// Multi-letter constraint
++I;
unsigned char C = static_cast<unsigned char>(*I);
assert(isdigit(C) && "Expected a digit!");
int N = C - '0';
assert(N > 0 && "Found a zero letter constraint!");
++I;
pCodes->push_back(std::string(StringRef(I, N)));
I += N;
} else {
// Single letter constraint.
pCodes->push_back(std::string(StringRef(I, 1)));
++I;
}
}
return false;
}
/// selectAlternative - Point this constraint to the alternative constraint
/// indicated by the index.
void InlineAsm::ConstraintInfo::selectAlternative(unsigned index) {
if (index < multipleAlternatives.size()) {
currentAlternativeIndex = index;
InlineAsm::SubConstraintInfo &scInfo =
multipleAlternatives[currentAlternativeIndex];
MatchingInput = scInfo.MatchingInput;
Codes = scInfo.Codes;
}
}
InlineAsm::ConstraintInfoVector
InlineAsm::ParseConstraints(StringRef Constraints) {
ConstraintInfoVector Result;
// Scan the constraints string.
for (StringRef::iterator I = Constraints.begin(),
E = Constraints.end(); I != E; ) {
ConstraintInfo Info;
// Find the end of this constraint.
StringRef::iterator ConstraintEnd = std::find(I, E, ',');
if (ConstraintEnd == I || // Empty constraint like ",,"
Info.Parse(StringRef(I, ConstraintEnd-I), Result)) {
Result.clear(); // Erroneous constraint?
break;
}
Result.push_back(Info);
// ConstraintEnd may be either the next comma or the end of the string. In
// the former case, we skip the comma.
I = ConstraintEnd;
if (I != E) {
++I;
if (I == E) {
Result.clear();
break;
} // don't allow "xyz,"
}
}
return Result;
}
static Error makeStringError(const char *Msg) {
return createStringError(errc::invalid_argument, Msg);
}
Error InlineAsm::verify(FunctionType *Ty, StringRef ConstStr) {
if (Ty->isVarArg())
return makeStringError("inline asm cannot be variadic");
ConstraintInfoVector Constraints = ParseConstraints(ConstStr);
// Error parsing constraints.
if (Constraints.empty() && !ConstStr.empty())
return makeStringError("failed to parse constraints");
unsigned NumOutputs = 0, NumInputs = 0, NumClobbers = 0;
unsigned NumIndirect = 0, NumLabels = 0;
for (const ConstraintInfo &Constraint : Constraints) {
switch (Constraint.Type) {
case InlineAsm::isOutput:
if ((NumInputs-NumIndirect) != 0 || NumClobbers != 0 || NumLabels != 0)
return makeStringError("output constraint occurs after input, "
"clobber or label constraint");
if (!Constraint.isIndirect) {
++NumOutputs;
break;
}
++NumIndirect;
[[fallthrough]]; // We fall through for Indirect Outputs.
case InlineAsm::isInput:
if (NumClobbers)
return makeStringError("input constraint occurs after clobber "
"constraint");
++NumInputs;
break;
case InlineAsm::isClobber:
++NumClobbers;
break;
case InlineAsm::isLabel:
if (NumClobbers)
return makeStringError("label constraint occurs after clobber "
"constraint");
++NumLabels;
break;
}
}
switch (NumOutputs) {
case 0:
if (!Ty->getReturnType()->isVoidTy())
return makeStringError("inline asm without outputs must return void");
break;
case 1:
if (Ty->getReturnType()->isStructTy())
return makeStringError("inline asm with one output cannot return struct");
break;
default:
StructType *STy = dyn_cast<StructType>(Ty->getReturnType());
if (!STy || STy->getNumElements() != NumOutputs)
return makeStringError("number of output constraints does not match "
"number of return struct elements");
break;
}
if (Ty->getNumParams() != NumInputs)
return makeStringError("number of input constraints does not match number "
"of parameters");
// We don't have access to labels here, NumLabels will be checked separately.
return Error::success();
}
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