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[InlineAsm] Avoid creating extra string instances in ConstraintInfo::Parse() 

Don't create unnecessary std::string objects when pushing back to |pCodes|.
NFC.

llvm-svn: 270436
This commit is contained in:
Alexander Potapenko 2016-05-23 13:58:04 +00:00
parent c345705bee
commit 7d68c2604a
1 changed files with 4 additions and 4 deletions
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8
llvm/lib/IR/InlineAsm.cpp
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@ -142,14 +142,14 @@ bool InlineAsm::ConstraintInfo::Parse(StringRef Str,
// Find the end of the register name. // Find the end of the register name.
StringRef::iterator ConstraintEnd = std::find(I+1, E, '}'); StringRef::iterator ConstraintEnd = std::find(I+1, E, '}');
if (ConstraintEnd == E) return true; // "{foo" if (ConstraintEnd == E) return true; // "{foo"
pCodes->push_back(std::string(I, ConstraintEnd+1)); pCodes->push_back(StringRef(I, ConstraintEnd+1 - I));
I = ConstraintEnd+1; I = ConstraintEnd+1;
} else if (isdigit(static_cast<unsigned char>(*I))) { // Matching Constraint } else if (isdigit(static_cast<unsigned char>(*I))) { // Matching Constraint
// Maximal munch numbers. // Maximal munch numbers.
StringRef::iterator NumStart = I; StringRef::iterator NumStart = I;
while (I != E && isdigit(static_cast<unsigned char>(*I))) while (I != E && isdigit(static_cast<unsigned char>(*I)))
++I; ++I;
pCodes->push_back(std::string(NumStart, I)); pCodes->push_back(StringRef(NumStart, I - NumStart));
unsigned N = atoi(pCodes->back().c_str()); unsigned N = atoi(pCodes->back().c_str());
// Check that this is a valid matching constraint! // Check that this is a valid matching constraint!
if (N >= ConstraintsSoFar.size() || ConstraintsSoFar[N].Type != isOutput|| if (N >= ConstraintsSoFar.size() || ConstraintsSoFar[N].Type != isOutput||
@ -183,11 +183,11 @@ bool InlineAsm::ConstraintInfo::Parse(StringRef Str,
} else if (*I == '^') { } else if (*I == '^') {
// Multi-letter constraint // Multi-letter constraint
// FIXME: For now assuming these are 2-character constraints. // FIXME: For now assuming these are 2-character constraints.
pCodes->push_back(std::string(I+1, I+3)); pCodes->push_back(StringRef(I+1, 2));
I += 3; I += 3;
} else { } else {
// Single letter constraint. // Single letter constraint.
pCodes->push_back(std::string(I, I+1)); pCodes->push_back(StringRef(I, 1));
++I; ++I;
} }
} }