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[MCParser] Simplify macro-like body expansion
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Make it easy to support argument expansion in the altmacro mode.
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@MaskRay @kbluck
MaskRay authored and kbluck committed Jul 6, 2024
1 parent 496d2e1 commit f30de65
Showing 1 changed file with 73 additions and 106 deletions.
179 changes: 73 additions & 106 deletions llvm/lib/MC/MCParser/AsmParser.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2505,129 +2505,96 @@ bool AsmParser::expandMacro(raw_svector_ostream &OS, MCAsmMacro &Macro,
// A macro without parameters is handled differently on Darwin:
// gas accepts no arguments and does no substitutions
StringRef Body = Macro.Body;
while (!Body.empty()) {
// Scan for the next substitution.
std::size_t End = Body.size(), Pos = 0;
for (; Pos != End; ++Pos) {
// Check for a substitution or escape.
if (IsDarwin && !NParameters) {
// This macro has no parameters, look for $0, $1, etc.
if (Body[Pos] != '$' || Pos + 1 == End)
continue;
size_t I = 0, End = Body.size();
while (I != End) {
if (Body[I] == '\\' && I + 1 != End) {
// Check for \@ and \+ pseudo variables.
if (EnableAtPseudoVariable && Body[I + 1] == '@') {
OS << NumOfMacroInstantiations;
I += 2;
continue;
}
if (Body[I + 1] == '+') {
OS << Macro.Count;
I += 2;
continue;
}
if (Body[I + 1] == '(' && Body[I + 2] == ')') {
I += 3;
continue;
}

char Next = Body[Pos + 1];
if (Next == '$' || Next == 'n' ||
isdigit(static_cast<unsigned char>(Next)))
size_t Pos = ++I;
while (I != End && isIdentifierChar(Body[I]))
++I;
StringRef Argument(Body.data() + Pos, I - Pos);
unsigned Index = 0;
for (; Index < NParameters; ++Index)
if (Parameters[Index].Name == Argument)
break;
if (Index == NParameters) {
OS << '\\' << Argument;
} else {
// This macro has parameters, look for \foo, \bar, etc.
if (Body[Pos] == '\\' && Pos + 1 != End)
break;
bool VarargParameter = HasVararg && Index == (NParameters - 1);
for (const AsmToken &Token : A[Index]) {
// For altmacro mode, you can write '%expr'.
// The prefix '%' evaluates the expression 'expr'
// and uses the result as a string (e.g. replace %(1+2) with the
// string "3").
// Here, we identify the integer token which is the result of the
// absolute expression evaluation and replace it with its string
// representation.
if (AltMacroMode && Token.getString().front() == '%' &&
Token.is(AsmToken::Integer))
// Emit an integer value to the buffer.
OS << Token.getIntVal();
// Only Token that was validated as a string and begins with '<'
// is considered altMacroString!!!
else if (AltMacroMode && Token.getString().front() == '<' &&
Token.is(AsmToken::String)) {
OS << angleBracketString(Token.getStringContents());
}
// We expect no quotes around the string's contents when
// parsing for varargs.
else if (Token.isNot(AsmToken::String) || VarargParameter)
OS << Token.getString();
else
OS << Token.getStringContents();
}
}
continue;
}

// Add the prefix.
OS << Body.slice(0, Pos);

// Check if we reached the end.
if (Pos == End)
break;

if (IsDarwin && !NParameters) {
switch (Body[Pos + 1]) {
if (Body[I] == '$' && I + 1 != End && IsDarwin && !NParameters) {
// This macro has no parameters, look for $0, $1, etc.
switch (Body[I + 1]) {
// $$ => $
case '$':
OS << '$';
break;

I += 2;
continue;
// $n => number of arguments
case 'n':
OS << A.size();
break;

// $[0-9] => argument
I += 2;
continue;
default: {
// Missing arguments are ignored.
unsigned Index = Body[Pos + 1] - '0';
if (Index >= A.size())
if (!isDigit(Body[I + 1]))
break;

// Otherwise substitute with the token values, with spaces eliminated.
for (const AsmToken &Token : A[Index])
OS << Token.getString();
break;
}
}
Pos += 2;
} else {
// Check for \@ and \+ pseudo variables.
unsigned I = Pos + 1;
if (I + 1 != End) {
if (EnableAtPseudoVariable && Body[I] == '@') {
++I;
} else if (Body[I] == '+') {
++I;
} else {
while (isIdentifierChar(Body[I]) && I + 1 != End)
++I;
}
}

const char *Begin = Body.data() + Pos + 1;
StringRef Argument(Begin, I - (Pos + 1));
unsigned Index = 0;

if (Argument == "@") {
OS << NumOfMacroInstantiations;
Pos += 2;
} else if (Argument == "+") {
OS << Macro.Count;
Pos += 2;
} else {
for (; Index < NParameters; ++Index)
if (Parameters[Index].Name == Argument)
break;

if (Index == NParameters) {
if (Body[Pos + 1] == '(' && Body[Pos + 2] == ')')
Pos += 3;
else {
OS << '\\' << Argument;
Pos = I;
}
} else {
bool VarargParameter = HasVararg && Index == (NParameters - 1);
// $[0-9] => argument
// Missing arguments are ignored.
unsigned Index = Body[I + 1] - '0';
if (Index < A.size())
for (const AsmToken &Token : A[Index])
// For altmacro mode, you can write '%expr'.
// The prefix '%' evaluates the expression 'expr'
// and uses the result as a string (e.g. replace %(1+2) with the
// string "3").
// Here, we identify the integer token which is the result of the
// absolute expression evaluation and replace it with its string
// representation.
if (AltMacroMode && Token.getString().front() == '%' &&
Token.is(AsmToken::Integer))
// Emit an integer value to the buffer.
OS << Token.getIntVal();
// Only Token that was validated as a string and begins with '<'
// is considered altMacroString!!!
else if (AltMacroMode && Token.getString().front() == '<' &&
Token.is(AsmToken::String)) {
OS << angleBracketString(Token.getStringContents());
}
// We expect no quotes around the string's contents when
// parsing for varargs.
else if (Token.isNot(AsmToken::String) || VarargParameter)
OS << Token.getString();
else
OS << Token.getStringContents();

Pos += 1 + Argument.size();
}
OS << Token.getString();
I += 2;
continue;
}
}
}
// Update the scan point.
Body = Body.substr(Pos);

OS << Body[I];
++I;
}

++Macro.Count;
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