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llvm-mirror/lib/MC/MCSectionWasm.cpp
Derek Schuff d4257740dd [WebAssembly] Support COMDAT sections in assembly syntax
This CL changes the asm syntax for section flags, making them more like ELF
(previously "passive" was the only option). Now we also allow "G" to designate
COMDAT group sections. In these sections we set the appropriate comdat flag on
function symbols, and also avoid auto-creating a new section for them.

This also adds asm-based tests for the changes D92691 to go along with
the direct-to-object tests.

Differential Revision: https://reviews.llvm.org/D92952
This is a reland of rG4564553b8d8a with a fix to the lit pipeline in
llvm/test/MC/WebAssembly/comdat.ll
2020-12-10 16:43:59 -08:00

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//===- lib/MC/MCSectionWasm.cpp - Wasm Code Section Representation --------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCSectionWasm.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCSymbolWasm.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
// Decides whether a '.section' directive
// should be printed before the section name.
bool MCSectionWasm::shouldOmitSectionDirective(StringRef Name,
const MCAsmInfo &MAI) const {
return MAI.shouldOmitSectionDirective(Name);
}
static void printName(raw_ostream &OS, StringRef Name) {
if (Name.find_first_not_of("0123456789_."
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ") == Name.npos) {
OS << Name;
return;
}
OS << '"';
for (const char *B = Name.begin(), *E = Name.end(); B < E; ++B) {
if (*B == '"') // Unquoted "
OS << "\\\"";
else if (*B != '\\') // Neither " or backslash
OS << *B;
else if (B + 1 == E) // Trailing backslash
OS << "\\\\";
else {
OS << B[0] << B[1]; // Quoted character
++B;
}
}
OS << '"';
}
void MCSectionWasm::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
raw_ostream &OS,
const MCExpr *Subsection) const {
if (shouldOmitSectionDirective(getName(), MAI)) {
OS << '\t' << getName();
if (Subsection) {
OS << '\t';
Subsection->print(OS, &MAI);
}
OS << '\n';
return;
}
OS << "\t.section\t";
printName(OS, getName());
OS << ",\"";
if (IsPassive)
OS << "p";
if (Group)
OS << "G";
OS << '"';
OS << ',';
// If comment string is '@', e.g. as on ARM - use '%' instead
if (MAI.getCommentString()[0] == '@')
OS << '%';
else
OS << '@';
// TODO: Print section type.
if (Group) {
OS << ",";
printName(OS, Group->getName());
OS << ",comdat";
}
if (isUnique())
OS << ",unique," << UniqueID;
OS << '\n';
if (Subsection) {
OS << "\t.subsection\t";
Subsection->print(OS, &MAI);
OS << '\n';
}
}
bool MCSectionWasm::UseCodeAlign() const { return false; }
bool MCSectionWasm::isVirtualSection() const { return false; }