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MC: Simplify main section layout process by moving alignment into LayoutSection.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99529 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Daniel Dunbar 2010-03-25 18:16:42 +00:00
parent be644a38c0
commit f476b00f51
2 changed files with 36 additions and 32 deletions
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7
include/llvm/MC/MCAssembler.h
View File

@ -654,8 +654,11 @@ private:
/// LayoutSection - Assign the section the given \arg StartAddress, and then
/// assign offsets and sizes to the fragments in the section \arg SD, and
/// update the section size.
void LayoutSection(MCSectionData &SD, MCAsmLayout &Layout,
uint64_t StartAddress);
///
/// \return The address at the end of the section, for use in laying out the
/// succeeding section.
uint64_t LayoutSection(MCSectionData &SD, MCAsmLayout &Layout,
uint64_t StartAddress);
/// LayoutOnce - Perform one layout iteration and return true if any offsets
/// were adjusted.

61
lib/MC/MCAssembler.cpp
View File

@ -364,9 +364,29 @@ bool MCAssembler::EvaluateFixup(const MCAsmLayout &Layout,
return IsResolved;
}
void MCAssembler::LayoutSection(MCSectionData &SD,
MCAsmLayout &Layout,
uint64_t StartAddress) {
uint64_t MCAssembler::LayoutSection(MCSectionData &SD,
MCAsmLayout &Layout,
uint64_t StartAddress) {
bool IsVirtual = getBackend().isVirtualSection(SD.getSection());
// Align this section if necessary by adding padding bytes to the previous
// section. It is safe to adjust this out-of-band, because no symbol or
// fragment is allowed to point past the end of the section at any time.
if (uint64_t Pad = OffsetToAlignment(StartAddress, SD.getAlignment())) {
// Unless this section is virtual (where we are allowed to adjust the offset
// freely), the padding goes in the previous section.
if (!IsVirtual) {
// Find the previous non-virtual section.
iterator it = &SD;
assert(it != begin() && "Invalid initial section address!");
for (--it; getBackend().isVirtualSection(it->getSection()); --it) ;
Layout.setSectionFileSize(&*it, Layout.getSectionFileSize(&*it) + Pad);
}
StartAddress += Pad;
}
// Set the aligned section address.
Layout.setSectionAddress(&SD, StartAddress);
uint64_t Address = StartAddress;
@ -440,10 +460,12 @@ void MCAssembler::LayoutSection(MCSectionData &SD,
// Set the section sizes.
Layout.setSectionSize(&SD, Address - StartAddress);
if (getBackend().isVirtualSection(SD.getSection()))
if (IsVirtual)
Layout.setSectionFileSize(&SD, 0);
else
Layout.setSectionFileSize(&SD, Address - StartAddress);
return Address;
}
/// WriteFragmentData - Write the \arg F data to the output file.
@ -675,43 +697,22 @@ bool MCAssembler::LayoutOnce(MCAsmLayout &Layout) {
// Layout the concrete sections and fragments.
uint64_t Address = 0;
MCSectionData *Prev = 0;
for (iterator it = begin(), ie = end(); it != ie; ++it) {
MCSectionData &SD = *it;
// Skip virtual sections.
if (getBackend().isVirtualSection(SD.getSection()))
if (getBackend().isVirtualSection(it->getSection()))
continue;
// Align this section if necessary by adding padding bytes to the previous
// section.
if (uint64_t Pad = OffsetToAlignment(Address, it->getAlignment())) {
assert(Prev && "Missing prev section!");
Layout.setSectionFileSize(Prev, Layout.getSectionFileSize(Prev) + Pad);
Address += Pad;
}
// Layout the section fragments and its size.
LayoutSection(SD, Layout, Address);
Address += Layout.getSectionFileSize(&SD);
Prev = &SD;
Address = LayoutSection(*it, Layout, Address);
}
// Layout the virtual sections.
for (iterator it = begin(), ie = end(); it != ie; ++it) {
MCSectionData &SD = *it;
if (!getBackend().isVirtualSection(SD.getSection()))
if (!getBackend().isVirtualSection(it->getSection()))
continue;
// Align this section if necessary by adding padding bytes to the previous
// section.
if (uint64_t Pad = OffsetToAlignment(Address, it->getAlignment()))
Address += Pad;
LayoutSection(SD, Layout, Address);
Address += Layout.getSectionSize(&SD);
// Layout the section fragments and its size.
Address = LayoutSection(*it, Layout, Address);
}
// Scan for fragments that need relaxation.