Optimize the memory usage of MC bundling, by creating a new type of fragment
into which we can emit single instructions without fixups (which is most
instructions). This is an optimization required because MCDataFragment
is prety large (240 bytes on x64), with no change in functionality.
For large programs, this reduces memory usage overhead required for bundling
by 40%.
To make the code as palatable as possible, the MCEncodedFragment interface was
further fragmented (no pun intended) and MCEncodedFragmentWithFixups is used
as the interface to work against when the user expects fixups. MCDataFragment
and MCRelaxableFragment implement this interface, while the new
MCCompactEncodedInstFragment implements MCEncodeFragment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172572 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCAssembler.cpp b/lib/MC/MCAssembler.cpp
index 5fdc57a..c51ddc8 100644
--- a/lib/MC/MCAssembler.cpp
+++ b/lib/MC/MCAssembler.cpp
@@ -38,6 +38,8 @@
"Number of emitted assembler fragments - relaxable");
STATISTIC(EmittedDataFragments,
"Number of emitted assembler fragments - data");
+STATISTIC(EmittedCompactEncodedInstFragments,
+ "Number of emitted assembler fragments - compact encoded inst");
STATISTIC(EmittedAlignFragments,
"Number of emitted assembler fragments - align");
STATISTIC(EmittedFillFragments,
@@ -222,6 +224,11 @@
/* *** */
+MCEncodedFragmentWithFixups::~MCEncodedFragmentWithFixups() {
+}
+
+/* *** */
+
MCSectionData::MCSectionData() : Section(0) {}
MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
@@ -388,6 +395,7 @@
switch (F.getKind()) {
case MCFragment::FT_Data:
case MCFragment::FT_Relaxable:
+ case MCFragment::FT_CompactEncodedInst:
return cast<MCEncodedFragment>(F).getContents().size();
case MCFragment::FT_Fill:
return cast<MCFillFragment>(F).getSize();
@@ -570,6 +578,11 @@
writeFragmentContents(F, OW);
break;
+ case MCFragment::FT_CompactEncodedInst:
+ ++stats::EmittedCompactEncodedInstFragments;
+ writeFragmentContents(F, OW);
+ break;
+
case MCFragment::FT_Fill: {
++stats::EmittedFillFragments;
MCFillFragment &FF = cast<MCFillFragment>(F);
@@ -742,9 +755,10 @@
for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
for (MCSectionData::iterator it2 = it->begin(),
ie2 = it->end(); it2 != ie2; ++it2) {
- MCEncodedFragment *F = dyn_cast<MCEncodedFragment>(it2);
+ MCEncodedFragmentWithFixups *F =
+ dyn_cast<MCEncodedFragmentWithFixups>(it2);
if (F) {
- for (MCEncodedFragment::fixup_iterator it3 = F->fixup_begin(),
+ for (MCEncodedFragmentWithFixups::fixup_iterator it3 = F->fixup_begin(),
ie3 = F->fixup_end(); it3 != ie3; ++it3) {
MCFixup &Fixup = *it3;
uint64_t FixedValue = handleFixup(Layout, *F, Fixup);
@@ -954,6 +968,8 @@
switch (getKind()) {
case MCFragment::FT_Align: OS << "MCAlignFragment"; break;
case MCFragment::FT_Data: OS << "MCDataFragment"; break;
+ case MCFragment::FT_CompactEncodedInst:
+ OS << "MCCompactEncodedInstFragment"; break;
case MCFragment::FT_Fill: OS << "MCFillFragment"; break;
case MCFragment::FT_Relaxable: OS << "MCRelaxableFragment"; break;
case MCFragment::FT_Org: OS << "MCOrgFragment"; break;
@@ -1001,6 +1017,19 @@
}
break;
}
+ case MCFragment::FT_CompactEncodedInst: {
+ const MCCompactEncodedInstFragment *CEIF =
+ cast<MCCompactEncodedInstFragment>(this);
+ OS << "\n ";
+ OS << " Contents:[";
+ const SmallVectorImpl<char> &Contents = CEIF->getContents();
+ for (unsigned i = 0, e = Contents.size(); i != e; ++i) {
+ if (i) OS << ",";
+ OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
+ }
+ OS << "] (" << Contents.size() << " bytes)";
+ break;
+ }
case MCFragment::FT_Fill: {
const MCFillFragment *FF = cast<MCFillFragment>(this);
OS << " Value:" << FF->getValue() << " ValueSize:" << FF->getValueSize()
@@ -1094,7 +1123,9 @@
// anchors for MC*Fragment vtables
void MCEncodedFragment::anchor() { }
+void MCEncodedFragmentWithFixups::anchor() { }
void MCDataFragment::anchor() { }
+void MCCompactEncodedInstFragment::anchor() { }
void MCRelaxableFragment::anchor() { }
void MCAlignFragment::anchor() { }
void MCFillFragment::anchor() { }
@@ -1102,3 +1133,4 @@
void MCLEBFragment::anchor() { }
void MCDwarfLineAddrFragment::anchor() { }
void MCDwarfCallFrameFragment::anchor() { }
+