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-rw-r--r--llvm/lib/MC/MCAssembler.cpp118
-rw-r--r--llvm/lib/MC/MCExpr.cpp10
-rw-r--r--llvm/lib/MC/MCFragment.cpp12
-rw-r--r--llvm/lib/MC/MCObjectStreamer.cpp5
-rw-r--r--llvm/lib/MC/MCStreamer.cpp2
-rw-r--r--llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp24
6 files changed, 126 insertions, 45 deletions
diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp
index ad30b5c..62baeb9 100644
--- a/llvm/lib/MC/MCAssembler.cpp
+++ b/llvm/lib/MC/MCAssembler.cpp
@@ -298,6 +298,43 @@ bool MCAssembler::evaluateFixup(const MCAsmLayout &Layout, const MCFixup &Fixup,
return IsResolved;
}
+/// Check if the branch crosses the boundary.
+///
+/// \param StartAddr start address of the fused/unfused branch.
+/// \param Size size of the fused/unfused branch.
+/// \param BoundaryAlignment alignment requirement of the branch.
+/// \returns true if the branch cross the boundary.
+static bool mayCrossBoundary(uint64_t StartAddr, uint64_t Size,
+ Align BoundaryAlignment) {
+ uint64_t EndAddr = StartAddr + Size;
+ return (StartAddr >> Log2(BoundaryAlignment)) !=
+ ((EndAddr - 1) >> Log2(BoundaryAlignment));
+}
+
+/// Check if the branch is against the boundary.
+///
+/// \param StartAddr start address of the fused/unfused branch.
+/// \param Size size of the fused/unfused branch.
+/// \param BoundaryAlignment alignment requirement of the branch.
+/// \returns true if the branch is against the boundary.
+static bool isAgainstBoundary(uint64_t StartAddr, uint64_t Size,
+ Align BoundaryAlignment) {
+ uint64_t EndAddr = StartAddr + Size;
+ return (EndAddr & (BoundaryAlignment.value() - 1)) == 0;
+}
+
+/// Check if the branch needs padding.
+///
+/// \param StartAddr start address of the fused/unfused branch.
+/// \param Size size of the fused/unfused branch.
+/// \param BoundaryAlignment alignment requirement of the branch.
+/// \returns true if the branch needs padding.
+static bool needPadding(uint64_t StartAddr, uint64_t Size,
+ Align BoundaryAlignment) {
+ return mayCrossBoundary(StartAddr, Size, BoundaryAlignment) ||
+ isAgainstBoundary(StartAddr, Size, BoundaryAlignment);
+}
+
uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout,
const MCFragment &F) const {
assert(getBackendPtr() && "Requires assembler backend");
@@ -358,6 +395,41 @@ uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout,
return Size;
}
+ case MCFragment::FT_NeverAlign: {
+ // Disclaimer: NeverAlign fragment size depends on the size of its immediate
+ // successor, but NeverAlign need not be a MCRelaxableFragment.
+ // NeverAlign fragment size is recomputed if the successor is relaxed:
+ // - If RelaxableFragment is relaxed, it gets invalidated by marking its
+ // predecessor as LastValidFragment.
+ // - This forces the assembler to call MCAsmLayout::layoutFragment on that
+ // relaxable fragment, which in turn will always ask the predecessor to
+ // compute its size (see "computeFragmentSize(prev)" in layoutFragment).
+ //
+ // In short, the simplest way to ensure that computeFragmentSize() is sane
+ // is to establish the following rule: it should never examine fragments
+ // after the current fragment in the section. If we logically need to
+ // examine any fragment after the current fragment, we need to do that using
+ // relaxation, inside MCAssembler::layoutSectionOnce.
+ const MCNeverAlignFragment &NAF = cast<MCNeverAlignFragment>(F);
+ const MCFragment *NF = F.getNextNode();
+ uint64_t Offset = Layout.getFragmentOffset(&NAF);
+ size_t NextFragSize = 0;
+ if (const auto *NextFrag = dyn_cast<MCRelaxableFragment>(NF)) {
+ NextFragSize = NextFrag->getContents().size();
+ } else if (const auto *NextFrag = dyn_cast<MCDataFragment>(NF)) {
+ NextFragSize = NextFrag->getContents().size();
+ } else {
+ llvm_unreachable("Didn't find the expected fragment after NeverAlign");
+ }
+ // Check if the next fragment ends at the alignment we want to avoid.
+ if (isAgainstBoundary(Offset, NextFragSize, Align(NAF.getAlignment()))) {
+ // Avoid this alignment by introducing minimum nop.
+ assert(getBackend().getMinimumNopSize() != NAF.getAlignment());
+ return getBackend().getMinimumNopSize();
+ }
+ return 0;
+ }
+
case MCFragment::FT_Org: {
const MCOrgFragment &OF = cast<MCOrgFragment>(F);
MCValue Value;
@@ -581,6 +653,15 @@ static void writeFragment(raw_ostream &OS, const MCAssembler &Asm,
break;
}
+ case MCFragment::FT_NeverAlign: {
+ const MCNeverAlignFragment &NAF = cast<MCNeverAlignFragment>(F);
+ if (!Asm.getBackend().writeNopData(OS, FragmentSize,
+ &NAF.getSubtargetInfo()))
+ report_fatal_error("unable to write nop sequence of " +
+ Twine(FragmentSize) + " bytes");
+ break;
+ }
+
case MCFragment::FT_Data:
++stats::EmittedDataFragments;
OS << cast<MCDataFragment>(F).getContents();
@@ -1052,43 +1133,6 @@ bool MCAssembler::relaxLEB(MCAsmLayout &Layout, MCLEBFragment &LF) {
return OldSize != LF.getContents().size();
}
-/// Check if the branch crosses the boundary.
-///
-/// \param StartAddr start address of the fused/unfused branch.
-/// \param Size size of the fused/unfused branch.
-/// \param BoundaryAlignment alignment requirement of the branch.
-/// \returns true if the branch cross the boundary.
-static bool mayCrossBoundary(uint64_t StartAddr, uint64_t Size,
- Align BoundaryAlignment) {
- uint64_t EndAddr = StartAddr + Size;
- return (StartAddr >> Log2(BoundaryAlignment)) !=
- ((EndAddr - 1) >> Log2(BoundaryAlignment));
-}
-
-/// Check if the branch is against the boundary.
-///
-/// \param StartAddr start address of the fused/unfused branch.
-/// \param Size size of the fused/unfused branch.
-/// \param BoundaryAlignment alignment requirement of the branch.
-/// \returns true if the branch is against the boundary.
-static bool isAgainstBoundary(uint64_t StartAddr, uint64_t Size,
- Align BoundaryAlignment) {
- uint64_t EndAddr = StartAddr + Size;
- return (EndAddr & (BoundaryAlignment.value() - 1)) == 0;
-}
-
-/// Check if the branch needs padding.
-///
-/// \param StartAddr start address of the fused/unfused branch.
-/// \param Size size of the fused/unfused branch.
-/// \param BoundaryAlignment alignment requirement of the branch.
-/// \returns true if the branch needs padding.
-static bool needPadding(uint64_t StartAddr, uint64_t Size,
- Align BoundaryAlignment) {
- return mayCrossBoundary(StartAddr, Size, BoundaryAlignment) ||
- isAgainstBoundary(StartAddr, Size, BoundaryAlignment);
-}
-
bool MCAssembler::relaxBoundaryAlign(MCAsmLayout &Layout,
MCBoundaryAlignFragment &BF) {
// BoundaryAlignFragment that doesn't need to align any fragment should not be
diff --git a/llvm/lib/MC/MCExpr.cpp b/llvm/lib/MC/MCExpr.cpp
index b065d03..9add574 100644
--- a/llvm/lib/MC/MCExpr.cpp
+++ b/llvm/lib/MC/MCExpr.cpp
@@ -675,14 +675,8 @@ static void AttemptToFoldSymbolOffsetDifference(
if (FA == FB) {
Reverse = SA.getOffset() < SB.getOffset();
} else if (!isa<MCDummyFragment>(FA)) {
- // Testing FA < FB is slow. Use setLayoutOrder to speed up computation.
- // The formal layout order will be finalized in MCAssembler::layout.
- if (FA->getLayoutOrder() == 0 || FB->getLayoutOrder()== 0) {
- unsigned LayoutOrder = 0;
- for (MCFragment &F : *FA->getParent())
- F.setLayoutOrder(++LayoutOrder);
- }
- Reverse = FA->getLayoutOrder() < FB->getLayoutOrder();
+ Reverse = std::find_if(std::next(FA->getIterator()), SecA.end(),
+ [&](auto &I) { return &I == FB; }) != SecA.end();
}
uint64_t SAOffset = SA.getOffset(), SBOffset = SB.getOffset();
diff --git a/llvm/lib/MC/MCFragment.cpp b/llvm/lib/MC/MCFragment.cpp
index 7d08268..6e09caa 100644
--- a/llvm/lib/MC/MCFragment.cpp
+++ b/llvm/lib/MC/MCFragment.cpp
@@ -274,6 +274,9 @@ void MCFragment::destroy() {
case FT_Align:
delete cast<MCAlignFragment>(this);
return;
+ case FT_NeverAlign:
+ delete cast<MCNeverAlignFragment>(this);
+ return;
case FT_Data:
delete cast<MCDataFragment>(this);
return;
@@ -342,6 +345,9 @@ LLVM_DUMP_METHOD void MCFragment::dump() const {
OS << "<";
switch (getKind()) {
case MCFragment::FT_Align: OS << "MCAlignFragment"; break;
+ case MCFragment::FT_NeverAlign:
+ OS << "MCNeverAlignFragment";
+ break;
case MCFragment::FT_Data: OS << "MCDataFragment"; break;
case MCFragment::FT_CompactEncodedInst:
OS << "MCCompactEncodedInstFragment"; break;
@@ -381,6 +387,12 @@ LLVM_DUMP_METHOD void MCFragment::dump() const {
<< " MaxBytesToEmit:" << AF->getMaxBytesToEmit() << ">";
break;
}
+ case MCFragment::FT_NeverAlign: {
+ const MCNeverAlignFragment *NAF = cast<MCNeverAlignFragment>(this);
+ OS << "\n ";
+ OS << " Alignment:" << NAF->getAlignment() << ">";
+ break;
+ }
case MCFragment::FT_Data: {
const auto *DF = cast<MCDataFragment>(this);
OS << "\n ";
diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
index 0ccade9..117475b 100644
--- a/llvm/lib/MC/MCObjectStreamer.cpp
+++ b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -658,6 +658,11 @@ void MCObjectStreamer::emitCodeAlignment(Align Alignment,
cast<MCAlignFragment>(getCurrentFragment())->setEmitNops(true, STI);
}
+void MCObjectStreamer::emitNeverAlignCodeAtEnd(unsigned ByteAlignment,
+ const MCSubtargetInfo &STI) {
+ insert(new MCNeverAlignFragment(ByteAlignment, STI));
+}
+
void MCObjectStreamer::emitValueToOffset(const MCExpr *Offset,
unsigned char Value,
SMLoc Loc) {
diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
index 199d865..a97cba6 100644
--- a/llvm/lib/MC/MCStreamer.cpp
+++ b/llvm/lib/MC/MCStreamer.cpp
@@ -1235,6 +1235,8 @@ void MCStreamer::emitValueToAlignment(Align Alignment, int64_t Value,
unsigned MaxBytesToEmit) {}
void MCStreamer::emitCodeAlignment(Align Alignment, const MCSubtargetInfo *STI,
unsigned MaxBytesToEmit) {}
+void MCStreamer::emitNeverAlignCodeAtEnd(unsigned ByteAlignment,
+ const MCSubtargetInfo &STI) {}
void MCStreamer::emitValueToOffset(const MCExpr *Offset, unsigned char Value,
SMLoc Loc) {}
void MCStreamer::emitBundleAlignMode(Align Alignment) {}
diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
index 6623106..6c6bd2c 100644
--- a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -1153,6 +1153,7 @@ private:
bool parseDirectiveArch();
bool parseDirectiveNops(SMLoc L);
bool parseDirectiveEven(SMLoc L);
+ bool parseDirectiveAvoidEndAlign(SMLoc L);
bool ParseDirectiveCode(StringRef IDVal, SMLoc L);
/// CodeView FPO data directives.
@@ -4601,6 +4602,8 @@ bool X86AsmParser::ParseDirective(AsmToken DirectiveID) {
return false;
} else if (IDVal == ".nops")
return parseDirectiveNops(DirectiveID.getLoc());
+ else if (IDVal == ".avoid_end_align")
+ return parseDirectiveAvoidEndAlign(DirectiveID.getLoc());
else if (IDVal == ".even")
return parseDirectiveEven(DirectiveID.getLoc());
else if (IDVal == ".cv_fpo_proc")
@@ -4695,6 +4698,27 @@ bool X86AsmParser::parseDirectiveEven(SMLoc L) {
return false;
}
+/// Directive for NeverAlign fragment testing, not for general usage!
+/// parseDirectiveAvoidEndAlign
+/// ::= .avoid_end_align alignment
+bool X86AsmParser::parseDirectiveAvoidEndAlign(SMLoc L) {
+ int64_t Alignment = 0;
+ SMLoc AlignmentLoc;
+ AlignmentLoc = getTok().getLoc();
+ if (getParser().checkForValidSection() ||
+ getParser().parseAbsoluteExpression(Alignment))
+ return true;
+
+ if (getParser().parseEOL("unexpected token in directive"))
+ return true;
+
+ if (Alignment <= 0)
+ return Error(AlignmentLoc, "expected a positive alignment");
+
+ getParser().getStreamer().emitNeverAlignCodeAtEnd(Alignment, getSTI());
+ return false;
+}
+
/// ParseDirectiveCode
/// ::= .code16 | .code32 | .code64
bool X86AsmParser::ParseDirectiveCode(StringRef IDVal, SMLoc L) {
generated by cgit v1.1 at 2025-09-27 15:42:06 +0000