diff options
Diffstat (limited to 'llvm/lib/MC/MCAssembler.cpp')
-rw-r--r-- | llvm/lib/MC/MCAssembler.cpp | 127 |
1 files changed, 57 insertions, 70 deletions
diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp index bcfda26..8582d51 100644 --- a/llvm/lib/MC/MCAssembler.cpp +++ b/llvm/lib/MC/MCAssembler.cpp @@ -285,6 +285,43 @@ bool MCAssembler::evaluateFixup(const MCAsmLayout &Layout, 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"); @@ -314,8 +351,26 @@ uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout, case MCFragment::FT_LEB: return cast<MCLEBFragment>(F).getContents().size(); - case MCFragment::FT_BoundaryAlign: - return cast<MCBoundaryAlignFragment>(F).getSize(); + case MCFragment::FT_BoundaryAlign: { + const MCBoundaryAlignFragment &BF = cast<MCBoundaryAlignFragment>(F); + // MCBoundaryAlignFragment that doesn't emit NOP should have 0 size. + if (!BF.canEmitNops()) + return 0; + + uint64_t AlignedOffset = Layout.getFragmentOffset(&BF); + uint64_t AlignedSize = 0; + const MCFragment *F = BF.getNextNode(); + // If the branch is unfused, it is emitted into one fragment, otherwise it + // is emitted into two fragments at most, the next + // MCBoundaryAlignFragment(if exists) also marks the end of the branch. + for (int I = 0, N = BF.isFused() ? 2 : 1; + I != N && !isa<MCBoundaryAlignFragment>(F); ++I, F = F->getNextNode()) + AlignedSize += computeFragmentSize(Layout, *F); + Align BoundaryAlignment = BF.getAlignment(); + return needPadding(AlignedOffset, AlignedSize, BoundaryAlignment) + ? offsetToAlignment(AlignedOffset, BoundaryAlignment) + : 0U; + } case MCFragment::FT_SymbolId: return 4; @@ -957,72 +1012,6 @@ 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) { - // The MCBoundaryAlignFragment that doesn't emit NOP should not be relaxed. - if (!BF.canEmitNops()) - return false; - - uint64_t AlignedOffset = Layout.getFragmentOffset(BF.getNextNode()); - uint64_t AlignedSize = 0; - const MCFragment *F = BF.getNextNode(); - // If the branch is unfused, it is emitted into one fragment, otherwise it is - // emitted into two fragments at most, the next MCBoundaryAlignFragment(if - // exists) also marks the end of the branch. - for (auto i = 0, N = BF.isFused() ? 2 : 1; - i != N && !isa<MCBoundaryAlignFragment>(F); ++i, F = F->getNextNode()) { - AlignedSize += computeFragmentSize(Layout, *F); - } - uint64_t OldSize = BF.getSize(); - AlignedOffset -= OldSize; - Align BoundaryAlignment = BF.getAlignment(); - uint64_t NewSize = needPadding(AlignedOffset, AlignedSize, BoundaryAlignment) - ? offsetToAlignment(AlignedOffset, BoundaryAlignment) - : 0U; - if (NewSize == OldSize) - return false; - BF.setSize(NewSize); - Layout.invalidateFragmentsFrom(&BF); - return true; -} - bool MCAssembler::relaxDwarfLineAddr(MCAsmLayout &Layout, MCDwarfLineAddrFragment &DF) { MCContext &Context = Layout.getAssembler().getContext(); @@ -1123,8 +1112,6 @@ bool MCAssembler::relaxFragment(MCAsmLayout &Layout, MCFragment &F) { cast<MCDwarfCallFrameFragment>(F)); case MCFragment::FT_LEB: return relaxLEB(Layout, cast<MCLEBFragment>(F)); - case MCFragment::FT_BoundaryAlign: - return relaxBoundaryAlign(Layout, cast<MCBoundaryAlignFragment>(F)); case MCFragment::FT_CVInlineLines: return relaxCVInlineLineTable(Layout, cast<MCCVInlineLineTableFragment>(F)); case MCFragment::FT_CVDefRange: |