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Diffstat (limited to 'contrib/llvm/lib/Target/ARM/ARMBasicBlockInfo.h')
-rw-r--r-- | contrib/llvm/lib/Target/ARM/ARMBasicBlockInfo.h | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Target/ARM/ARMBasicBlockInfo.h b/contrib/llvm/lib/Target/ARM/ARMBasicBlockInfo.h new file mode 100644 index 0000000..780544f --- /dev/null +++ b/contrib/llvm/lib/Target/ARM/ARMBasicBlockInfo.h @@ -0,0 +1,110 @@ +//===-- ARMBasicBlockInfo.h - Basic Block Information -----------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// Utility functions and data structure for computing block size. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_LIB_TARGET_ARM_ARMBASICBLOCKINFO_H +#define LLVM_LIB_TARGET_ARM_ARMBASICBLOCKINFO_H + +#include "ARM.h" +#include "ARMMachineFunctionInfo.h" +using namespace llvm; + +namespace llvm { + +/// UnknownPadding - Return the worst case padding that could result from +/// unknown offset bits. This does not include alignment padding caused by +/// known offset bits. +/// +/// @param LogAlign log2(alignment) +/// @param KnownBits Number of known low offset bits. +inline unsigned UnknownPadding(unsigned LogAlign, unsigned KnownBits) { + if (KnownBits < LogAlign) + return (1u << LogAlign) - (1u << KnownBits); + return 0; +} + +/// BasicBlockInfo - Information about the offset and size of a single +/// basic block. +struct BasicBlockInfo { + /// Offset - Distance from the beginning of the function to the beginning + /// of this basic block. + /// + /// Offsets are computed assuming worst case padding before an aligned + /// block. This means that subtracting basic block offsets always gives a + /// conservative estimate of the real distance which may be smaller. + /// + /// Because worst case padding is used, the computed offset of an aligned + /// block may not actually be aligned. + unsigned Offset; + + /// Size - Size of the basic block in bytes. If the block contains + /// inline assembly, this is a worst case estimate. + /// + /// The size does not include any alignment padding whether from the + /// beginning of the block, or from an aligned jump table at the end. + unsigned Size; + + /// KnownBits - The number of low bits in Offset that are known to be + /// exact. The remaining bits of Offset are an upper bound. + uint8_t KnownBits; + + /// Unalign - When non-zero, the block contains instructions (inline asm) + /// of unknown size. The real size may be smaller than Size bytes by a + /// multiple of 1 << Unalign. + uint8_t Unalign; + + /// PostAlign - When non-zero, the block terminator contains a .align + /// directive, so the end of the block is aligned to 1 << PostAlign + /// bytes. + uint8_t PostAlign; + + BasicBlockInfo() : Offset(0), Size(0), KnownBits(0), Unalign(0), + PostAlign(0) {} + + /// Compute the number of known offset bits internally to this block. + /// This number should be used to predict worst case padding when + /// splitting the block. + unsigned internalKnownBits() const { + unsigned Bits = Unalign ? Unalign : KnownBits; + // If the block size isn't a multiple of the known bits, assume the + // worst case padding. + if (Size & ((1u << Bits) - 1)) + Bits = countTrailingZeros(Size); + return Bits; + } + + /// Compute the offset immediately following this block. If LogAlign is + /// specified, return the offset the successor block will get if it has + /// this alignment. + unsigned postOffset(unsigned LogAlign = 0) const { + unsigned PO = Offset + Size; + unsigned LA = std::max(unsigned(PostAlign), LogAlign); + if (!LA) + return PO; + // Add alignment padding from the terminator. + return PO + UnknownPadding(LA, internalKnownBits()); + } + + /// Compute the number of known low bits of postOffset. If this block + /// contains inline asm, the number of known bits drops to the + /// instruction alignment. An aligned terminator may increase the number + /// of know bits. + /// If LogAlign is given, also consider the alignment of the next block. + unsigned postKnownBits(unsigned LogAlign = 0) const { + return std::max(std::max(unsigned(PostAlign), LogAlign), + internalKnownBits()); + } +}; + +} // end namespace llvm + +#endif |