[llvm] r194108 - Get rid of current calculation function and adjustment scheme
Reed Kotler
rkotler at mips.com
Tue Nov 5 15:36:58 PST 2013
Author: rkotler
Date: Tue Nov 5 17:36:58 2013
New Revision: 194108
URL: http://llvm.org/viewvc/llvm-project?rev=194108&view=rev
Log:
Get rid of current calculation function and adjustment scheme
from MipsConstantIslands.
Modified:
llvm/trunk/lib/Target/Mips/MipsConstantIslandPass.cpp
Modified: llvm/trunk/lib/Target/Mips/MipsConstantIslandPass.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Mips/MipsConstantIslandPass.cpp?rev=194108&r1=194107&r2=194108&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Mips/MipsConstantIslandPass.cpp (original)
+++ llvm/trunk/lib/Target/Mips/MipsConstantIslandPass.cpp Tue Nov 5 17:36:58 2013
@@ -66,17 +66,6 @@ static cl::opt<int> ConstantIslandsSmall
cl::desc("Make small offsets be this amount for testing purposes"),
cl::Hidden);
-/// 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.
-static inline unsigned UnknownPadding(unsigned LogAlign, unsigned KnownBits) {
- if (KnownBits < LogAlign)
- return (1u << LogAlign) - (1u << KnownBits);
- return 0;
-}
namespace {
@@ -119,52 +108,15 @@ namespace {
/// 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.
+ // FIXME: ignore LogAlign for this patch
+ //
unsigned postOffset(unsigned LogAlign = 0) const {
unsigned PO = Offset + Size;
return PO;
}
- /// 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());
- }
+ BasicBlockInfo() : Offset(0), Size(0) {}
+
};
std::vector<BasicBlockInfo> BBInfo;
@@ -203,25 +155,22 @@ namespace {
unsigned LongFormOpcode;
public:
bool NegOk;
- bool KnownAlignment;
CPUser(MachineInstr *mi, MachineInstr *cpemi, unsigned maxdisp,
bool neg,
unsigned longformmaxdisp, unsigned longformopcode)
: MI(mi), CPEMI(cpemi), MaxDisp(maxdisp),
LongFormMaxDisp(longformmaxdisp), LongFormOpcode(longformopcode),
- NegOk(neg), KnownAlignment(false) {
+ NegOk(neg){
HighWaterMark = CPEMI->getParent();
}
/// getMaxDisp - Returns the maximum displacement supported by MI.
- /// Correct for unknown alignment.
- /// Conservatively subtract 2 bytes to handle weird alignment effects.
unsigned getMaxDisp() const {
unsigned xMaxDisp = ConstantIslandsSmallOffset?
ConstantIslandsSmallOffset: MaxDisp;
- return (KnownAlignment ? xMaxDisp : xMaxDisp - 2) - 2;
+ return xMaxDisp;
}
unsigned getLongFormMaxDisp() const {
- return (KnownAlignment ? LongFormMaxDisp : LongFormMaxDisp - 2) - 2;
+ return LongFormMaxDisp;
}
unsigned getLongFormOpcode() const {
return LongFormOpcode;
@@ -377,9 +326,6 @@ void MipsConstantIslands::dumpBBs() {
for (unsigned J = 0, E = BBInfo.size(); J !=E; ++J) {
const BasicBlockInfo &BBI = BBInfo[J];
dbgs() << format("%08x BB#%u\t", BBI.Offset, J)
- << " kb=" << unsigned(BBI.KnownBits)
- << " ua=" << unsigned(BBI.Unalign)
- << " pa=" << unsigned(BBI.PostAlign)
<< format(" size=%#x\n", BBInfo[J].Size);
}
});
@@ -609,9 +555,6 @@ initializeFunctionInfo(const std::vector
for (MachineFunction::iterator I = MF->begin(), E = MF->end(); I != E; ++I)
computeBlockSize(I);
- // The known bits of the entry block offset are determined by the function
- // alignment.
- BBInfo.front().KnownBits = MF->getAlignment();
// Compute block offsets.
adjustBBOffsetsAfter(MF->begin());
@@ -708,8 +651,6 @@ initializeFunctionInfo(const std::vector
void MipsConstantIslands::computeBlockSize(MachineBasicBlock *MBB) {
BasicBlockInfo &BBI = BBInfo[MBB->getNumber()];
BBI.Size = 0;
- BBI.Unalign = 0;
- BBI.PostAlign = 0;
for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
++I)
@@ -892,7 +833,7 @@ bool MipsConstantIslands::isWaterInRange
// the offset of the instruction. Also account for unknown alignment padding
// in blocks between CPE and the user.
if (CPEOffset < UserOffset)
- UserOffset += Growth + UnknownPadding(MF->getAlignment(), CPELogAlign);
+ UserOffset += Growth;
} else
// CPE fits in existing padding.
Growth = 0;
@@ -945,7 +886,7 @@ void MipsConstantIslands::adjustBBOffset
for(unsigned i = BBNum + 1, e = MF->getNumBlockIDs(); i < e; ++i) {
// Get the offset and known bits at the end of the layout predecessor.
// Include the alignment of the current block.
- unsigned Offset = BBInfo[i - 1].postOffset();
+ unsigned Offset = BBInfo[i - 1].Offset + BBInfo[i - 1].Size;
BBInfo[i].Offset = Offset;
}
}
@@ -1183,9 +1124,7 @@ void MipsConstantIslands::createNewWater
// LogAlign which is the largest possible alignment in the function.
unsigned LogAlign = MF->getAlignment();
assert(LogAlign >= CPELogAlign && "Over-aligned constant pool entry");
- unsigned KnownBits = UserBBI.internalKnownBits();
- unsigned UPad = UnknownPadding(LogAlign, KnownBits);
- unsigned BaseInsertOffset = UserOffset + U.getMaxDisp() - UPad;
+ unsigned BaseInsertOffset = UserOffset + U.getMaxDisp();
DEBUG(dbgs() << format("Split in middle of big block before %#x",
BaseInsertOffset));
@@ -1195,19 +1134,17 @@ void MipsConstantIslands::createNewWater
BaseInsertOffset -= 4;
DEBUG(dbgs() << format(", adjusted to %#x", BaseInsertOffset)
- << " la=" << LogAlign
- << " kb=" << KnownBits
- << " up=" << UPad << '\n');
+ << " la=" << LogAlign << '\n');
// This could point off the end of the block if we've already got constant
// pool entries following this block; only the last one is in the water list.
// Back past any possible branches (allow for a conditional and a maximally
// long unconditional).
if (BaseInsertOffset + 8 >= UserBBI.postOffset()) {
- BaseInsertOffset = UserBBI.postOffset() - UPad - 8;
+ BaseInsertOffset = UserBBI.postOffset() - 8;
DEBUG(dbgs() << format("Move inside block: %#x\n", BaseInsertOffset));
}
- unsigned EndInsertOffset = BaseInsertOffset + 4 + UPad +
+ unsigned EndInsertOffset = BaseInsertOffset + 4 +
CPEMI->getOperand(2).getImm();
MachineBasicBlock::iterator MI = UserMI;
++MI;
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