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[BOLT][Linux] Remove long-jump-labels option #120929

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[BOLT][Linux] Remove long-jump-labels option #120929

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18 changes: 9 additions & 9 deletions bolt/lib/Rewrite/LinuxKernelRewriter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -79,11 +79,6 @@ static cl::opt<bool>
cl::desc("dump Linux kernel static keys jump table"),
cl::init(false), cl::Hidden, cl::cat(BoltCategory));

static cl::opt<bool> LongJumpLabels(
"long-jump-labels",
cl::desc("always use long jumps/nops for Linux kernel static keys"),
cl::init(false), cl::Hidden, cl::cat(BoltCategory));

static cl::opt<bool>
PrintORC("print-orc",
cl::desc("print ORC unwind information for instructions"),
Expand Down Expand Up @@ -237,6 +232,9 @@ class LinuxKernelRewriter final : public MetadataRewriter {
/// Static key entries that need nop conversion.
DenseSet<uint32_t> NopIDs;

/// Use long jumps/nops for Linux kernel static keys.
bool LongJumpLabels{false};

/// Section containing static call table.
ErrorOr<BinarySection &> StaticCallSection = std::errc::bad_address;
uint64_t StaticCallTableAddress = 0;
Expand Down Expand Up @@ -351,6 +349,8 @@ class LinuxKernelRewriter final : public MetadataRewriter {
if (Error E = detectLinuxKernelVersion())
return E;

LongJumpLabels = LinuxKernelVersion < LKVersion(5, 14, 0);

processLKSections();

if (Error E = processSMPLocks())
Expand Down Expand Up @@ -1799,13 +1799,13 @@ Error LinuxKernelRewriter::readStaticKeysJumpTable() {
// the code, it will be converted to a different instruction in
// rewriteStaticKeysJumpTable().
//
// NB: for older kernels, under LongJumpLabels option, we create long
// NB: for older kernels (for which LongJumpLabels is true), we create long
// conditional branch to guarantee that code size estimation takes
// into account the extra bytes needed for long branch that will be used
// by the kernel patching code. Newer kernels can work with both short
// and long branches. The code for long conditional branch is larger
// than unconditional one, so we are pessimistic in our estimations.
if (opts::LongJumpLabels)
if (LongJumpLabels)
BC.MIB->createLongCondBranch(StaticKeyBranch, Target, 0, BC.Ctx.get());
else
BC.MIB->createCondBranch(StaticKeyBranch, Target, 0, BC.Ctx.get());
Expand All @@ -1832,7 +1832,7 @@ Error LinuxKernelRewriter::readStaticKeysJumpTable() {
if (!BC.MIB->getOffset(*Inst))
BC.MIB->setOffset(*Inst, JumpAddress - BF->getAddress());

if (opts::LongJumpLabels)
if (LongJumpLabels)
BC.MIB->setSize(*Inst, 5);
}

Expand Down Expand Up @@ -1879,7 +1879,7 @@ Error LinuxKernelRewriter::rewriteStaticKeysJumpTable() {
MCInst NewInst;
// Replace the instruction with unconditional jump even if it needs to
// be nop in the binary.
if (opts::LongJumpLabels) {
if (LongJumpLabels) {
BC.MIB->createLongUncondBranch(NewInst, Target, BC.Ctx.get());
} else {
// Newer kernels can handle short and long jumps for static keys.
Expand Down
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