================
@@ -2876,42 +2875,101 @@ void AsmPrinter::emitJumpTableInfo() {
MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 ||
MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference64,
F);
+
+ std::vector<unsigned> JumpTableIndices;
+ if (!TM.Options.EnableStaticDataPartitioning) {
+ for (unsigned JTI = 0, JTSize = JT.size(); JTI < JTSize; ++JTI)
+ JumpTableIndices.push_back(JTI);
+ emitJumpTables(JumpTableIndices, TLOF.getSectionForJumpTable(F, TM),
+ JTInDiffSection, *MJTI);
+ return;
+ }
+
+ // When static data partitioning is enabled, collect jump table entries that
+ // go into the same section together to reduce the amount of section switch
+ // statements.
+ //
+ // Iterate all jump tables, put hot jump table indices towards the beginning
+ // of the vector, and cold jump table indices towards the end. Meanwhile
+ // retain the relative orders of original jump tables within a hot or
unlikely
+ // section by reversing the cold jump table indices.
+ int NextHotJumpTableIndex = 0, NextColdJumpTableIndex = JT.size() - 1;
+ JumpTableIndices.resize(JT.size());
+ for (unsigned JTI = 0, JTSize = JT.size(); JTI < JTSize; ++JTI) {
+ if (JT[JTI].Hotness == MachineFunctionDataHotness::Cold)
+ JumpTableIndices[NextColdJumpTableIndex--] = JTI;
+ else
+ JumpTableIndices[NextHotJumpTableIndex++] = JTI;
+ }
+
+ if (NextHotJumpTableIndex != 0) {
+ emitJumpTables(
+ ArrayRef<unsigned>(JumpTableIndices).take_front(NextHotJumpTableIndex),
+ TLOF.getSectionForJumpTable(F, TM, &JT[0]), JTInDiffSection, *MJTI);
+ }
----------------
mingmingl-llvm wrote:
> ArrayRef::take_front(0) will return an empty array, and emitJumpTables()
> handles this case.
The updated change removed `if (NumHotJT>0)` and `if(NumColdJT)>0)` as
suggested.
In the original patch, they also gated the call to
`TLOF.getSectionForJumpTable(F, TM, &MJTE)`, so that a `MCSection` won't be
created if the number of JTs is zero.
In the updated patch, `emitJumpTableImpl` reads
`TM.Options.EnableStaticDataPartitioning` directly to call one of two
`getSectionForJumpTable` functions.
https://github.com/llvm/llvm-project/pull/122215
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