================
@@ -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);
+ }
+
+ if (NextHotJumpTableIndex < (int)JT.size()) {
+ // Reverse the order of cold jump tables indices.
+ for (int L = NextHotJumpTableIndex, R = JT.size() - 1; L < R; ++L, --R)
+ std::swap(JumpTableIndices[L], JumpTableIndices[R]);
+
+ emitJumpTables(
+ ArrayRef<unsigned>(JumpTableIndices)
+ .take_back(JT.size() - NextHotJumpTableIndex),
----------------
mingmingl-llvm wrote:
`drop_front` is clearer to me, despite `make_range` supersedes the ArrayRef
usage in the updated patch.
I became interested in why both `drop` and `take` exists, and it turns out
(amusingly) that `take_{front,back}`
[handles](https://github.com/llvm/llvm-project/blob/22d4ff155aadf0f098dd5dc48d9038da15108937/llvm/include/llvm/ADT/ArrayRef.h#L414-L426)
`N>=size()` by returning the full view while `drop_{front,back}`
[asserts](https://github.com/llvm/llvm-project/blob/22d4ff155aadf0f098dd5dc48d9038da15108937/llvm/include/llvm/ADT/ArrayRef.h#L389-L398)
`N <= size()` (and slices a bogus length otherwise).
https://github.com/llvm/llvm-project/pull/122215
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