[llvm-branch-commits] [llvm] [NFC][AsmPrinter] Refactor AsmPrinter and AArch64AsmPrinter to prepare for jump table partitions on aarch64 (PR #125993)
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llvm-branch-commits at lists.llvm.org
Wed Feb 5 22:37:39 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-aarch64
Author: Mingming Liu (mingmingl-llvm)
<details>
<summary>Changes</summary>
With https://github.com/llvm/llvm-project/commit/3feb724496238ce10d32e8c2bd84b4ea50f9977e, AsmPrinter can place jump table entries into `.hot` or `.unlikely` prefixed data sections. This change refactors AsmPrinter and AArch64AsmPrinter to prepare for the aarch64 port.
* Before this patch, the AsmPrinter class exposes `emitJumpTableInfo` as a virtual method, and AArch64AsmPrinter overrides `emitJumpTableInfo` for jump table emission.
* After this patch, both AsmPrinter and AArch64AsmPrinter shares `AsmPrinter::emitJumpTableInfo`, and class-specific code are moved inside `emitJumpTableImpl` respectively.
This is a follow-up of https://github.com/llvm/llvm-project/pull/125987
---
Full diff: https://github.com/llvm/llvm-project/pull/125993.diff
4 Files Affected:
- (modified) llvm/include/llvm/CodeGen/AsmPrinter.h (+2-3)
- (modified) llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp (+21-25)
- (modified) llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp (+9-9)
- (modified) llvm/test/CodeGen/AArch64/jump-table-partition.ll (+11-8)
``````````diff
diff --git a/llvm/include/llvm/CodeGen/AsmPrinter.h b/llvm/include/llvm/CodeGen/AsmPrinter.h
index 3da63af5ba5716c..9ef9888af990c63 100644
--- a/llvm/include/llvm/CodeGen/AsmPrinter.h
+++ b/llvm/include/llvm/CodeGen/AsmPrinter.h
@@ -893,9 +893,8 @@ class AsmPrinter : public MachineFunctionPass {
// Internal Implementation Details
//===------------------------------------------------------------------===//
- void emitJumpTableImpl(const MachineJumpTableInfo &MJTI,
- ArrayRef<unsigned> JumpTableIndices,
- bool JTInDiffSection);
+ virtual void emitJumpTableImpl(const MachineJumpTableInfo &MJTI,
+ ArrayRef<unsigned> JumpTableIndices);
void emitJumpTableEntry(const MachineJumpTableInfo &MJTI,
const MachineBasicBlock *MBB, unsigned uid) const;
diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 44b10c3ef997267..07fe589fcbbd065 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -2855,22 +2855,12 @@ void AsmPrinter::emitConstantPool() {
void AsmPrinter::emitJumpTableInfo() {
const MachineJumpTableInfo *MJTI = MF->getJumpTableInfo();
if (!MJTI) return;
- if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_Inline) return;
+
const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
if (JT.empty()) return;
- // Pick the directive to use to print the jump table entries, and switch to
- // the appropriate section.
- const Function &F = MF->getFunction();
- const TargetLoweringObjectFile &TLOF = getObjFileLowering();
- bool JTInDiffSection = !TLOF.shouldPutJumpTableInFunctionSection(
- MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 ||
- MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference64,
- F);
-
if (!TM.Options.EnableStaticDataPartitioning) {
- emitJumpTableImpl(*MJTI, llvm::to_vector(llvm::seq<unsigned>(JT.size())),
- JTInDiffSection);
+ emitJumpTableImpl(*MJTI, llvm::to_vector(llvm::seq<unsigned>(JT.size())));
return;
}
@@ -2886,33 +2876,39 @@ void AsmPrinter::emitJumpTableInfo() {
}
}
- emitJumpTableImpl(*MJTI, HotJumpTableIndices, JTInDiffSection);
- emitJumpTableImpl(*MJTI, ColdJumpTableIndices, JTInDiffSection);
+ emitJumpTableImpl(*MJTI, HotJumpTableIndices);
+ emitJumpTableImpl(*MJTI, ColdJumpTableIndices);
}
void AsmPrinter::emitJumpTableImpl(const MachineJumpTableInfo &MJTI,
- ArrayRef<unsigned> JumpTableIndices,
- bool JTInDiffSection) {
- if (JumpTableIndices.empty())
+ ArrayRef<unsigned> JumpTableIndices) {
+ if (MJTI.getEntryKind() == MachineJumpTableInfo::EK_Inline ||
+ JumpTableIndices.empty())
return;
const TargetLoweringObjectFile &TLOF = getObjFileLowering();
const Function &F = MF->getFunction();
const std::vector<MachineJumpTableEntry> &JT = MJTI.getJumpTables();
MCSection *JumpTableSection = nullptr;
- if (TM.Options.EnableStaticDataPartitioning) {
- JumpTableSection =
- TLOF.getSectionForJumpTable(F, TM, &JT[JumpTableIndices.front()]);
- } else {
- JumpTableSection = TLOF.getSectionForJumpTable(F, TM);
- }
- const DataLayout &DL = MF->getDataLayout();
+ // Pick the directive to use to print the jump table entries, and switch to
+ // the appropriate section.
+ const bool JTInDiffSection = !TLOF.shouldPutJumpTableInFunctionSection(
+ MJTI.getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 ||
+ MJTI.getEntryKind() == MachineJumpTableInfo::EK_LabelDifference64,
+ F);
if (JTInDiffSection) {
+ if (TM.Options.EnableStaticDataPartitioning) {
+ JumpTableSection =
+ TLOF.getSectionForJumpTable(F, TM, &JT[JumpTableIndices.front()]);
+ } else {
+ JumpTableSection = TLOF.getSectionForJumpTable(F, TM);
+ }
OutStreamer->switchSection(JumpTableSection);
}
- emitAlignment(Align(MJTI.getEntryAlignment(MF->getDataLayout())));
+ const DataLayout &DL = MF->getDataLayout();
+ emitAlignment(Align(MJTI.getEntryAlignment(DL)));
// Jump tables in code sections are marked with a data_region directive
// where that's supported.
diff --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
index f1f25b65fc53fac..c92c203f247954b 100644
--- a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -112,7 +112,8 @@ class AArch64AsmPrinter : public AsmPrinter {
const MCExpr *lowerBlockAddressConstant(const BlockAddress &BA) override;
void emitStartOfAsmFile(Module &M) override;
- void emitJumpTableInfo() override;
+ void emitJumpTableImpl(const MachineJumpTableInfo &MJTI,
+ ArrayRef<unsigned> JumpTableIndices) override;
std::tuple<const MCSymbol *, uint64_t, const MCSymbol *,
codeview::JumpTableEntrySize>
getCodeViewJumpTableInfo(int JTI, const MachineInstr *BranchInstr,
@@ -1273,19 +1274,18 @@ void AArch64AsmPrinter::PrintDebugValueComment(const MachineInstr *MI,
printOperand(MI, NOps - 2, OS);
}
-void AArch64AsmPrinter::emitJumpTableInfo() {
- const MachineJumpTableInfo *MJTI = MF->getJumpTableInfo();
- if (!MJTI) return;
-
- const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
- if (JT.empty()) return;
-
+void AArch64AsmPrinter::emitJumpTableImpl(const MachineJumpTableInfo &MJTI,
+ ArrayRef<unsigned> JumpTableIndices) {
+ // Fast return if there is nothing to emit to avoid creating empty sections.
+ if (JumpTableIndices.empty())
+ return;
const TargetLoweringObjectFile &TLOF = getObjFileLowering();
MCSection *ReadOnlySec = TLOF.getSectionForJumpTable(MF->getFunction(), TM);
OutStreamer->switchSection(ReadOnlySec);
+ const std::vector<MachineJumpTableEntry> &JT = MJTI.getJumpTables();
auto AFI = MF->getInfo<AArch64FunctionInfo>();
- for (unsigned JTI = 0, e = JT.size(); JTI != e; ++JTI) {
+ for (unsigned JTI : JumpTableIndices) {
const std::vector<MachineBasicBlock*> &JTBBs = JT[JTI].MBBs;
// If this jump table was deleted, ignore it.
diff --git a/llvm/test/CodeGen/AArch64/jump-table-partition.ll b/llvm/test/CodeGen/AArch64/jump-table-partition.ll
index 122bbaef09185a2..e0525d0384a978e 100644
--- a/llvm/test/CodeGen/AArch64/jump-table-partition.ll
+++ b/llvm/test/CodeGen/AArch64/jump-table-partition.ll
@@ -37,26 +37,29 @@
; A function's section prefix is used for all jump tables of this function.
; @foo is hot so its jump table data section has a hot prefix.
-; NUM: .section .rodata.hot.,"a", at progbits,unique,2
+; NUM: .section .rodata.hot.,"a", at progbits,unique,2
; FUNC: .section .rodata.hot.foo,"a", at progbits
; FUNCLESS: .section .rodata.hot.,"a", at progbits
; JT: .LJTI0_0:
-; JT: .LJTI0_1:
; JT: .LJTI0_2:
+; NUM: .section .rodata.hot.,"a", at progbits,unique,3
+; FUNC-NOT: .section .rodata.hot.foo
+; FUNCLESS-NOT: .section .rodata.hot.,"a", at progbits
+; JT: .LJTI0_1:
; JT: .LJTI0_3:
; func_without_profile doesn't have profiles, so its jumptable doesn't have
; hotness-based prefix.
-; NUM: .section .rodata,"a", at progbits,unique,4
-; FUNC: .section .rodata.func_without_profile,"a", at progbits
-; FUNCLESS: .section .rodata,"a", at progbits
+; NUM: .section .rodata,"a", at progbits,unique,5
+; FUNC: .section .rodata.func_without_profile,"a", at progbits
+; FUNCLESS: .section .rodata,"a", at progbits
; JT: .LJTI1_0:
; @bar doesn't have profile information and it has a section prefix.
; Tests that its jump tables are placed in sections with function prefixes.
-; NUM: .section .rodata.bar_prefix.,"a", at progbits,unique,
-; FUNC: .section .rodata.bar_prefix.bar
-; FUNCLESS: .section .rodata.bar_prefix.,"a"
+; NUM: .section .rodata.bar_prefix.,"a", at progbits,unique,7
+; FUNC: .section .rodata.bar_prefix.bar
+; FUNCLESS: .section .rodata.bar_prefix.,"a"
; JT: .LJTI2_0
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
``````````
</details>
https://github.com/llvm/llvm-project/pull/125993
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