Introduce a TargetMachine option , and the command line flag option to set it

Author: mingmingl-llvm

llvm/include/llvm/CodeGen/CommandFlags.h

@@ -136,6 +136,8 @@ bool getEmitCallSiteInfo();
 
 bool getEnableMachineFunctionSplitter();
 
+bool getEnableStaticDataPartitioning();
+
 bool getEnableDebugEntryValues();
 
 bool getValueTrackingVariableLocations();

llvm/include/llvm/Target/TargetMachine.h

@@ -305,6 +305,10 @@ class TargetMachine {
     return Options.FunctionSections;
   }
 
+  bool getEnableStaticDataPartitioning() const {
+    return Options.EnableStaticDataPartitioning;
+  }
+
   /// Return true if visibility attribute should not be emitted in XCOFF,
   /// corresponding to -mignore-xcoff-visibility.
   bool getIgnoreXCOFFVisibility() const {

llvm/include/llvm/Target/TargetOptions.h

@@ -312,6 +312,9 @@ namespace llvm {
     /// Enables the MachineFunctionSplitter pass.
     unsigned EnableMachineFunctionSplitter : 1;
 
+    /// Enables the StaticDataSplitter pass.
+    unsigned EnableStaticDataPartitioning : 1;
+
     /// Set if the target supports default outlining behaviour.
     unsigned SupportsDefaultOutlining : 1;
 

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -168,11 +168,6 @@ static cl::opt<bool> BBAddrMapSkipEmitBBEntries(
              "unnecessary for some PGOAnalysisMap features."),
     cl::Hidden, cl::init(false));
 
-static cl::opt<bool>
-    EmitStaticDataHotnessSuffix("emit-static-data-hotness-suffix", cl::Hidden,
-                                cl::init(false), cl::ZeroOrMore,
-                                cl::desc("Emit static data hotness suffix"));
-
 static cl::opt<bool> EmitJumpTableSizesSection(
     "emit-jump-table-sizes-section",
     cl::desc("Emit a section containing jump table addresses and sizes"),
@@ -2882,7 +2877,7 @@ void AsmPrinter::emitJumpTableInfo() {
       F);
 
   std::vector<unsigned> JumpTableIndices;
-  if (!EmitStaticDataHotnessSuffix) {
+  if (!TM.Options.EnableStaticDataPartitioning) {
     for (unsigned JTI = 0, JTSize = JT.size(); JTI < JTSize; ++JTI)
       JumpTableIndices.push_back(JTI);
     emitJumpTables(JumpTableIndices, TLOF.getSectionForJumpTable(F, TM),

llvm/lib/CodeGen/CommandFlags.cpp

@@ -103,6 +103,7 @@ CGOPT(bool, EnableStackSizeSection)
 CGOPT(bool, EnableAddrsig)
 CGOPT(bool, EmitCallSiteInfo)
 CGOPT(bool, EnableMachineFunctionSplitter)
+CGOPT(bool, EnableStaticDataPartitioning)
 CGOPT(bool, EnableDebugEntryValues)
 CGOPT(bool, ForceDwarfFrameSection)
 CGOPT(bool, XRayFunctionIndex)
@@ -480,6 +481,12 @@ codegen::RegisterCodeGenFlags::RegisterCodeGenFlags() {
       cl::init(false));
   CGBINDOPT(EnableMachineFunctionSplitter);
 
+  static cl::opt<bool> EnableStaticDataPartitioning(
+      "partition-static-data-sections",
+      cl::desc("Partition data sections using profile information."),
+      cl::init(false));
+  CGBINDOPT(EnableStaticDataPartitioning);
+
   static cl::opt<bool> ForceDwarfFrameSection(
       "force-dwarf-frame-section",
       cl::desc("Always emit a debug frame section."), cl::init(false));
@@ -586,6 +593,7 @@ codegen::InitTargetOptionsFromCodeGenFlags(const Triple &TheTriple) {
   Options.ExceptionModel = getExceptionModel();
   Options.EmitStackSizeSection = getEnableStackSizeSection();
   Options.EnableMachineFunctionSplitter = getEnableMachineFunctionSplitter();
+  Options.EnableStaticDataPartitioning = getEnableStaticDataPartitioning();
   Options.EmitAddrsig = getEnableAddrsig();
   Options.EmitCallSiteInfo = getEmitCallSiteInfo();
   Options.EnableDebugEntryValues = getEnableDebugEntryValues();

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -974,7 +974,7 @@ MCSection *TargetLoweringObjectFileELF::getSectionForJumpTable(
   // the table doesn't prevent the removal.
   const Comdat *C = F.getComdat();
   bool EmitUniqueSection = TM.getFunctionSections() || C;
-  if (!EmitUniqueSection)
+  if (!EmitUniqueSection && !TM.getEnableStaticDataPartitioning())
     return ReadOnlySection;
 
   return selectELFSectionForGlobal(getContext(), &F, SectionKind::getReadOnly(),

llvm/lib/CodeGen/TargetPassConfig.cpp

@@ -1261,7 +1261,7 @@ void TargetPassConfig::addMachinePasses() {
                "performance.\n";
       }
     }
-    if (SplitStaticData)
+    if (SplitStaticData || TM->Options.EnableStaticDataPartitioning)
       addPass(createStaticDataSplitterPass());
     addPass(createMachineFunctionSplitterPass());
   }

llvm/test/CodeGen/X86/jump-table-partition.ll

@@ -6,22 +6,36 @@
 ; RUN: llc -stop-after=finalize-isel -min-jump-table-entries=2 %s -o %t.mir
 ; RUN: llc --run-pass=static-data-splitter -stats -x mir %t.mir -o - 2>&1 | FileCheck %s --check-prefix=STAT
 
-; RUN: llc -enable-split-machine-functions -split-static-data -emit-static-data-hotness-suffix=true -function-sections -min-jump-table-entries=2 -disable-block-placement %s -o - 2>&1 | FileCheck %s --check-prefix=SECTION
-
-; Tests stat messages are expected.
-; TODO: Update test to verify section suffixes when target-lowering and assembler changes are implemented.
-; TODO: Also run static-data-splitter pass with -static-data-default-hotness=cold and check data section suffix.
+; When 'partition-static-data-sections' is enabled, static data splitter pass will
+; categorize jump tables and assembly printer will place hot jump tables in the
+; `.hot`-suffixed read only section, and cold ones in the `.rodata` sections.
+; Section names will optionally have `.<func>` if -function-sections is enabled.
+; RUN: llc -enable-split-machine-functions -partition-static-data-sections=true -function-sections=true -min-jump-table-entries=2  %s -o - 2>&1 | FileCheck %s --check-prefixes=FUNC,JT,HOT
+; RUN: llc -enable-split-machine-functions -partition-static-data-sections=true -function-sections=false -min-jump-table-entries=2 %s -o - 2>&1 | FileCheck %s --check-prefixes=FUNCLESS,JT
+
+; Tests that jump tables with unknown hotness are categorized as cold if `-static-data-default-hotness` specifies so.
+; RUN: llc -enable-split-machine-functions -partition-static-data-sections=true -min-jump-table-entries=2 -static-data-default-hotness=cold -function-sections=true %s -o - 2>&1 | FileCheck %s --check-prefixes=FUNC,JT,DEFAULT
 
+ ; Tests stat messages are expected.
 ; STAT-DAG: 2 static-data-splitter - Number of cold jump tables seen
-; STAT-DAG: 3 static-data-splitter - Number of hot jump tables seen
+; STAT-DAG: 2 static-data-splitter - Number of hot jump tables seen
 ; STAT-DAG: 1 static-data-splitter - Number of jump tables with unknown hotness
 
-; SECTION: .section .rodata.hot.foo,"a",@progbits
-; SECTION: .LJTI0_0:
-; SECTION: .LJTI0_2:
-; SECTION: .section .rodata.foo,"a",@progbits
-; SECTION: .LJTI0_1:
-; SECTION: .LJTI0_3:
+; Tests that the first and third jump table are placed in a hot-suffixed section,
+; and the second and fourth are placed in the original section.
+; FUNC: .section .rodata.hot.foo,"a",@progbits
+; FUNCLESS: .section .rodata.hot,"a",@progbits
+; JT: .LJTI0_0:
+; JT: .LJTI0_2:
+; FUNC: .section .rodata.foo,"a",@progbits
+; FUNCLESS: .section .rodata,"a",@progbits
+; JT: .LJTI0_1:
+; JT: .LJTI0_3:
+; HOT: .section .rodata.hot.func_without_entry_count,"a",@progbits
+; HOT: .LJTI1_0:
+
+; DEFAULT: .section .rodata.func_without_entry_count,"a",@progbits
+; DEFAULT: .LJTI1_0:
 
 ; @foo has four jump tables, jt0, jt1, jt2 and jt3 in the input basic block
 ; order; jt0 and jt2 are hot, and jt1 and jt3 are cold.
@@ -142,42 +156,6 @@ return:
   ret i32 %mod3
 }
 
-define i32 @func_with_hot_jt() !prof !15 {
-entry:
-  br label %for.body
-
-for.cond.cleanup:
-  ret i32 0
-
-for.body:
-  %lsr.iv = phi i32 [ 100000, %entry ], [ %lsr.iv.next, %loop.exit ]
-  %i.04 = phi i32 [ 0, %entry ], [ %inc, %loop.exit ]
-  %0 = urem i32 %i.04, 100
-  switch i32 %0, label %sw.default [
-    i32 1, label %loop.exit
-    i32 2, label %sw.bb1.i
-    i32 3, label %sw.bb3.i
-  ], !prof !19
-
-sw.bb1.i:
-  br label %loop.exit
-
-sw.bb3.i: 
-  call i32 (ptr, ...) @printf(ptr @case1)
-  br label %sw.default
-
-sw.default:
-  br label %loop.exit
-
-loop.exit:
-  %str.5.sink.i = phi ptr [ @str.10, %sw.default ], [ @str.9, %sw.bb1.i ], [ @case2, %for.body ]
-  call i32 @puts(ptr %str.5.sink.i)
-  %inc = add i32 %i.04, 1
-  %lsr.iv.next = add i32 %lsr.iv, -1
-  %exitcond.not = icmp eq i32 %lsr.iv.next, 0
-  br i1 %exitcond.not, label %for.body, label %for.cond.cleanup, !prof !17
-}
-
 define void @func_without_entry_count(i32 %num) {
 entry:
   switch i32 %num, label %sw.default [