1 files changed, 47 insertions, 0 deletions
diff --git a/lib/Target/Hexagon/HexagonTargetObjectFile.cpp b/lib/Target/Hexagon/HexagonTargetObjectFile.cpp
index 34df2ebcc5206..ea86c9c42f478 100644
--- a/lib/Target/Hexagon/HexagonTargetObjectFile.cpp
+++ b/lib/Target/Hexagon/HexagonTargetObjectFile.cpp
@@ -53,6 +53,10 @@ static cl::opt<bool>
     EmitJtInText("hexagon-emit-jt-text", cl::Hidden, cl::init(false),
                  cl::desc("Emit hexagon jump tables in function section"));
 
+static cl::opt<bool>
+    EmitLutInText("hexagon-emit-lut-text", cl::Hidden, cl::init(false),
+                 cl::desc("Emit hexagon lookup tables in function section"));
+
 // TraceGVPlacement controls messages for all builds. For builds with assertions
 // (debug or release), messages are also controlled by the usual debug flags
 // (e.g. -debug and -debug-only=globallayout)
@@ -136,6 +140,13 @@ MCSection *HexagonTargetObjectFile::SelectSectionForGlobal(
          << (Kind.isBSS() ? "kind_bss " : "" )
          << (Kind.isBSSLocal() ? "kind_bss_local " : "" ));
 
+  // If the lookup table is used by more than one function, do not place
+  // it in text section.
+  if (EmitLutInText && GO->getName().startswith("switch.table")) {
+    if (const Function *Fn = getLutUsedFunction(GO))
+      return selectSectionForLookupTable(GO, TM, Fn);
+  }
+
   if (isGlobalInSmallSection(GO, TM))
     return selectSmallSectionForGlobal(GO, Kind, TM);
 
@@ -402,3 +413,39 @@ MCSection *HexagonTargetObjectFile::selectSmallSectionForGlobal(
   // Otherwise, we work the same as ELF.
   return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM);
 }
+
+// Return the function that uses the lookup table. If there are more
+// than one live function that uses this look table, bail out and place
+// the lookup table in default section.
+const Function *
+HexagonTargetObjectFile::getLutUsedFunction(const GlobalObject *GO) const {
+  const Function *ReturnFn = nullptr;
+  for (auto U : GO->users()) {
+    // validate each instance of user to be a live function.
+    auto *I = dyn_cast<Instruction>(U);
+    if (!I)
+      continue;
+    auto *Bb = I->getParent();
+    if (!Bb)
+      continue;
+    auto *UserFn = Bb->getParent();
+    if (!ReturnFn)
+      ReturnFn = UserFn;
+    else if (ReturnFn != UserFn)
+      return nullptr;
+  }
+  return ReturnFn;
+}
+
+MCSection *HexagonTargetObjectFile::selectSectionForLookupTable(
+    const GlobalObject *GO, const TargetMachine &TM, const Function *Fn) const {
+
+  SectionKind Kind = SectionKind::getText();
+  // If the function has explicit section, place the lookup table in this
+  // explicit section.
+  if (Fn->hasSection())
+    return getExplicitSectionGlobal(Fn, Kind, TM);
+
+  const auto *FuncObj = dyn_cast<GlobalObject>(Fn);
+  return SelectSectionForGlobal(FuncObj, Kind, TM);
+}