Merging r195491:
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r195491 | probinson | 2013-11-22 11:11:24 -0800 (Fri, 22 Nov 2013) | 11 lines
Teach ISel not to optimize 'optnone' functions (revised).
Improvements over r195317:
- Set/restore EnableFastISel flag instead of just running FastISel within
SelectAllBasicBlocks; the flag is checked in various places, and
FastISel won't run properly if those places don't do the right thing.
- Test looks for normal ISel versus FastISel behavior, and not
something more subtle that doesn't work everywhere.
Based on work by Andrea Di Biagio.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_34@195604 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 15f2ee2..50d6402 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -223,6 +223,44 @@
namespace llvm {
//===--------------------------------------------------------------------===//
+ /// \brief This class is used by SelectionDAGISel to temporarily override
+ /// the optimization level on a per-function basis.
+ class OptLevelChanger {
+ SelectionDAGISel &IS;
+ CodeGenOpt::Level SavedOptLevel;
+ bool SavedFastISel;
+
+ public:
+ OptLevelChanger(SelectionDAGISel &ISel,
+ CodeGenOpt::Level NewOptLevel) : IS(ISel) {
+ SavedOptLevel = IS.OptLevel;
+ if (NewOptLevel == SavedOptLevel)
+ return;
+ IS.OptLevel = NewOptLevel;
+ IS.TM.setOptLevel(NewOptLevel);
+ SavedFastISel = IS.TM.Options.EnableFastISel;
+ if (NewOptLevel == CodeGenOpt::None)
+ IS.TM.setFastISel(true);
+ DEBUG(dbgs() << "\nChanging optimization level for Function "
+ << IS.MF->getFunction()->getName() << "\n");
+ DEBUG(dbgs() << "\tBefore: -O" << SavedOptLevel
+ << " ; After: -O" << NewOptLevel << "\n");
+ }
+
+ ~OptLevelChanger() {
+ if (IS.OptLevel == SavedOptLevel)
+ return;
+ DEBUG(dbgs() << "\nRestoring optimization level for Function "
+ << IS.MF->getFunction()->getName() << "\n");
+ DEBUG(dbgs() << "\tBefore: -O" << IS.OptLevel
+ << " ; After: -O" << SavedOptLevel << "\n");
+ IS.OptLevel = SavedOptLevel;
+ IS.TM.setOptLevel(SavedOptLevel);
+ IS.TM.setFastISel(SavedFastISel);
+ }
+ };
+
+ //===--------------------------------------------------------------------===//
/// createDefaultScheduler - This creates an instruction scheduler appropriate
/// for the target.
ScheduleDAGSDNodes* createDefaultScheduler(SelectionDAGISel *IS,
@@ -370,6 +408,12 @@
ST.resetSubtargetFeatures(MF);
TM.resetTargetOptions(MF);
+ // Reset OptLevel to None for optnone functions.
+ CodeGenOpt::Level NewOptLevel = OptLevel;
+ if (Fn.hasFnAttribute(Attribute::OptimizeNone))
+ NewOptLevel = CodeGenOpt::None;
+ OptLevelChanger OLC(*this, NewOptLevel);
+
DEBUG(dbgs() << "\n\n\n=== " << Fn.getName() << "\n");
SplitCriticalSideEffectEdges(const_cast<Function&>(Fn), this);