[llvm] r195491 - Teach ISel not to optimize 'optnone' functions (revised).
Paul Robinson
paul_robinson at playstation.sony.com
Fri Nov 22 11:11:24 PST 2013
Author: probinson
Date: Fri Nov 22 13:11:24 2013
New Revision: 195491
URL: http://llvm.org/viewvc/llvm-project?rev=195491&view=rev
Log:
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.
Added:
llvm/trunk/test/CodeGen/X86/isel-optnone.ll
Modified:
llvm/trunk/include/llvm/MC/MCCodeGenInfo.h
llvm/trunk/include/llvm/Target/TargetMachine.h
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
llvm/trunk/lib/Target/TargetMachine.cpp
Modified: llvm/trunk/include/llvm/MC/MCCodeGenInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCCodeGenInfo.h?rev=195491&r1=195490&r2=195491&view=diff
==============================================================================
--- llvm/trunk/include/llvm/MC/MCCodeGenInfo.h (original)
+++ llvm/trunk/include/llvm/MC/MCCodeGenInfo.h Fri Nov 22 13:11:24 2013
@@ -42,6 +42,9 @@ namespace llvm {
CodeModel::Model getCodeModel() const { return CMModel; }
CodeGenOpt::Level getOptLevel() const { return OptLevel; }
+
+ // Allow overriding OptLevel on a per-function basis.
+ void setOptLevel(CodeGenOpt::Level Level) { OptLevel = Level; }
};
} // namespace llvm
Modified: llvm/trunk/include/llvm/Target/TargetMachine.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetMachine.h?rev=195491&r1=195490&r2=195491&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetMachine.h (original)
+++ llvm/trunk/include/llvm/Target/TargetMachine.h Fri Nov 22 13:11:24 2013
@@ -75,7 +75,8 @@ protected: // Can only create subclasses
std::string TargetFS;
/// CodeGenInfo - Low level target information such as relocation model.
- const MCCodeGenInfo *CodeGenInfo;
+ /// Non-const to allow resetting optimization level per-function.
+ MCCodeGenInfo *CodeGenInfo;
/// AsmInfo - Contains target specific asm information.
///
@@ -213,6 +214,9 @@ public:
/// Default, or Aggressive.
CodeGenOpt::Level getOptLevel() const;
+ /// \brief Overrides the optimization level.
+ void setOptLevel(CodeGenOpt::Level Level) const;
+
void setFastISel(bool Enable) { Options.EnableFastISel = Enable; }
bool shouldPrintMachineCode() const { return Options.PrintMachineCode; }
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp?rev=195491&r1=195490&r2=195491&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp Fri Nov 22 13:11:24 2013
@@ -223,6 +223,44 @@ defaultListDAGScheduler("default", "Best
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 @@ bool SelectionDAGISel::runOnMachineFunct
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);
Modified: llvm/trunk/lib/Target/TargetMachine.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/TargetMachine.cpp?rev=195491&r1=195490&r2=195491&view=diff
==============================================================================
--- llvm/trunk/lib/Target/TargetMachine.cpp (original)
+++ llvm/trunk/lib/Target/TargetMachine.cpp Fri Nov 22 13:11:24 2013
@@ -164,6 +164,11 @@ CodeGenOpt::Level TargetMachine::getOptL
return CodeGenInfo->getOptLevel();
}
+void TargetMachine::setOptLevel(CodeGenOpt::Level Level) const {
+ if (CodeGenInfo)
+ CodeGenInfo->setOptLevel(Level);
+}
+
bool TargetMachine::getAsmVerbosityDefault() {
return AsmVerbosityDefault;
}
Added: llvm/trunk/test/CodeGen/X86/isel-optnone.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/isel-optnone.ll?rev=195491&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/isel-optnone.ll (added)
+++ llvm/trunk/test/CodeGen/X86/isel-optnone.ll Fri Nov 22 13:11:24 2013
@@ -0,0 +1,42 @@
+; RUN: llc -O2 -march=x86 < %s | FileCheck %s
+
+define i32* @fooOptnone(i32* %p, i32* %q, i32** %z) #0 {
+entry:
+ %r = load i32* %p
+ %s = load i32* %q
+ %y = load i32** %z
+
+ %t0 = add i32 %r, %s
+ %t1 = add i32 %t0, 1
+ %t2 = getelementptr i32* %y, i32 1
+ %t3 = getelementptr i32* %t2, i32 %t1
+
+ ret i32* %t3
+
+; 'optnone' should use fast-isel which will not produce 'lea'.
+; CHECK-LABEL: fooOptnone:
+; CHECK-NOT: lea
+; CHECK: ret
+}
+
+define i32* @fooNormal(i32* %p, i32* %q, i32** %z) #1 {
+entry:
+ %r = load i32* %p
+ %s = load i32* %q
+ %y = load i32** %z
+
+ %t0 = add i32 %r, %s
+ %t1 = add i32 %t0, 1
+ %t2 = getelementptr i32* %y, i32 1
+ %t3 = getelementptr i32* %t2, i32 %t1
+
+ ret i32* %t3
+
+; Normal ISel will produce 'lea'.
+; CHECK-LABEL: fooNormal:
+; CHECK: lea
+; CHECK: ret
+}
+
+attributes #0 = { nounwind optnone noinline }
+attributes #1 = { nounwind }
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