Reset some of the target options which affect code generation.

This doesn't reset all of the target options within the TargetOptions
object. This is because some of those are ABI-specific and must be determined if
it's okay to change those on the fly.

llvm-svn: 176986

3 files changed, 31 insertions, 1 deletions

diff --git a/llvm/include/llvm/Target/TargetMachine.h b/llvm/include/llvm/Target/TargetMachine.h
index 35cf20a7028..66f3a3c71b6 100644
--- a/llvm/include/llvm/Target/TargetMachine.h
+++ b/llvm/include/llvm/Target/TargetMachine.h
@@ -95,7 +95,10 @@ public:
   /// a reference to that target's TargetSubtargetInfo-derived member variable.
   virtual const TargetSubtargetInfo *getSubtargetImpl() const { return 0; }
 
-  TargetOptions Options;
+  mutable TargetOptions Options;
+
+  /// \brief Reset the target options based on the function's attributes.
+  void resetTargetOptions(const MachineFunction *MF) const;
 
   // Interfaces to the major aspects of target machine information:
   // -- Instruction opcode and operand information
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 39a1f8a3d0d..c3b6276a8dc 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -362,6 +362,7 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
   TargetSubtargetInfo &ST =
     const_cast<TargetSubtargetInfo&>(TM.getSubtarget<TargetSubtargetInfo>());
   ST.resetSubtargetFeatures(MF);
+  TM.resetTargetOptions(MF);
 
   DEBUG(dbgs() << "\n\n\n=== " << Fn.getName() << "\n");
 
diff --git a/llvm/lib/Target/TargetMachine.cpp b/llvm/lib/Target/TargetMachine.cpp
index 7d8b49cdf23..e7282519d59 100644
--- a/llvm/lib/Target/TargetMachine.cpp
+++ b/llvm/lib/Target/TargetMachine.cpp
@@ -12,6 +12,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalAlias.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/GlobalVariable.h"
@@ -61,6 +63,30 @@ TargetMachine::~TargetMachine() {
   delete AsmInfo;
 }
 
+/// \brief Reset the target options based on the function's attributes.
+void TargetMachine::resetTargetOptions(const MachineFunction *MF) const {
+  const Function *F = MF->getFunction();
+  TargetOptions &TO = MF->getTarget().Options;
+  
+#define RESET_OPTION(X, Y)                                              \
+  do {                                                                  \
+    if (F->hasFnAttribute(Y))                                           \
+      TO.X =                                                            \
+        (F->getAttributes().                                            \
+           getAttribute(AttributeSet::FunctionIndex,                    \
+                        Y).getValueAsString() == "true");               \
+  } while (0)
+
+  RESET_OPTION(NoFramePointerElim, "no-frame-pointer-elim");
+  RESET_OPTION(NoFramePointerElimNonLeaf, "no-frame-pointer-elim-non-leaf");
+  RESET_OPTION(LessPreciseFPMADOption, "less-precise-fpmad");
+  RESET_OPTION(UnsafeFPMath, "unsafe-fp-math");
+  RESET_OPTION(NoInfsFPMath, "no-infs-fp-math");
+  RESET_OPTION(NoNaNsFPMath, "no-nans-fp-math");
+  RESET_OPTION(UseSoftFloat, "use-soft-float");
+  RESET_OPTION(DisableTailCalls, "disable-tail-calls");
+}
+
 /// getRelocationModel - Returns the code generation relocation model. The
 /// choices are static, PIC, and dynamic-no-pic, and target default.
 Reloc::Model TargetMachine::getRelocationModel() const {