Stop resetting NoFramePointerElim in TargetMachine::resetTargetOptions.

This is part of the work to remove TargetMachine::resetTargetOptions.

In this patch, instead of updating global variable NoFramePointerElim in
resetTargetOptions, its use in DisableFramePointerElim is replaced with a call
to TargetFrameLowering::noFramePointerElim. This function determines on a
per-function basis if frame pointer elimination should be disabled.

There is no change in functionality except that cl:opt option "disable-fp-elim"
can now override function attribute "no-frame-pointer-elim". 

llvm-svn: 238080

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp b/llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp
index e3f01912b87..56383247ead 100644
--- a/llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp
+++ b/llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp
@@ -14,6 +14,7 @@
 #include "llvm/Target/TargetFrameLowering.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/IR/Function.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetSubtargetInfo.h"
 #include <cstdlib>
@@ -22,6 +23,12 @@ using namespace llvm;
 TargetFrameLowering::~TargetFrameLowering() {
 }
 
+/// The default implementation just looks at attribute "no-frame-pointer-elim".
+bool TargetFrameLowering::noFramePointerElim(const MachineFunction &MF) const {
+  auto Attr = MF.getFunction()->getFnAttribute("no-frame-pointer-elim");
+  return Attr.getValueAsString() == "true";
+}
+
 /// getFrameIndexOffset - Returns the displacement from the frame register to
 /// the stack frame of the specified index. This is the default implementation
 /// which is overridden for some targets.