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, 8 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/ARMFrameLowering.cpp b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
index 4eafd82af4c..a52e49780e2 100644
--- a/llvm/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
@@ -43,6 +43,14 @@ ARMFrameLowering::ARMFrameLowering(const ARMSubtarget &sti)
     : TargetFrameLowering(StackGrowsDown, sti.getStackAlignment(), 0, 4),
       STI(sti) {}
 
+bool ARMFrameLowering::noFramePointerElim(const MachineFunction &MF) const {
+  // iOS always has a FP for backtracking, force other targets to keep their FP
+  // when doing FastISel. The emitted code is currently superior, and in cases
+  // like test-suite's lencod FastISel isn't quite correct when FP is eliminated.
+  return TargetFrameLowering::noFramePointerElim(MF) ||
+         MF.getSubtarget<ARMSubtarget>().useFastISel();
+}
+
 /// hasFP - Return true if the specified function should have a dedicated frame
 /// pointer register.  This is true if the function has variable sized allocas
 /// or if frame pointer elimination is disabled.