commit 62c1a1e7c7fc13b6763f999d100d91cff69afd93
author Geoff Berry <gberry@codeaurora.org> Wed Mar 02 17:58:31 2016 +0000
committer Geoff Berry <gberry@codeaurora.org> Wed Mar 02 17:58:31 2016 +0000
tree 12be1b475faac8a006f71dd0730a605fa48e6bf9
parent 7d942d73b868a9ce7e202096778803d57f3ec73c

[AArch64] Enable non-leaf frame pointer elimination.

Summary:
This change enables frame pointer elimination in non-leaf functions.
The -fomit-frame-pointer option still needs to be used when compiling
via clang (or an equivalent method of not setting the
'no-frame-pointer-elim*' function attributes if generating llvm IR via
some other method) to take advantage of this optimization.

This change should be NFC when compiling via clang without
-fomit-frame-pointer.

Reviewers: t.p.northover

Subscribers: aemerson, rengolin, tberghammer, qcolombet, llvm-commits, danalbert, mcrosier, srhines

Differential Revision: http://reviews.llvm.org/D17730

llvm-svn: 262495

llvm/lib/Target/AArch64/AArch64FrameLowering.cpp

diff --git a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
index 5b6385e..0ed522b 100644
--- a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -127,9 +127,6 @@
   const AArch64FunctionInfo *AFI = MF.getInfo<AArch64FunctionInfo>();
   unsigned NumBytes = AFI->getLocalStackSize();
 
-  // Note: currently hasFP() is always true for hasCalls(), but that's an
-  // implementation detail of the current code, not a strict requirement,
-  // so stay safe here and check both.
   return !(MFI->hasCalls() || hasFP(MF) || NumBytes > 128);
 }
 
@@ -138,9 +135,12 @@
 bool AArch64FrameLowering::hasFP(const MachineFunction &MF) const {
   const MachineFrameInfo *MFI = MF.getFrameInfo();
   const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
-  return (MFI->hasCalls() || MFI->hasVarSizedObjects() ||
-          MFI->isFrameAddressTaken() || MFI->hasStackMap() ||
-          MFI->hasPatchPoint() || RegInfo->needsStackRealignment(MF));
+  // Retain behavior of always omitting the FP for leaf functions when possible.
+  return (MFI->hasCalls() &&
+          MF.getTarget().Options.DisableFramePointerElim(MF)) ||
+         MFI->hasVarSizedObjects() || MFI->isFrameAddressTaken() ||
+         MFI->hasStackMap() || MFI->hasPatchPoint() ||
+         RegInfo->needsStackRealignment(MF);
 }
 
 /// hasReservedCallFrame - Under normal circumstances, when a frame pointer is