ARM: fix bug in -Oz stack adjustment folding

Previously, we clobbered callee-saved registers when folding an "add
sp, #N" into a "pop {rD, ...}" instruction. This change checks whether
a register we're going to add to the "pop" could actually be live
outside the function before doing so and should fix the issue.

This should fix PR18081.

llvm-svn: 196046

1 files changed, 0 insertions, 7 deletions

diff --git a/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp b/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp
index d921c82cfb0..cfb33f5b821 100644
--- a/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp
+++ b/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp
@@ -215,13 +215,6 @@ void Thumb1FrameLowering::emitPrologue(MachineFunction &MF) const {
     AFI->setShouldRestoreSPFromFP(true);
 }
 
-static bool isCalleeSavedRegister(unsigned Reg, const uint16_t *CSRegs) {
-  for (unsigned i = 0; CSRegs[i]; ++i)
-    if (Reg == CSRegs[i])
-      return true;
-  return false;
-}
-
 static bool isCSRestore(MachineInstr *MI, const uint16_t *CSRegs) {
   if (MI->getOpcode() == ARM::tLDRspi &&
       MI->getOperand(1).isFI() &&