[PowerPC] Don't spill the frame pointer twice
When a function contains something, such as inline asm, which explicitly
clobbers the register used as the frame pointer, don't spill it twice. If we
need a frame pointer, it will be saved/restored in the prologue/epilogue code.
Explicitly spilling it again will reuse the same spill slot used by the
prologue/epilogue code, thus clobbering the saved value. The same applies
to the base-pointer or PIC-base register.
Partially fixes PR26856. Thanks to Ulrich for his analysis and the small
inline-asm reproducer.
llvm-svn: 280188
diff --git a/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp b/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
index 1d8aaac..c59c619 100644
--- a/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
@@ -1419,6 +1419,17 @@
FI->setPICBasePointerSaveIndex(PBPSI);
}
+ // Make sure we don't explicitly spill r31, because, for example, we have
+ // some inline asm which explicity clobbers it, when we otherwise have a
+ // frame pointer and are using r31's spill slot for the prologue/epilogue
+ // code. Same goes for the base pointer and the PIC base register.
+ if (needsFP(MF))
+ SavedRegs.reset(isPPC64 ? PPC::X31 : PPC::R31);
+ if (RegInfo->hasBasePointer(MF))
+ SavedRegs.reset(RegInfo->getBaseRegister(MF));
+ if (FI->usesPICBase())
+ SavedRegs.reset(PPC::R30);
+
// Reserve stack space to move the linkage area to in case of a tail call.
int TCSPDelta = 0;
if (MF.getTarget().Options.GuaranteedTailCallOpt &&