Add a FIXME about access to negative stack-pointer offsets on PPC32.
The current code will generate a prologue which starts with something like:
mflr 0
stw 31, -4(1)
stw 0, 4(1)
stwu 1, -16(1)
But under the PPC32 SVR4 ABI, access to negative offsets from R1 is not allowed.
This was pointed out by Peter Bergner.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157133 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCFrameLowering.cpp b/lib/Target/PowerPC/PPCFrameLowering.cpp
index 5950290..be172c2 100644
--- a/lib/Target/PowerPC/PPCFrameLowering.cpp
+++ b/lib/Target/PowerPC/PPCFrameLowering.cpp
@@ -330,6 +330,8 @@
BuildMI(MBB, MBBI, dl, TII.get(PPC::MFLR), PPC::R0);
if (HasFP)
+ // FIXME: On PPC32 SVR4, FPOffset is negative and access to negative
+ // offsets of R1 is not allowed.
BuildMI(MBB, MBBI, dl, TII.get(PPC::STW))
.addReg(PPC::R31)
.addImm(FPOffset)