[llvm-commits] [llvm] r157133 - /llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp

[Hal Finkel]

Author: hfinkel
Date: Sat May 19 16:52:55 2012
New Revision: 157133

URL: http://llvm.org/viewvc/llvm-project?rev=157133&view=rev
Log:
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.

Modified:
    llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp

Modified: llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp?rev=157133&r1=157132&r2=157133&view=diff
==============================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp (original)
+++ llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp Sat May 19 16:52:55 2012
@@ -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)