PPC: Support dynamic allocas with large alignment
Support for dynamic stack alignments in the PPC backend has been unfinished, in
part because it depends on dynamic stack realignment (which I only just
recently implemented fully). Now we can also support dynamic allocas with
higher than the default target stack alignment (16 bytes).
In order to round-up the requested size to the maximum requested alignment, we
need an additional register to hold the rounded-up size. We're already using one
scavenged register to hold the previous stack-pointer value (which needs to be
stored with the signal-safe stdux update), and so when we have dynamic allocas
and a large alignment, we allocate two emergency spill slots for the scavenger.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186562 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCFrameLowering.cpp b/lib/Target/PowerPC/PPCFrameLowering.cpp
index d846365..24d3a0b 100644
--- a/lib/Target/PowerPC/PPCFrameLowering.cpp
+++ b/lib/Target/PowerPC/PPCFrameLowering.cpp
@@ -1237,8 +1237,12 @@
RC->getAlignment(),
false));
+ // Might we have over-aligned allocas?
+ bool HasAlVars = MFI->hasVarSizedObjects() &&
+ MFI->getMaxAlignment() > getStackAlignment();
+
// These kinds of spills might need two registers.
- if (spillsCR(MF) || spillsVRSAVE(MF))
+ if (spillsCR(MF) || spillsVRSAVE(MF) || HasAlVars)
RS->addScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
RC->getAlignment(),
false));