Fix PR6696 and PR6663
When a frame pointer is not otherwise required, and dynamic stack alignment
is necessary solely due to the spilling of a register with larger alignment
requirements than the default stack alignment, the frame pointer can be both
used as a general purpose register and a frame pointer. That goes poorly, for
obvious reasons. This patch brings back a bit of old logic for identifying
the use of such registers and conservatively reserves the frame pointer
during register allocation in such cases.
For now, implement for X86 only since it's 32-bit linux which is hitting this,
and we want a targeted fix for 2.7. As a follow-on, this will be expanded
to handle other targets, as theoretically the problem could arise elsewhere
as well.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100559 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86MachineFunctionInfo.h b/lib/Target/X86/X86MachineFunctionInfo.h
index 4b2529b..a916c63 100644
--- a/lib/Target/X86/X86MachineFunctionInfo.h
+++ b/lib/Target/X86/X86MachineFunctionInfo.h
@@ -52,6 +52,10 @@
/// relocation models.
unsigned GlobalBaseReg;
+ /// ReserveFP - whether the function should reserve the frame pointer
+ /// when allocating, even if there may not actually be a frame pointer used.
+ bool ReserveFP;
+
public:
X86MachineFunctionInfo() : ForceFramePointer(false),
CalleeSavedFrameSize(0),
@@ -68,7 +72,8 @@
ReturnAddrIndex(0),
TailCallReturnAddrDelta(0),
SRetReturnReg(0),
- GlobalBaseReg(0) {}
+ GlobalBaseReg(0),
+ ReserveFP(false) {}
bool getForceFramePointer() const { return ForceFramePointer;}
void setForceFramePointer(bool forceFP) { ForceFramePointer = forceFP; }
@@ -90,6 +95,9 @@
unsigned getGlobalBaseReg() const { return GlobalBaseReg; }
void setGlobalBaseReg(unsigned Reg) { GlobalBaseReg = Reg; }
+
+ bool getReserveFP() const { return ReserveFP; }
+ void setReserveFP(bool reserveFP) { ReserveFP = reserveFP; }
};
} // End llvm namespace