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[X86] Restore X86 base pointer after call to llvm.eh.sjlj.setjmp

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- This patch fixes the bug described in
  http://lists.cs.uiuc.edu/pipermail/llvmdev/2013-May/062343.html

The fix allocates an extra slot just below the GPRs and stores the base pointer
there. This is done only for functions containing llvm.eh.sjlj.setjmp that also
need a base pointer. Because code containing llvm.eh.sjlj.setjmp saves all of
the callee-save GPRs in the prologue, the offset to the extra slot can be
computed before prologue generation runs.

Impact at run-time on affected functions is::

  - One extra store in the prologue, The store saves the base pointer.
  - One extra load after a llvm.eh.sjlj.setjmp. The load restores the base pointer.

Because the extra slot is just above a gap between frame-pointer-relative and
base-pointer-relative chunks of memory, there is no impact on other offset
calculations other than ensuring there is room for the extra slot.

http://reviews.llvm.org/D6388

Patch by Arch Robison <arch.robison@intel.com>



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223329 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Liao
2014-12-04 00:56:38 +00:00
parent ec086bf087
commit fd0832ea89
5 changed files with 94 additions and 0 deletions
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19
lib/Target/X86/X86MachineFunctionInfo.cpp
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@@ -8,7 +8,26 @@
//===----------------------------------------------------------------------===//
#include "X86MachineFunctionInfo.h"
#include "X86RegisterInfo.h"
#include "llvm/Target/TargetSubtargetInfo.h"
using namespace llvm;
void X86MachineFunctionInfo::anchor() { }
void X86MachineFunctionInfo::setRestoreBasePointer(const MachineFunction *MF) {
if (!RestoreBasePointerOffset) {
const X86RegisterInfo *RegInfo = static_cast<const X86RegisterInfo *>(
MF->getSubtarget().getRegisterInfo());
unsigned SlotSize = RegInfo->getSlotSize();
for (const MCPhysReg *CSR =
RegInfo->X86RegisterInfo::getCalleeSavedRegs(MF);
unsigned Reg = *CSR;
++CSR)
{
if (X86::GR64RegClass.contains(Reg) || X86::GR32RegClass.contains(Reg))
RestoreBasePointerOffset -= SlotSize;
}
}
}