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

Commit on 

- 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>

llvm-svn: 223329

1 files changed, 19 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86MachineFunctionInfo.cpp b/llvm/lib/Target/X86/X86MachineFunctionInfo.cpp
index 568dc22..95183959 100644
--- a/llvm/lib/Target/X86/X86MachineFunctionInfo.cpp
+++ b/llvm/lib/Target/X86/X86MachineFunctionInfo.cpp
@@ -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;
+    }
+  }
+}
+