Emit segmented-stack specific code into function prologues for

X86. Modify the pass added in the previous patch to call this new
code.

This new prologues generated will call a libgcc routine (__morestack)
to allocate more stack space from the heap when required

Patch by Sanjoy Das.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138812 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp
index 7e5d804f91..ec5fe25704 100644
--- a/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/lib/CodeGen/PrologEpilogInserter.cpp
@@ -29,6 +29,7 @@
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/RegisterScavenging.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetFrameLowering.h"
 #include "llvm/Target/TargetInstrInfo.h"
@@ -699,6 +700,13 @@ void PEI::insertPrologEpilogCode(MachineFunction &Fn) {
     if (!I->empty() && I->back().getDesc().isReturn())
       TFI.emitEpilogue(Fn, *I);
   }
+
+  // Emit additional code that is required support segmented stacks, if we've
+  // been asked for it.  This, when linked with a runtime with support for
+  // segmented stacks (libgcc is one), will result allocating stack space in
+  // small chunks instead of one large contiguous block.
+  if (EnableSegmentedStacks)
+    TFI.adjustForSegmentedStacks(Fn);
 }
 
 /// replaceFrameIndices - Replace all MO_FrameIndex operands with physical