PEI is now responsible for adding MaxCallFrameSize to frame size and align the stack. Each target can further adjust the frame size if necessary.

llvm-svn: 33460

1 files changed, 16 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
index 616e2ac7efa..915fbc252bf 100644
--- a/llvm/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -386,7 +386,22 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
     }
   }
 
-  // Set the final value of the stack pointer...
+  // Round up the size to a multiple of the alignment, but only if there are
+  // calls or alloca's in the function.  This ensures that any calls to
+  // subroutines have their stack frames suitable aligned.
+  if (FFI->hasCalls() || FFI->hasVarSizedObjects()) {
+    // When we have no frame pointer, we reserve argument space for call sites
+    // in the function immediately on entry to the current function. This
+    // eliminates the need for add/sub sp brackets around call sites.
+    const MRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
+    if (!RegInfo->hasFP(Fn))
+      Offset += FFI->getMaxCallFrameSize();
+
+    unsigned AlignMask = TFI.getStackAlignment() - 1;
+    Offset = (Offset + AlignMask) & ~AlignMask;
+  }
+
+  // Update frame info to pretend that this is part of the stack...
   FFI->setStackSize(Offset+TFI.getOffsetOfLocalArea());
 
   // Remember the required stack alignment in case targets need it to perform