ARM: Compute MaxCallFrame size early

This exposes a method in MachineFrameInfo that calculates
MaxCallFrameSize and calls it after instruction selection in the ARM
target.

This avoids
ARMBaseRegisterInfo::canRealignStack()/ARMFrameLowering::hasReservedCallFrame()
giving different answers in early/late phases of codegen.

The testcase shows a particular nasty example result of that where we
would fail to properly align an alloca.

Differential Revision: https://reviews.llvm.org/D32622

llvm-svn: 302303

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/include/llvm/CodeGen/MachineFrameInfo.h b/llvm/include/llvm/CodeGen/MachineFrameInfo.h
index 61be9f775c9..689f3cd9fd1 100644
--- a/llvm/include/llvm/CodeGen/MachineFrameInfo.h
+++ b/llvm/include/llvm/CodeGen/MachineFrameInfo.h
@@ -520,6 +520,14 @@ public:
   bool hasTailCall() const { return HasTailCall; }
   void setHasTailCall() { HasTailCall = true; }
 
+  /// Computes the maximum size of a callframe and the AdjustsStack property.
+  /// This only works for targets defining
+  /// TargetInstrInfo::getCallFrameSetupOpcode(), getCallFrameDestroyOpcode(),
+  /// and getFrameSize().
+  /// This is usually computed by the prologue epilogue inserter but some
+  /// targets may call this to compute it earlier.
+  void computeMaxCallFrameSize(const MachineFunction &MF);
+
   /// Return the maximum size of a call frame that must be
   /// allocated for an outgoing function call.  This is only available if
   /// CallFrameSetup/Destroy pseudo instructions are used by the target, and