1 files changed, 20 insertions, 0 deletions
diff --git a/llvm/lib/Target/X86/X86InstrCompiler.td b/llvm/lib/Target/X86/X86InstrCompiler.td
index 829ea279201..9b39bdc00b5 100644
--- a/llvm/lib/Target/X86/X86InstrCompiler.td
+++ b/llvm/lib/Target/X86/X86InstrCompiler.td
@@ -106,6 +106,26 @@ let Defs = [EAX, ESP, EFLAGS], Uses = [ESP] in
   def WIN_ALLOCA : I<0, Pseudo, (outs), (ins),
                      "# dynamic stack allocation",
                      [(X86WinAlloca)]>;
+
+// When using segmented stacks these are lowered into instructions which first
+// check if the current stacklet has enough free memory. If it does, memory is
+// allocated by bumping the stack pointer. Otherwise memory is allocated from 
+// the heap.
+
+let Defs = [EAX, ESP, EFLAGS], Uses = [ESP, EAX] in
+def SEG_ALLOCA_32 : I<0, Pseudo, (outs GR32:$dst), (ins GR32:$size),
+                      "# variable sized alloca for segmented stacks",
+                      [(set GR32:$dst,
+                         (X86SegAlloca GR32:$size))]>,
+                    Requires<[In32BitMode]>;
+
+let Defs = [RAX, RSP, EFLAGS], Uses = [RSP, RAX] in
+def SEG_ALLOCA_64 : I<0, Pseudo, (outs GR64:$dst), (ins GR64:$size),
+                      "# variable sized alloca for segmented stacks",
+                      [(set GR64:$dst,
+                         (X86SegAlloca GR64:$size))]>,
+                    Requires<[In64BitMode]>;
+
 }