Adds a SelectionDAG node X86SegAlloca which will be custom lowered
from DYNAMIC_STACKALLOC.
Two new pseudo instructions (SEG_ALLOCA_32 and SEG_ALLOCA_64) which
will match X86SegAlloca (based on word size) are also added. They
will be custom emitted to inject the actual stack handling code.
Patch by Sanjoy Das.
llvm-svn: 138814
diff --git a/llvm/lib/Target/X86/X86InstrCompiler.td b/llvm/lib/Target/X86/X86InstrCompiler.td
index 829ea27..9b39bdc 100644
--- a/llvm/lib/Target/X86/X86InstrCompiler.td
+++ b/llvm/lib/Target/X86/X86InstrCompiler.td
@@ -106,6 +106,26 @@
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]>;
+
}