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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138814 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 2041c3c..a885699 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -10636,6 +10636,7 @@
case X86ISD::VAARG_64: return "X86ISD::VAARG_64";
case X86ISD::WIN_ALLOCA: return "X86ISD::WIN_ALLOCA";
case X86ISD::MEMBARRIER: return "X86ISD::MEMBARRIER";
+ case X86ISD::SEG_ALLOCA: return "X86ISD::SEG_ALLOCA";
}
}
diff --git a/lib/Target/X86/X86ISelLowering.h b/lib/Target/X86/X86ISelLowering.h
index 6419879..9a9093c 100644
--- a/lib/Target/X86/X86ISelLowering.h
+++ b/lib/Target/X86/X86ISelLowering.h
@@ -286,6 +286,11 @@
// WIN_ALLOCA - Windows's _chkstk call to do stack probing.
WIN_ALLOCA,
+ // SEG_ALLOCA - For allocating variable amounts of stack space when using
+ // segmented stacks. Check if the current stacklet has enough space, and
+ // defects to heap allocation if not.
+ SEG_ALLOCA,
+
// Memory barrier
MEMBARRIER,
MFENCE,
diff --git a/lib/Target/X86/X86InstrCompiler.td b/lib/Target/X86/X86InstrCompiler.td
index 829ea27..9b39bdc 100644
--- a/lib/Target/X86/X86InstrCompiler.td
+++ b/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]>;
+
}
diff --git a/lib/Target/X86/X86InstrInfo.td b/lib/Target/X86/X86InstrInfo.td
index a09edd4..903d1b2 100644
--- a/lib/Target/X86/X86InstrInfo.td
+++ b/lib/Target/X86/X86InstrInfo.td
@@ -97,6 +97,8 @@
def SDT_X86TLSCALL : SDTypeProfile<0, 1, [SDTCisInt<0>]>;
+def SDT_X86SEG_ALLOCA : SDTypeProfile<1, 1, [SDTCisVT<0, iPTR>, SDTCisVT<1, iPTR>]>;
+
def SDT_X86EHRET : SDTypeProfile<0, 1, [SDTCisInt<0>]>;
def SDT_X86TCRET : SDTypeProfile<0, 2, [SDTCisPtrTy<0>, SDTCisVT<1, i32>]>;
@@ -228,6 +230,9 @@
def X86WinAlloca : SDNode<"X86ISD::WIN_ALLOCA", SDTX86Void,
[SDNPHasChain, SDNPInGlue, SDNPOutGlue]>;
+def X86SegAlloca : SDNode<"X86ISD::SEG_ALLOCA", SDT_X86SEG_ALLOCA,
+ [SDNPHasChain]>;
+
def X86TLSCall : SDNode<"X86ISD::TLSCALL", SDT_X86TLSCALL,
[SDNPHasChain, SDNPOptInGlue, SDNPOutGlue]>;
