[PATCH] D80644: DAG: Fix expansion of DYNAMIC_STACKALLOC for StackGrowsUp targets

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: scott.linder, rampitec, craig.topper, RKSimon, efriedma.
Herald added subscribers: hiraditya, tpr, wdng.
Herald added a project: LLVM.

Tests will be included with AMDGPU patch to start using this
expansion.


https://reviews.llvm.org/D80644

Files:
  llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp


Index: llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -1600,9 +1600,13 @@
   SDValue SP = DAG.getCopyFromReg(Chain, dl, SPReg, VT);
   Chain = SP.getValue(1);
   unsigned Align = cast<ConstantSDNode>(Tmp3)->getZExtValue();
-  unsigned StackAlign =
-      DAG.getSubtarget().getFrameLowering()->getStackAlignment();
-  Tmp1 = DAG.getNode(ISD::SUB, dl, VT, SP, Size);       // Value
+  const TargetFrameLowering *TFL = DAG.getSubtarget().getFrameLowering();
+  unsigned Opc =
+    TFL->getStackGrowthDirection() == TargetFrameLowering::StackGrowsUp ?
+    ISD::ADD : ISD::SUB;
+
+  unsigned StackAlign = TFL->getStackAlignment();
+  Tmp1 = DAG.getNode(Opc, dl, VT, SP, Size);       // Value
   if (Align > StackAlign)
     Tmp1 = DAG.getNode(ISD::AND, dl, VT, Tmp1,
                        DAG.getConstant(-(uint64_t)Align, dl, VT));


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