[PATCH] D69034: [Alignment][NFC] Use Align for TFI.getStackAlignment() in X86ISelLowering

[Clement Courbet via Phabricator via llvm-commits]

courbet requested changes to this revision.
courbet added inline comments.
This revision now requires changes to proceed.


================
Comment at: llvm/lib/Target/X86/X86ISelLowering.cpp:4186
 unsigned
-X86TargetLowering::GetAlignedArgumentStackSize(unsigned StackSize,
-                                               SelectionDAG& DAG) const {
-  const X86RegisterInfo *RegInfo = Subtarget.getRegisterInfo();
-  const TargetFrameLowering &TFI = *Subtarget.getFrameLowering();
-  unsigned StackAlignment = TFI.getStackAlignment();
-  uint64_t AlignMask = StackAlignment - 1;
-  int64_t Offset = StackSize;
-  unsigned SlotSize = RegInfo->getSlotSize();
-  if ( (Offset & AlignMask) <= (StackAlignment - SlotSize) ) {
-    // Number smaller than 12 so just add the difference.
-    Offset += ((StackAlignment - SlotSize) - (Offset & AlignMask));
-  } else {
-    // Mask out lower bits, add stackalignment once plus the 12 bytes.
-    Offset = ((~AlignMask) & Offset) + StackAlignment +
-      (StackAlignment-SlotSize);
-  }
-  return Offset;
+X86TargetLowering::GetAlignedArgumentStackSize(const unsigned StackSize,
+                                               SelectionDAG &DAG) const {
----------------
This is not the same as the previous code for all values: https://godbolt.org/z/QTxj9U
Could you at least add an assert if you don;t intend to cover the same range of inputs ?


================
Comment at: llvm/lib/Target/X86/X86ISelLowering.cpp:22218
       SP = DAG.getNode(ISD::AND, dl, VT, SP.getValue(0),
-                       DAG.getConstant(-(uint64_t)Align, dl, VT));
+                       DAG.getConstant(~(Alignment->value() - 1ULL), dl, VT));
       Chain = DAG.getCopyToReg(Chain, dl, SPReg, SP);
----------------
Let's refactor this in `Align` (in a separate patch).


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D69034/new/

https://reviews.llvm.org/D69034