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[AVR] Fix incorrect selection of post indexed addresses #145040

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[AVR] Fix incorrect selection of post indexed addresses #145040

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938ee7a
[AVR] Temp fix in getPostIndexedAddressParts()
tomtor Jun 17, 2025
7dc79da
fix comment length
tomtor Jun 21, 2025
d46bebc
Try Patryk27 fix
tomtor Jun 21, 2025
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14 changes: 14 additions & 0 deletions llvm/lib/Target/AVR/AVRISelLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1114,8 +1114,22 @@ bool AVRTargetLowering::getPostIndexedAddressParts(SDNode *N, SDNode *Op,
if (AVR::isProgramMemoryAccess(LD))
return false;

SDValue Ptr;
if (LoadSDNode *LD = dyn_cast<LoadSDNode>(N)) {
Ptr = LD->getBasePtr();
} else if (StoreSDNode *ST = dyn_cast<StoreSDNode>(N)) {
Ptr = ST->getBasePtr();
} else
return false;

Base = Op->getOperand(0);
Offset = DAG.getConstant(RHSC, DL, MVT::i8);

// Post-indexing updates the base, so it's not a valid transform
// if that's not the same as the load's pointer.
if (Ptr != Base)
return false;

AM = ISD::POST_INC;

return true;
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23 changes: 23 additions & 0 deletions llvm/test/CodeGen/AVR/issue-145040.ll
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@@ -0,0 +1,23 @@
; RUN: llc < %s -O=2 -mtriple=avr-none --mcpu=avr128db28 -verify-machineinstrs | FileCheck %s

declare dso_local void @nil(i16 noundef) local_unnamed_addr addrspace(1) #1
!3 = !{!4, !4, i64 0}
!4 = !{!"omnipotent char", !5, i64 0}
!5 = !{!"Simple C/C++ TBAA"}

define void @complex_sbi() {
; CHECK: sbi 1, 7
entry:
br label %while.cond
while.cond: ; preds = %while.cond, %entry
%s.0 = phi i16 [ 0, %entry ], [ %inc, %while.cond ]
%inc = add nuw nsw i16 %s.0, 1
%0 = load volatile i8, ptr inttoptr (i16 1 to ptr), align 1, !tbaa !3
%or = or i8 %0, -128
store volatile i8 %or, ptr inttoptr (i16 1 to ptr), align 1, !tbaa !3
%and = and i16 %inc, 15
%add = add nuw nsw i16 %and, 1
tail call addrspace(1) void @nil(i16 noundef %add) #2
br label %while.cond
}