[PATCH] D84746: [SVE][CodeGen] At -O0 fallback to DAG ISel when translating alloca with scalable types

[David Sherwood via Phabricator via llvm-commits]

david-arm created this revision.
david-arm added reviewers: sdesmalen, aemerson, kmclaughlin.
Herald added subscribers: llvm-commits, psnobl, hiraditya, kristof.beyls, tschuett.
Herald added a reviewer: efriedma.
Herald added a project: LLVM.
david-arm requested review of this revision.

When building code at -O0 we weren't falling back to DAG ISel correctly
when encountering alloca instructions with scalable vector types. This
is because the alloca has no operands that are scalable. I've fixed this by
adding a check in AArch64ISelLowering::fallBackToDAGISel for alloca
instructions with scalable types.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D84746

Files:
  llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
  llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll


Index: llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll
===================================================================
--- llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll
+++ llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll
@@ -244,6 +244,14 @@
   ret i8 %res
 }
 
+; FALLBACK-WITH-REPORT-ERR: remark: <unknown>:0:0: unable to translate instruction{{.*}}scalable_alloca
+; FALLBACK-WITH-REPORT-OUT-LABEL: scalable_alloca
+define void @scalable_alloca() #1 {
+  %local0 = alloca <vscale x 16 x i8>
+  load volatile <vscale x 16 x i8>, <vscale x 16 x i8>* %local0
+  ret void
+}
+
 ; FALLBACK-WITH-REPORT-ERR: remark: <unknown>:0:0: unable to translate instruction{{.*}}asm_indirect_output
 ; FALLBACK-WITH-REPORT-OUT-LABEL: asm_indirect_output
 define void @asm_indirect_output() {
Index: llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -14975,6 +14975,11 @@
     if (isa<ScalableVectorType>(Inst.getOperand(i)->getType()))
       return true;
 
+  if (const AllocaInst *AI = dyn_cast<AllocaInst>(&Inst)) {
+    if (isa<ScalableVectorType>(AI->getAllocatedType()))
+      return true;
+  }
+
   return false;
 }
 


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