[PATCH] D100463: [AArch64][SVEIntrinsicOpts] Fold sve_convert_from_svbool(zero) to zero

[Joe Ellis via Phabricator via llvm-commits]

joechrisellis created this revision.
joechrisellis added reviewers: paulwalker-arm, kmclaughlin, bsmith, DavidTruby.
Herald added subscribers: hiraditya, kristof.beyls, tschuett.
joechrisellis requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Co-authored-by: Paul Walker <paul.walker at arm.com>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D100463

Files:
  llvm/lib/Target/AArch64/SVEIntrinsicOpts.cpp
  llvm/test/CodeGen/AArch64/sve-intrinsic-opts-reinterpret.ll


Index: llvm/test/CodeGen/AArch64/sve-intrinsic-opts-reinterpret.ll
===================================================================
--- llvm/test/CodeGen/AArch64/sve-intrinsic-opts-reinterpret.ll
+++ llvm/test/CodeGen/AArch64/sve-intrinsic-opts-reinterpret.ll
@@ -251,6 +251,13 @@
   ret <vscale x 16 x i1> %pg
 }
 
+define <vscale x 2 x i1> @reinterpret_zero() {
+; OPT-LABEL:  @reinterpret_zero(
+; OPT: ret <vscale x 2 x i1> zeroinitializer
+  %pg = tail call <vscale x 2 x i1> @llvm.aarch64.sve.convert.from.svbool.nxv2i1(<vscale x 16 x i1> zeroinitializer)
+  ret <vscale x 2 x i1> %pg
+}
+
 declare <vscale x 16 x i1> @llvm.aarch64.sve.convert.to.svbool.nxv8i1(<vscale x 8 x i1>)
 declare <vscale x 16 x i1> @llvm.aarch64.sve.convert.to.svbool.nxv4i1(<vscale x 4 x i1>)
 declare <vscale x 16 x i1> @llvm.aarch64.sve.convert.to.svbool.nxv2i1(<vscale x 2 x i1>)
Index: llvm/lib/Target/AArch64/SVEIntrinsicOpts.cpp
===================================================================
--- llvm/lib/Target/AArch64/SVEIntrinsicOpts.cpp
+++ llvm/lib/Target/AArch64/SVEIntrinsicOpts.cpp
@@ -481,6 +481,15 @@
   if (isa<PHINode>(I->getArgOperand(0)))
     return processPhiNode(I);
 
+  if (auto *C = dyn_cast<Constant>(I->getArgOperand(0))) {
+    if (!C->isNullValue())
+      return false;
+
+    I->replaceAllUsesWith(ConstantInt::getFalse(I->getType()));
+    I->eraseFromParent();
+    return true;
+  }
+
   SmallVector<Instruction *, 32> CandidatesForRemoval;
   Value *Cursor = I->getOperand(0), *EarliestReplacement = nullptr;
 


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