[SVE][InstCombine] Delete redundante sel instructions with ptrue

svsel(pture, x, y) => x. depend on D121792 Reviewed By: paulwalker-arm, david-arm
llvm · Oct 13, 2023 · bf90ffb · bf90ffb
1 parent 127cf4e
commit bf90ffb
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Showing 2 changed files with 24 additions and 21 deletions.
diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -798,10 +798,31 @@ instCombineConvertFromSVBool(InstCombiner &IC, IntrinsicInst &II) {
   return IC.replaceInstUsesWith(II, EarliestReplacement);
 }
 
+static bool isAllActivePredicate(Value *Pred) {
+  // Look through convert.from.svbool(convert.to.svbool(...) chain.
+  Value *UncastedPred;
+  if (match(Pred, m_Intrinsic<Intrinsic::aarch64_sve_convert_from_svbool>(
+                      m_Intrinsic<Intrinsic::aarch64_sve_convert_to_svbool>(
+                          m_Value(UncastedPred)))))
+    // If the predicate has the same or less lanes than the uncasted
+    // predicate then we know the casting has no effect.
+    if (cast<ScalableVectorType>(Pred->getType())->getMinNumElements() <=
+        cast<ScalableVectorType>(UncastedPred->getType())->getMinNumElements())
+      Pred = UncastedPred;
+
+  return match(Pred, m_Intrinsic<Intrinsic::aarch64_sve_ptrue>(
+                         m_ConstantInt<AArch64SVEPredPattern::all>()));
+}
+
 static std::optional<Instruction *> instCombineSVESel(InstCombiner &IC,
                                                       IntrinsicInst &II) {
-  auto Select = IC.Builder.CreateSelect(II.getOperand(0), II.getOperand(1),
-                                        II.getOperand(2));
+  // svsel(ptrue, x, y) => x
+  auto *OpPredicate = II.getOperand(0);
+  if (isAllActivePredicate(OpPredicate))
+    return IC.replaceInstUsesWith(II, II.getOperand(1));
+
+  auto Select =
+      IC.Builder.CreateSelect(OpPredicate, II.getOperand(1), II.getOperand(2));
   return IC.replaceInstUsesWith(II, Select);
 }
 
@@ -1200,22 +1221,6 @@ instCombineSVEVectorFuseMulAddSub(InstCombiner &IC, IntrinsicInst &II,
   return IC.replaceInstUsesWith(II, Res);
 }
 
-static bool isAllActivePredicate(Value *Pred) {
-  // Look through convert.from.svbool(convert.to.svbool(...) chain.
-  Value *UncastedPred;
-  if (match(Pred, m_Intrinsic<Intrinsic::aarch64_sve_convert_from_svbool>(
-                      m_Intrinsic<Intrinsic::aarch64_sve_convert_to_svbool>(
-                          m_Value(UncastedPred)))))
-    // If the predicate has the same or less lanes than the uncasted
-    // predicate then we know the casting has no effect.
-    if (cast<ScalableVectorType>(Pred->getType())->getMinNumElements() <=
-        cast<ScalableVectorType>(UncastedPred->getType())->getMinNumElements())
-      Pred = UncastedPred;
-
-  return match(Pred, m_Intrinsic<Intrinsic::aarch64_sve_ptrue>(
-                         m_ConstantInt<AArch64SVEPredPattern::all>()));
-}
-
 static std::optional<Instruction *>
 instCombineSVELD1(InstCombiner &IC, IntrinsicInst &II, const DataLayout &DL) {
   Value *Pred = II.getOperand(0);

diff --git a/llvm/test/Transforms/InstCombine/AArch64/sve-intrinsic-sel.ll b/llvm/test/Transforms/InstCombine/AArch64/sve-intrinsic-sel.ll
@@ -14,9 +14,7 @@ define <vscale x 4 x i32> @replace_sel_intrinsic(<vscale x 4 x i1> %p, <vscale x
 
 define <vscale x 4 x i32> @sel_ptrue(<vscale x 4 x i32> %a, <vscale x 4 x i32> %b) {
 ; CHECK-LABEL: @sel_ptrue(
-; CHECK-NEXT:    [[PRED:%.*]] = call <vscale x 4 x i1> @llvm.aarch64.sve.ptrue.nxv4i1(i32 31)
-; CHECK-NEXT:    [[RES:%.*]] = select <vscale x 4 x i1> [[PRED]], <vscale x 4 x i32> [[A:%.*]], <vscale x 4 x i32> [[B:%.*]]
-; CHECK-NEXT:    ret <vscale x 4 x i32> [[RES]]
+; CHECK-NEXT:    ret <vscale x 4 x i32> [[A:%.*]]
 ;
   %pred = call <vscale x 4 x i1> @llvm.aarch64.sve.ptrue.nxv4i1(i32 31)
   %res = call <vscale x 4 x i32> @llvm.aarch64.sve.sel.nxv4i32(<vscale x 4 x i1> %pred, <vscale x 4 x i32> %a, <vscale x 4 x i32> %b)