[InstCombine] Fold select (icmp sgt x, -1), lshr (X, Y), ashr (X, Y) to ashr (X, Y))

Summary:
(select (icmp sgt x, -1), lshr (X, Y), ashr (X, Y)) -> ashr (X, Y))
(select (icmp slt x, 1), ashr (X, Y), lshr (X, Y)) -> ashr (X, Y))

Fixes PR41173

Alive proof by @lebedev.ri (thanks)
Name: PR41173
  %cmp = icmp slt i32 %x, 1
  %shr = lshr i32 %x, %y
  %shr1 = ashr i32 %x, %y
  %retval.0 = select i1 %cmp, i32 %shr1, i32 %shr
  =>
  %retval.0 = ashr i32 %x, %y

Optimization: PR41173
Done: 1
Optimization is correct!

Reviewers: lebedev.ri, spatel

Reviewed By: lebedev.ri

Subscribers: nikic, craig.topper, llvm-commits, lebedev.ri

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64285

llvm-svn: 365893

lib/Transforms/InstCombine/InstCombineSelect.cpp

@@ -531,6 +531,44 @@ static Instruction *foldSelectICmpAndAnd(Type *SelType, const ICmpInst *Cmp,
   return new ZExtInst(ICmpNeZero, SelType);
 }
 
+/// We want to turn:
+///   (select (icmp sgt x, C), lshr (X, Y), ashr (X, Y)); iff C s>= -1
+///   (select (icmp slt x, C), ashr (X, Y), lshr (X, Y)); iff C s>= 0
+/// into:
+///   ashr (X, Y)
+static Value *foldSelectICmpLshrAshr(const ICmpInst *IC, Value *TrueVal,
+                                     Value *FalseVal,
+                                     InstCombiner::BuilderTy &Builder) {
+  ICmpInst::Predicate Pred = IC->getPredicate();
+  Value *CmpLHS = IC->getOperand(0);
+  Value *CmpRHS = IC->getOperand(1);
+
+  Value *X, *Y;
+  unsigned Bitwidth = CmpRHS->getType()->getScalarSizeInBits();
+  if ((Pred != ICmpInst::ICMP_SGT ||
+       !match(CmpRHS,
+              m_SpecificInt_ICMP(ICmpInst::ICMP_SGE, APInt(Bitwidth, -1)))) &&
+      (Pred != ICmpInst::ICMP_SLT ||
+       !match(CmpRHS,
+              m_SpecificInt_ICMP(ICmpInst::ICMP_SGE, APInt(Bitwidth, 0)))))
+    return nullptr;
+
+  // Canonicalize so that ashr is in FalseVal.
+  if (Pred == ICmpInst::ICMP_SLT)
+    std::swap(TrueVal, FalseVal);
+
+  if (match(TrueVal, m_LShr(m_Value(X), m_Value(Y))) &&
+      match(FalseVal, m_AShr(m_Specific(X), m_Specific(Y))) &&
+      match(CmpLHS, m_Specific(X))) {
+    const auto *Ashr = cast<Instruction>(FalseVal);
+    // if lshr is not exact and ashr is, this new ashr must not be exact.
+    bool IsExact = Ashr->isExact() && cast<Instruction>(TrueVal)->isExact();
+    return Builder.CreateAShr(X, Y, IC->getName(), IsExact);
+  }
+
+  return nullptr;
+}
+
 /// We want to turn:
 ///   (select (icmp eq (and X, C1), 0), Y, (or Y, C2))
 /// into:
@@ -1112,6 +1150,9 @@ Instruction *InstCombiner::foldSelectInstWithICmp(SelectInst &SI,
   if (Value *V = foldSelectICmpAndOr(ICI, TrueVal, FalseVal, Builder))
     return replaceInstUsesWith(SI, V);
 
+  if (Value *V = foldSelectICmpLshrAshr(ICI, TrueVal, FalseVal, Builder))
+    return replaceInstUsesWith(SI, V);
+
   if (Value *V = foldSelectCttzCtlz(ICI, TrueVal, FalseVal, Builder))
     return replaceInstUsesWith(SI, V);
 

test/Transforms/InstCombine/ashr-lshr.ll

@@ -3,11 +3,8 @@
 
 define i32 @ashr_lshr_exact_ashr_only(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr_exact_ashr_only(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[X:%.*]], -1
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr i32 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr i32 [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact i32 [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[L]], i32 [[R]]
-; CHECK-NEXT:    ret i32 [[RET]]
 ;
   %cmp = icmp sgt i32 %x, -1
   %l = lshr i32 %x, %y
@@ -18,11 +15,8 @@ define i32 @ashr_lshr_exact_ashr_only(i32 %x, i32 %y) {
 
 define i32 @ashr_lshr_no_exact(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr_no_exact(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[X:%.*]], -1
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr i32 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr i32 [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr i32 [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[L]], i32 [[R]]
-; CHECK-NEXT:    ret i32 [[RET]]
 ;
   %cmp = icmp sgt i32 %x, -1
   %l = lshr i32 %x, %y
@@ -33,11 +27,8 @@ define i32 @ashr_lshr_no_exact(i32 %x, i32 %y) {
 
 define i32 @ashr_lshr_exact_both(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr_exact_both(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[X:%.*]], -1
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr exact i32 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr exact i32 [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact i32 [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[L]], i32 [[R]]
-; CHECK-NEXT:    ret i32 [[RET]]
 ;
   %cmp = icmp sgt i32 %x, -1
   %l = lshr exact i32 %x, %y
@@ -48,11 +39,8 @@ define i32 @ashr_lshr_exact_both(i32 %x, i32 %y) {
 
 define i32 @ashr_lshr_exact_lshr_only(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr_exact_lshr_only(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[X:%.*]], -1
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr i32 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr exact i32 [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr i32 [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[L]], i32 [[R]]
-; CHECK-NEXT:    ret i32 [[RET]]
 ;
   %cmp = icmp sgt i32 %x, -1
   %l = lshr exact i32 %x, %y
@@ -63,11 +51,8 @@ define i32 @ashr_lshr_exact_lshr_only(i32 %x, i32 %y) {
 
 define i32 @ashr_lshr2(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr2(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[X:%.*]], 5
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr i32 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr i32 [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact i32 [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[L]], i32 [[R]]
-; CHECK-NEXT:    ret i32 [[RET]]
 ;
   %cmp = icmp sgt i32 %x, 5
   %l = lshr i32 %x, %y
@@ -78,11 +63,8 @@ define i32 @ashr_lshr2(i32 %x, i32 %y) {
 
 define <2 x i32> @ashr_lshr_splat_vec(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_splat_vec(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i32> [[X:%.*]], <i32 -1, i32 -1>
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr <2 x i32> [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[L]], <2 x i32> [[R]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
 ;
   %cmp = icmp sgt <2 x i32> %x, <i32 -1, i32 -1>
   %l = lshr <2 x i32> %x, %y
@@ -93,11 +75,8 @@ define <2 x i32> @ashr_lshr_splat_vec(<2 x i32> %x, <2 x i32> %y) {
 
 define <2 x i32> @ashr_lshr_splat_vec2(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_splat_vec2(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i32> [[X:%.*]], <i32 -1, i32 -1>
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr exact <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr exact <2 x i32> [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[L]], <2 x i32> [[R]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
 ;
   %cmp = icmp sgt <2 x i32> %x, <i32 -1, i32 -1>
   %l = lshr exact <2 x i32> %x, %y
@@ -108,11 +87,8 @@ define <2 x i32> @ashr_lshr_splat_vec2(<2 x i32> %x, <2 x i32> %y) {
 
 define <2 x i32> @ashr_lshr_splat_vec3(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_splat_vec3(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i32> [[X:%.*]], <i32 -1, i32 -1>
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr exact <2 x i32> [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[L]], <2 x i32> [[R]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
 ;
   %cmp = icmp sgt <2 x i32> %x, <i32 -1, i32 -1>
   %l = lshr exact <2 x i32> %x, %y
@@ -123,11 +99,8 @@ define <2 x i32> @ashr_lshr_splat_vec3(<2 x i32> %x, <2 x i32> %y) {
 
 define <2 x i32> @ashr_lshr_splat_vec4(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_splat_vec4(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i32> [[X:%.*]], <i32 -1, i32 -1>
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr <2 x i32> [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[L]], <2 x i32> [[R]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
 ;
   %cmp = icmp sgt <2 x i32> %x, <i32 -1, i32 -1>
   %l = lshr <2 x i32> %x, %y
@@ -138,11 +111,8 @@ define <2 x i32> @ashr_lshr_splat_vec4(<2 x i32> %x, <2 x i32> %y) {
 
 define <2 x i32> @ashr_lshr_nonsplat_vec(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_nonsplat_vec(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i32> [[X:%.*]], <i32 -1, i32 1>
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr <2 x i32> [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[L]], <2 x i32> [[R]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
 ;
   %cmp = icmp sgt <2 x i32> %x, <i32 -1, i32 1>
   %l = lshr <2 x i32> %x, %y
@@ -153,11 +123,8 @@ define <2 x i32> @ashr_lshr_nonsplat_vec(<2 x i32> %x, <2 x i32> %y) {
 
 define <2 x i32> @ashr_lshr_nonsplat_vec2(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_nonsplat_vec2(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i32> [[X:%.*]], <i32 2, i32 4>
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr exact <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr exact <2 x i32> [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[L]], <2 x i32> [[R]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
 ;
   %cmp = icmp sgt <2 x i32> %x, <i32 2, i32 4>
   %l = lshr exact <2 x i32> %x, %y
@@ -168,11 +135,8 @@ define <2 x i32> @ashr_lshr_nonsplat_vec2(<2 x i32> %x, <2 x i32> %y) {
 
 define <2 x i32> @ashr_lshr_nonsplat_vec3(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_nonsplat_vec3(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i32> [[X:%.*]], <i32 5, i32 6>
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr exact <2 x i32> [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[L]], <2 x i32> [[R]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
 ;
   %cmp = icmp sgt <2 x i32> %x, <i32 5, i32 6>
   %l = lshr exact <2 x i32> %x, %y
@@ -183,11 +147,8 @@ define <2 x i32> @ashr_lshr_nonsplat_vec3(<2 x i32> %x, <2 x i32> %y) {
 
 define <2 x i32> @ashr_lshr_nonsplat_vec4(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_nonsplat_vec4(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i32> [[X:%.*]], <i32 8, i32 7>
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr <2 x i32> [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[L]], <2 x i32> [[R]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
 ;
   %cmp = icmp sgt <2 x i32> %x, <i32 8, i32 7>
   %l = lshr <2 x i32> %x, %y
@@ -198,11 +159,8 @@ define <2 x i32> @ashr_lshr_nonsplat_vec4(<2 x i32> %x, <2 x i32> %y) {
 
 define i32 @ashr_lshr_cst(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr_cst(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[X:%.*]], 1
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr i32 [[X:%.*]], 8
-; CHECK-NEXT:    [[L:%.*]] = lshr i32 [[X]], 8
+; CHECK-NEXT:    ret i32 [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact i32 [[X]], 8
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[R]], i32 [[L]]
-; CHECK-NEXT:    ret i32 [[RET]]
 ;
   %cmp = icmp slt i32 %x, 1
   %l = lshr i32 %x, 8
@@ -213,11 +171,8 @@ define i32 @ashr_lshr_cst(i32 %x, i32 %y) {
 
 define i32 @ashr_lshr_cst2(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr_cst2(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[X:%.*]], -1
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr i32 [[X:%.*]], 8
-; CHECK-NEXT:    [[L:%.*]] = lshr i32 [[X]], 8
+; CHECK-NEXT:    ret i32 [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact i32 [[X]], 8
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[L]], i32 [[R]]
-; CHECK-NEXT:    ret i32 [[RET]]
 ;
   %cmp = icmp sgt i32 %x, -1
   %l = lshr i32 %x, 8
@@ -228,11 +183,8 @@ define i32 @ashr_lshr_cst2(i32 %x, i32 %y) {
 
 define i32 @ashr_lshr_inv(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr_inv(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[X:%.*]], 1
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr i32 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr i32 [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact i32 [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[R]], i32 [[L]]
-; CHECK-NEXT:    ret i32 [[RET]]
 ;
   %cmp = icmp slt i32 %x, 1
   %l = lshr i32 %x, %y
@@ -243,11 +195,8 @@ define i32 @ashr_lshr_inv(i32 %x, i32 %y) {
 
 define i32 @ashr_lshr_inv2(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr_inv2(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[X:%.*]], 7
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr i32 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr i32 [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact i32 [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[R]], i32 [[L]]
-; CHECK-NEXT:    ret i32 [[RET]]
 ;
   %cmp = icmp slt i32 %x, 7
   %l = lshr i32 %x, %y
@@ -258,11 +207,8 @@ define i32 @ashr_lshr_inv2(i32 %x, i32 %y) {
 
 define <2 x i32> @ashr_lshr_inv_splat_vec(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_inv_splat_vec(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt <2 x i32> [[X:%.*]], <i32 1, i32 1>
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr <2 x i32> [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[R]], <2 x i32> [[L]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
 ;
   %cmp = icmp slt <2 x i32> %x, <i32 1, i32 1>
   %l = lshr <2 x i32> %x, %y
@@ -273,11 +219,8 @@ define <2 x i32> @ashr_lshr_inv_splat_vec(<2 x i32> %x, <2 x i32> %y) {
 
 define <2 x i32> @ashr_lshr_inv_nonsplat_vec(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_inv_nonsplat_vec(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt <2 x i32> [[X:%.*]], <i32 4, i32 5>
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr <2 x i32> [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[R]], <2 x i32> [[L]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
 ;
   %cmp = icmp slt <2 x i32> %x, <i32 4, i32 5>
   %l = lshr <2 x i32> %x, %y
@@ -288,11 +231,8 @@ define <2 x i32> @ashr_lshr_inv_nonsplat_vec(<2 x i32> %x, <2 x i32> %y) {
 
 define <2 x i32> @ashr_lshr_vec_undef(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_vec_undef(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i32> [[X:%.*]], <i32 undef, i32 -1>
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr <2 x i32> [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[L]], <2 x i32> [[R]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
 ;
   %cmp = icmp sgt <2 x i32> %x, <i32 undef, i32 -1>
   %l = lshr <2 x i32> %x, %y
@@ -303,11 +243,8 @@ define <2 x i32> @ashr_lshr_vec_undef(<2 x i32> %x, <2 x i32> %y) {
 
 define <2 x i32> @ashr_lshr_vec_undef2(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_vec_undef2(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt <2 x i32> [[X:%.*]], <i32 1, i32 undef>
+; CHECK-NEXT:    [[CMP1:%.*]] = ashr exact <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[L:%.*]] = lshr exact <2 x i32> [[X]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[CMP1]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[R]], <2 x i32> [[L]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
 ;
   %cmp = icmp slt <2 x i32> %x, <i32 1, i32 undef>
   %l = lshr exact <2 x i32> %x, %y