test/Transforms/LoopVectorize/iv-select-cmp.ll - llvm-project/llvm - Git at Google

 ; RUN: opt -passes=loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -S < %s | FileCheck %s --check-prefix=CHECK
 ; RUN: opt -passes=loop-vectorize -force-vector-interleave=4 -force-vector-width=4 -S < %s | FileCheck %s --check-prefix=CHECK
 ; RUN: opt -passes=loop-vectorize -force-vector-interleave=4 -force-vector-width=1 -S < %s | FileCheck %s --check-prefix=CHECK

 define i64 @select_icmp_const_1(ptr %a, i64 %n) {
 ; CHECK-LABEL: define i64 @select_icmp_const_1
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
   %rdx = phi i64 [ %cond, %for.body ], [ 3, %entry ]
   %arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
   %0 = load i64, ptr %arrayidx, align 8
   %cmp2 = icmp eq i64 %0, 3
   %cond = select i1 %cmp2, i64 %iv, i64 %rdx
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, %n
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret i64 %cond
 }

 define i64 @select_icmp_const_2(ptr %a, i64 %n) {
 ; CHECK-LABEL: define i64 @select_icmp_const_2
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
   %rdx = phi i64 [ %cond, %for.body ], [ 3, %entry ]
   %arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
   %0 = load i64, ptr %arrayidx, align 8
   %cmp2 = icmp eq i64 %0, 3
   %cond = select i1 %cmp2, i64 %rdx, i64 %iv
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, %n
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret i64 %cond
 }

 define i64 @select_icmp_const_3_variable_rdx_start(ptr %a, i64 %rdx.start, i64 %n) {
 ; CHECK-LABEL: define i64 @select_icmp_const_3_variable_rdx_start
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
   %rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
   %arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
   %0 = load i64, ptr %arrayidx, align 8
   %cmp2 = icmp eq i64 %0, 3
   %cond = select i1 %cmp2, i64 %iv, i64 %rdx
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, %n
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret i64 %cond
 }

 define i64 @select_fcmp_const_fast(ptr %a, i64 %n) {
 ; CHECK-LABEL: define i64 @select_fcmp_const_fast
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
   %rdx = phi i64 [ %cond, %for.body ], [ 2, %entry ]
   %arrayidx = getelementptr inbounds float, ptr %a, i64 %iv
   %0 = load float, ptr %arrayidx, align 4
   %cmp2 = fcmp fast ueq float %0, 3.0
   %cond = select i1 %cmp2, i64 %iv, i64 %rdx
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, %n
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret i64 %cond
 }

 define i64 @select_fcmp_const(ptr %a, i64 %n) {
 ; CHECK-LABEL: define i64 @select_fcmp_const
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
   %rdx = phi i64 [ %cond, %for.body ], [ 2, %entry ]
   %arrayidx = getelementptr inbounds float, ptr %a, i64 %iv
   %0 = load float, ptr %arrayidx, align 4
   %cmp2 = fcmp ueq float %0, 3.0
   %cond = select i1 %cmp2, i64 %iv, i64 %rdx
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, %n
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret i64 %cond
 }

 define i64 @select_icmp(ptr %a, ptr %b, i64 %rdx.start, i64 %n) {
 ; CHECK-LABEL: define i64 @select_icmp
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
   %rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
   %arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
   %0 = load i64, ptr %arrayidx, align 8
   %arrayidx1 = getelementptr inbounds i64, ptr %b, i64 %iv
   %1 = load i64, ptr %arrayidx1, align 8
   %cmp2 = icmp sgt i64 %0, %1
   %cond = select i1 %cmp2, i64 %iv, i64 %rdx
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, %n
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret i64 %cond
 }

 define i64 @select_fcmp(ptr %a, ptr %b, i64 %rdx.start, i64 %n) {
 ; CHECK-LABEL: define i64 @select_fcmp
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
   %rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
   %arrayidx = getelementptr inbounds float, ptr %a, i64 %iv
   %0 = load float, ptr %arrayidx, align 4
   %arrayidx1 = getelementptr inbounds float, ptr %b, i64 %iv
   %1 = load float, ptr %arrayidx1, align 4
   %cmp2 = fcmp ogt float %0, %1
   %cond = select i1 %cmp2, i64 %iv, i64 %rdx
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, %n
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret i64 %cond
 }

 define i64 @select_icmp_min_valid_iv_start(ptr %a, ptr %b, i64 %rdx.start, i64 %n) {
 ; CHECK-LABEL: define i64 @select_icmp_min_valid_iv_start
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv.j = phi i64 [ %inc3, %for.body ], [ -9223372036854775807, %entry]
   %iv.i = phi i64 [ %inc, %for.body ], [ 0, %entry ]
   %rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
   %arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv.i
   %0 = load i64, ptr %arrayidx, align 8
   %arrayidx1 = getelementptr inbounds i64, ptr %b, i64 %iv.i
   %1 = load i64, ptr %arrayidx1, align 8
   %cmp2 = icmp sgt i64 %0, %1
   %cond = select i1 %cmp2, i64 %iv.j, i64 %rdx
   %inc = add nuw nsw i64 %iv.i, 1
   %inc3 = add nsw i64 %iv.j, 1
   %exitcond.not = icmp eq i64 %inc, %n
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret i64 %cond
 }

 ; Negative tests

 ; This test can theoretically be vectorized without a runtime-check, by
 ; pattern-matching on the constructs that are introduced by IndVarSimplify.
 ; We can check two things:
 ;   %1 = trunc i64 %iv to i32
 ; This indicates that the %iv is truncated to i32. We can then check the loop
 ; guard is a signed i32:
 ;   %cmp.sgt = icmp sgt i32 %n, 0
 ; and successfully vectorize the case without a runtime-check.
 define i32 @not_vectorized_select_icmp_const_truncated_iv_widened_exit(ptr %a, i32 %n) {
 ; CHECK-LABEL: define i32 @not_vectorized_select_icmp_const_truncated_iv_widened_exit
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   %cmp.sgt = icmp sgt i32 %n, 0
   br i1 %cmp.sgt, label %for.body.preheader, label %exit

 for.body.preheader:                               ; preds = %entry
   %wide.trip.count = zext i32 %n to i64
   br label %for.body

 for.body:                                         ; preds = %for.body.preheader, %for.body
   %iv = phi i64 [ 0, %for.body.preheader ], [ %inc, %for.body ]
   %rdx = phi i32 [ 331, %for.body.preheader ], [ %spec.select, %for.body ]
   %arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
   %0 = load i64, ptr %arrayidx, align 8
   %cmp = icmp sgt i64 %0, 3
   %1 = trunc i64 %iv to i32
   %spec.select = select i1 %cmp, i32 %1, i32 %rdx
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, %wide.trip.count
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                            ; preds = %for.body, %entry
   %rdx.lcssa = phi i32 [ 331, %entry ], [ %spec.select, %for.body ]
   ret i32 %rdx.lcssa
 }

 ; This test can theoretically be vectorized without a runtime-check, by
 ; pattern-matching on the constructs that are introduced by IndVarSimplify.
 ; We can check two things:
 ;   %1 = trunc i64 %iv to i32
 ; This indicates that the %iv is truncated to i32. We can then check the loop
 ; exit condition, which compares to a constant that fits within i32:
 ;   %exitcond.not = icmp eq i64 %inc, 20000
 ; and successfully vectorize the case without a runtime-check.
 define i32 @not_vectorized_select_icmp_const_truncated_iv_const_exit(ptr %a) {
 ; CHECK-LABEL: define i32 @not_vectorized_select_icmp_const_truncated_iv_const_exit
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ 0, %entry ], [ %inc, %for.body ]
   %rdx = phi i32 [ 331, %entry ], [ %spec.select, %for.body ]
   %arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
   %0 = load i64, ptr %arrayidx, align 8
   %cmp = icmp sgt i64 %0, 3
   %1 = trunc i64 %iv to i32
   %spec.select = select i1 %cmp, i32 %1, i32 %rdx
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, 20000
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                           ; preds = %for.body
   ret i32 %spec.select
 }

 ; This test can theoretically be vectorized, but only with a runtime-check.
 ; The construct that are introduced by IndVarSimplify is:
 ;   %1 = trunc i64 %iv to i32
 ; However, the loop guard is an i64:
 ;   %cmp.sgt = icmp sgt i64 %n, 0
 ; We cannot guarantee that %iv won't overflow an i32 value (and hence hit the
 ; sentinel value), and need a runtime-check to vectorize this case.
 define i32 @not_vectorized_select_icmp_const_truncated_iv_unwidened_exit(ptr %a, i64 %n) {
 ; CHECK-LABEL: define i32 @not_vectorized_select_icmp_const_truncated_iv_unwidened_exit
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   %cmp.sgt = icmp sgt i64 %n, 0
   br i1 %cmp.sgt, label %for.body, label %exit

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ 0, %entry ], [ %inc, %for.body ]
   %rdx = phi i32 [ 331, %entry ], [ %spec.select, %for.body ]
   %arrayidx = getelementptr inbounds i32, ptr %a, i64 %iv
   %0 = load i32, ptr %arrayidx, align 4
   %cmp = icmp sgt i32 %0, 3
   %1 = trunc i64 %iv to i32
   %spec.select = select i1 %cmp, i32 %1, i32 %rdx
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, %n
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body, %entry
   %rdx.lcssa = phi i32 [ 331, %entry ], [ %spec.select, %for.body ]
   ret i32 %rdx.lcssa
 }

 ; This test can theoretically be vectorized, but only with a runtime-check.
 ; The construct that are introduced by IndVarSimplify is:
 ;   %1 = trunc i64 %iv to i32
 ; However, the loop guard is unsigned:
 ;   %cmp.not = icmp eq i32 %n, 0
 ; We cannot guarantee that %iv won't overflow an i32 value (and hence hit the
 ; sentinel value), and need a runtime-check to vectorize this case.
 define i32 @not_vectorized_select_icmp_const_truncated_iv_unsigned_loop_guard(ptr %a, i32 %n) {
 ; CHECK-LABEL: define i32 @not_vectorized_select_icmp_const_truncated_iv_unsigned_loop_guard
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   %cmp.not = icmp eq i32 %n, 0
   br i1 %cmp.not, label %exit, label %for.body.preheader

 for.body.preheader:                               ; preds = %entry
   %wide.trip.count = zext i32 %n to i64
   br label %for.body

 for.body:                                         ; preds = %for.body.preheader, %for.body
   %iv = phi i64 [ 0, %for.body.preheader ], [ %inc, %for.body ]
   %rdx = phi i32 [ 331, %for.body.preheader ], [ %spec.select, %for.body ]
   %arrayidx = getelementptr inbounds i32, ptr %a, i64 %iv
   %0 = load i32, ptr %arrayidx, align 4
   %cmp1 = icmp sgt i32 %0, 3
   %1 = trunc i64 %iv to i32
   %spec.select = select i1 %cmp1, i32 %1, i32 %rdx
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, %wide.trip.count
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body, %entry
   %rdx.lcssa = phi i32 [ 331, %entry ], [ %spec.select, %for.body ]
   ret i32 %rdx.lcssa
 }

 ; This test cannot be vectorized, even with a runtime check.
 ; The construct that are introduced by IndVarSimplify is:
 ;   %1 = trunc i64 %iv to i32
 ; However, the loop exit condition is a constant that overflows i32:
 ;   %exitcond.not = icmp eq i64 %inc, 4294967294
 ; Hence, the i32 will most certainly wrap and hit the sentinel value, and we
 ; cannot vectorize this case.
 define i32 @not_vectorized_select_icmp_truncated_iv_out_of_bound(ptr %a) {
 ; CHECK-LABEL: define i32 @not_vectorized_select_icmp_truncated_iv_out_of_bound
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ 2147483646, %entry ], [ %inc, %for.body ]
   %rdx = phi i32 [ 331, %entry ], [ %spec.select, %for.body ]
   %arrayidx = getelementptr inbounds i32, ptr %a, i64 %iv
   %0 = load i32, ptr %arrayidx, align 4
   %cmp = icmp sgt i32 %0, 3
   %conv = trunc i64 %iv to i32
   %spec.select = select i1 %cmp, i32 %conv, i32 %rdx
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, 4294967294
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret i32 %spec.select
 }

 define float @not_vectorized_select_float_induction_icmp(ptr %a, ptr %b, float %rdx.start, i64 %n) {
 ; CHECK-LABEL: @not_vectorized_select_float_induction_icmp
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
   %fiv = phi float [ %conv3, %for.body ], [ 0.000000e+00, %entry ]
   %rdx = phi float [ %cond, %for.body ], [ %rdx.start, %entry ]
   %arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
   %0 = load i64, ptr %arrayidx, align 8
   %arrayidx1 = getelementptr inbounds i64, ptr %b, i64 %iv
   %1 = load i64, ptr %arrayidx1, align 8
   %cmp2 = icmp sgt i64 %0, %1
   %cond = select i1 %cmp2, float %fiv, float %rdx
   %conv3 = fadd float %fiv, 1.000000e+00
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, %n
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret float %cond
 }

 define i64 @not_vectorized_select_decreasing_induction_icmp_const_start(ptr %a) {
 ; CHECK-LABEL: @not_vectorized_select_decreasing_induction_icmp_const_start
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ 19999, %entry ], [ %dec, %for.body ]
   %rdx = phi i64 [ 331, %entry ], [ %spec.select, %for.body ]
   %arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
   %0 = load i64, ptr %arrayidx, align 8
   %cmp = icmp sgt i64 %0, 3
   %spec.select = select i1 %cmp, i64 %iv, i64 %rdx
   %dec = add nsw i64 %iv, -1
   %cmp.not = icmp eq i64 %iv, 0
   br i1 %cmp.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret i64 %spec.select
 }

 define i64 @not_vectorized_select_decreasing_induction_icmp_non_const_start(ptr %a, ptr %b, i64 %rdx.start, i64 %n) {
 ; CHECK-LABEL: @not_vectorized_select_decreasing_induction_icmp_non_const_start
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %i.0.in10 = phi i64 [ %iv, %for.body ], [ %n, %entry ]
   %rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
   %iv = add nsw i64 %i.0.in10, -1
   %arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
   %0 = load i64, ptr %arrayidx, align 8
   %arrayidx1 = getelementptr inbounds i64, ptr %b, i64 %iv
   %1 = load i64, ptr %arrayidx1, align 8
   %cmp2 = icmp sgt i64 %0, %1
   %cond = select i1 %cmp2, i64 %iv, i64 %rdx
   %cmp = icmp ugt i64 %i.0.in10, 1
   br i1 %cmp, label %for.body, label %exit

 exit:                                             ; preds = %for.body
   ret i64 %cond
 }

 ; The sentinel value for increasing-IV vectorization is -LONG_MAX, and since
 ; the IV hits this value, it is impossible to vectorize this case.
 define i64 @not_vectorized_select_icmp_iv_out_of_bound(ptr %a, ptr %b, i64 %rdx.start, i64 %n) {
 ; CHECK-LABEL: @not_vectorized_select_icmp_iv_out_of_bound
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv.j = phi i64 [ %inc3, %for.body ], [ -9223372036854775808, %entry]
   %iv.i = phi i64 [ %inc, %for.body ], [ 0, %entry ]
   %rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
   %arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv.i
   %0 = load i64, ptr %arrayidx, align 8
   %arrayidx1 = getelementptr inbounds i64, ptr %b, i64 %iv.i
   %1 = load i64, ptr %arrayidx1, align 8
   %cmp2 = icmp sgt i64 %0, %1
   %cond = select i1 %cmp2, i64 %iv.j, i64 %rdx
   %inc = add nuw nsw i64 %iv.i, 1
   %inc3 = add nsw i64 %iv.j, 1
   %exitcond.not = icmp eq i64 %inc, %n
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret i64 %cond
 }

 ; The sentinel value for decreasing-IV vectorization is LONG_MAX, and since
 ; the IV hits this value, it is impossible to vectorize this case.
 define i64 @not_vectorized_select_decreasing_induction_icmp_iv_out_of_bound(ptr %a) {
 ; CHECK-LABEL: @not_vectorized_select_decreasing_induction_icmp_iv_out_of_bound
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ 9223372036854775807, %entry ], [ %dec, %for.body ]
   %rdx = phi i64 [ 331, %entry ], [ %spec.select, %for.body ]
   %arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
   %0 = load i64, ptr %arrayidx, align 8
   %cmp1 = icmp sgt i64 %0, 3
   %spec.select = select i1 %cmp1, i64 %iv, i64 %rdx
   %dec = add nsw i64 %iv, -1
   %cmp.not = icmp eq i64 %iv, 0
   br i1 %cmp.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret i64 %spec.select
 }

 define i64 @not_vectorized_select_icmp_non_const_iv_start_value(ptr %a, ptr %b, i64 %ivstart, i64 %rdx.start, i64 %n) {
 ; CHECK-LABEL: define i64 @not_vectorized_select_icmp_non_const_iv_start_value
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %for.body

 for.body:                                         ; preds = %entry, %for.body
   %iv = phi i64 [ %inc, %for.body ], [ %ivstart, %entry ]
   %rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
   %arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
   %0 = load i64, ptr %arrayidx, align 8
   %arrayidx1 = getelementptr inbounds i64, ptr %b, i64 %iv
   %1 = load i64, ptr %arrayidx1, align 8
   %cmp2 = icmp sgt i64 %0, %1
   %cond = select i1 %cmp2, i64 %iv, i64 %rdx
   %inc = add nuw nsw i64 %iv, 1
   %exitcond.not = icmp eq i64 %inc, %n
   br i1 %exitcond.not, label %exit, label %for.body

 exit:                                             ; preds = %for.body
   ret i64 %cond
 }
	; RUN: opt -passes=loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -S < %s \| FileCheck %s --check-prefix=CHECK
	; RUN: opt -passes=loop-vectorize -force-vector-interleave=4 -force-vector-width=4 -S < %s \| FileCheck %s --check-prefix=CHECK
	; RUN: opt -passes=loop-vectorize -force-vector-interleave=4 -force-vector-width=1 -S < %s \| FileCheck %s --check-prefix=CHECK

	define i64 @select_icmp_const_1(ptr %a, i64 %n) {
	; CHECK-LABEL: define i64 @select_icmp_const_1
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
	%rdx = phi i64 [ %cond, %for.body ], [ 3, %entry ]
	%arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
	%0 = load i64, ptr %arrayidx, align 8
	%cmp2 = icmp eq i64 %0, 3
	%cond = select i1 %cmp2, i64 %iv, i64 %rdx
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, %n
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i64 %cond
	}

	define i64 @select_icmp_const_2(ptr %a, i64 %n) {
	; CHECK-LABEL: define i64 @select_icmp_const_2
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
	%rdx = phi i64 [ %cond, %for.body ], [ 3, %entry ]
	%arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
	%0 = load i64, ptr %arrayidx, align 8
	%cmp2 = icmp eq i64 %0, 3
	%cond = select i1 %cmp2, i64 %rdx, i64 %iv
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, %n
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i64 %cond
	}

	define i64 @select_icmp_const_3_variable_rdx_start(ptr %a, i64 %rdx.start, i64 %n) {
	; CHECK-LABEL: define i64 @select_icmp_const_3_variable_rdx_start
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
	%rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
	%arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
	%0 = load i64, ptr %arrayidx, align 8
	%cmp2 = icmp eq i64 %0, 3
	%cond = select i1 %cmp2, i64 %iv, i64 %rdx
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, %n
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i64 %cond
	}

	define i64 @select_fcmp_const_fast(ptr %a, i64 %n) {
	; CHECK-LABEL: define i64 @select_fcmp_const_fast
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
	%rdx = phi i64 [ %cond, %for.body ], [ 2, %entry ]
	%arrayidx = getelementptr inbounds float, ptr %a, i64 %iv
	%0 = load float, ptr %arrayidx, align 4
	%cmp2 = fcmp fast ueq float %0, 3.0
	%cond = select i1 %cmp2, i64 %iv, i64 %rdx
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, %n
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i64 %cond
	}

	define i64 @select_fcmp_const(ptr %a, i64 %n) {
	; CHECK-LABEL: define i64 @select_fcmp_const
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
	%rdx = phi i64 [ %cond, %for.body ], [ 2, %entry ]
	%arrayidx = getelementptr inbounds float, ptr %a, i64 %iv
	%0 = load float, ptr %arrayidx, align 4
	%cmp2 = fcmp ueq float %0, 3.0
	%cond = select i1 %cmp2, i64 %iv, i64 %rdx
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, %n
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i64 %cond
	}

	define i64 @select_icmp(ptr %a, ptr %b, i64 %rdx.start, i64 %n) {
	; CHECK-LABEL: define i64 @select_icmp
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
	%rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
	%arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
	%0 = load i64, ptr %arrayidx, align 8
	%arrayidx1 = getelementptr inbounds i64, ptr %b, i64 %iv
	%1 = load i64, ptr %arrayidx1, align 8
	%cmp2 = icmp sgt i64 %0, %1
	%cond = select i1 %cmp2, i64 %iv, i64 %rdx
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, %n
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i64 %cond
	}

	define i64 @select_fcmp(ptr %a, ptr %b, i64 %rdx.start, i64 %n) {
	; CHECK-LABEL: define i64 @select_fcmp
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
	%rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
	%arrayidx = getelementptr inbounds float, ptr %a, i64 %iv
	%0 = load float, ptr %arrayidx, align 4
	%arrayidx1 = getelementptr inbounds float, ptr %b, i64 %iv
	%1 = load float, ptr %arrayidx1, align 4
	%cmp2 = fcmp ogt float %0, %1
	%cond = select i1 %cmp2, i64 %iv, i64 %rdx
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, %n
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i64 %cond
	}

	define i64 @select_icmp_min_valid_iv_start(ptr %a, ptr %b, i64 %rdx.start, i64 %n) {
	; CHECK-LABEL: define i64 @select_icmp_min_valid_iv_start
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv.j = phi i64 [ %inc3, %for.body ], [ -9223372036854775807, %entry]
	%iv.i = phi i64 [ %inc, %for.body ], [ 0, %entry ]
	%rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
	%arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv.i
	%0 = load i64, ptr %arrayidx, align 8
	%arrayidx1 = getelementptr inbounds i64, ptr %b, i64 %iv.i
	%1 = load i64, ptr %arrayidx1, align 8
	%cmp2 = icmp sgt i64 %0, %1
	%cond = select i1 %cmp2, i64 %iv.j, i64 %rdx
	%inc = add nuw nsw i64 %iv.i, 1
	%inc3 = add nsw i64 %iv.j, 1
	%exitcond.not = icmp eq i64 %inc, %n
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i64 %cond
	}

	; Negative tests

	; This test can theoretically be vectorized without a runtime-check, by
	; pattern-matching on the constructs that are introduced by IndVarSimplify.
	; We can check two things:
	; %1 = trunc i64 %iv to i32
	; This indicates that the %iv is truncated to i32. We can then check the loop
	; guard is a signed i32:
	; %cmp.sgt = icmp sgt i32 %n, 0
	; and successfully vectorize the case without a runtime-check.
	define i32 @not_vectorized_select_icmp_const_truncated_iv_widened_exit(ptr %a, i32 %n) {
	; CHECK-LABEL: define i32 @not_vectorized_select_icmp_const_truncated_iv_widened_exit
	; CHECK-NOT: vector.body:
	;
	entry:
	%cmp.sgt = icmp sgt i32 %n, 0
	br i1 %cmp.sgt, label %for.body.preheader, label %exit

	for.body.preheader: ; preds = %entry
	%wide.trip.count = zext i32 %n to i64
	br label %for.body

	for.body: ; preds = %for.body.preheader, %for.body
	%iv = phi i64 [ 0, %for.body.preheader ], [ %inc, %for.body ]
	%rdx = phi i32 [ 331, %for.body.preheader ], [ %spec.select, %for.body ]
	%arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
	%0 = load i64, ptr %arrayidx, align 8
	%cmp = icmp sgt i64 %0, 3
	%1 = trunc i64 %iv to i32
	%spec.select = select i1 %cmp, i32 %1, i32 %rdx
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, %wide.trip.count
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body, %entry
	%rdx.lcssa = phi i32 [ 331, %entry ], [ %spec.select, %for.body ]
	ret i32 %rdx.lcssa
	}

	; This test can theoretically be vectorized without a runtime-check, by
	; pattern-matching on the constructs that are introduced by IndVarSimplify.
	; We can check two things:
	; %1 = trunc i64 %iv to i32
	; This indicates that the %iv is truncated to i32. We can then check the loop
	; exit condition, which compares to a constant that fits within i32:
	; %exitcond.not = icmp eq i64 %inc, 20000
	; and successfully vectorize the case without a runtime-check.
	define i32 @not_vectorized_select_icmp_const_truncated_iv_const_exit(ptr %a) {
	; CHECK-LABEL: define i32 @not_vectorized_select_icmp_const_truncated_iv_const_exit
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ 0, %entry ], [ %inc, %for.body ]
	%rdx = phi i32 [ 331, %entry ], [ %spec.select, %for.body ]
	%arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
	%0 = load i64, ptr %arrayidx, align 8
	%cmp = icmp sgt i64 %0, 3
	%1 = trunc i64 %iv to i32
	%spec.select = select i1 %cmp, i32 %1, i32 %rdx
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, 20000
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i32 %spec.select
	}

	; This test can theoretically be vectorized, but only with a runtime-check.
	; The construct that are introduced by IndVarSimplify is:
	; %1 = trunc i64 %iv to i32
	; However, the loop guard is an i64:
	; %cmp.sgt = icmp sgt i64 %n, 0
	; We cannot guarantee that %iv won't overflow an i32 value (and hence hit the
	; sentinel value), and need a runtime-check to vectorize this case.
	define i32 @not_vectorized_select_icmp_const_truncated_iv_unwidened_exit(ptr %a, i64 %n) {
	; CHECK-LABEL: define i32 @not_vectorized_select_icmp_const_truncated_iv_unwidened_exit
	; CHECK-NOT: vector.body:
	;
	entry:
	%cmp.sgt = icmp sgt i64 %n, 0
	br i1 %cmp.sgt, label %for.body, label %exit

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ 0, %entry ], [ %inc, %for.body ]
	%rdx = phi i32 [ 331, %entry ], [ %spec.select, %for.body ]
	%arrayidx = getelementptr inbounds i32, ptr %a, i64 %iv
	%0 = load i32, ptr %arrayidx, align 4
	%cmp = icmp sgt i32 %0, 3
	%1 = trunc i64 %iv to i32
	%spec.select = select i1 %cmp, i32 %1, i32 %rdx
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, %n
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body, %entry
	%rdx.lcssa = phi i32 [ 331, %entry ], [ %spec.select, %for.body ]
	ret i32 %rdx.lcssa
	}

	; This test can theoretically be vectorized, but only with a runtime-check.
	; The construct that are introduced by IndVarSimplify is:
	; %1 = trunc i64 %iv to i32
	; However, the loop guard is unsigned:
	; %cmp.not = icmp eq i32 %n, 0
	; We cannot guarantee that %iv won't overflow an i32 value (and hence hit the
	; sentinel value), and need a runtime-check to vectorize this case.
	define i32 @not_vectorized_select_icmp_const_truncated_iv_unsigned_loop_guard(ptr %a, i32 %n) {
	; CHECK-LABEL: define i32 @not_vectorized_select_icmp_const_truncated_iv_unsigned_loop_guard
	; CHECK-NOT: vector.body:
	;
	entry:
	%cmp.not = icmp eq i32 %n, 0
	br i1 %cmp.not, label %exit, label %for.body.preheader

	for.body.preheader: ; preds = %entry
	%wide.trip.count = zext i32 %n to i64
	br label %for.body

	for.body: ; preds = %for.body.preheader, %for.body
	%iv = phi i64 [ 0, %for.body.preheader ], [ %inc, %for.body ]
	%rdx = phi i32 [ 331, %for.body.preheader ], [ %spec.select, %for.body ]
	%arrayidx = getelementptr inbounds i32, ptr %a, i64 %iv
	%0 = load i32, ptr %arrayidx, align 4
	%cmp1 = icmp sgt i32 %0, 3
	%1 = trunc i64 %iv to i32
	%spec.select = select i1 %cmp1, i32 %1, i32 %rdx
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, %wide.trip.count
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body, %entry
	%rdx.lcssa = phi i32 [ 331, %entry ], [ %spec.select, %for.body ]
	ret i32 %rdx.lcssa
	}

	; This test cannot be vectorized, even with a runtime check.
	; The construct that are introduced by IndVarSimplify is:
	; %1 = trunc i64 %iv to i32
	; However, the loop exit condition is a constant that overflows i32:
	; %exitcond.not = icmp eq i64 %inc, 4294967294
	; Hence, the i32 will most certainly wrap and hit the sentinel value, and we
	; cannot vectorize this case.
	define i32 @not_vectorized_select_icmp_truncated_iv_out_of_bound(ptr %a) {
	; CHECK-LABEL: define i32 @not_vectorized_select_icmp_truncated_iv_out_of_bound
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ 2147483646, %entry ], [ %inc, %for.body ]
	%rdx = phi i32 [ 331, %entry ], [ %spec.select, %for.body ]
	%arrayidx = getelementptr inbounds i32, ptr %a, i64 %iv
	%0 = load i32, ptr %arrayidx, align 4
	%cmp = icmp sgt i32 %0, 3
	%conv = trunc i64 %iv to i32
	%spec.select = select i1 %cmp, i32 %conv, i32 %rdx
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, 4294967294
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i32 %spec.select
	}

	define float @not_vectorized_select_float_induction_icmp(ptr %a, ptr %b, float %rdx.start, i64 %n) {
	; CHECK-LABEL: @not_vectorized_select_float_induction_icmp
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ %inc, %for.body ], [ 0, %entry ]
	%fiv = phi float [ %conv3, %for.body ], [ 0.000000e+00, %entry ]
	%rdx = phi float [ %cond, %for.body ], [ %rdx.start, %entry ]
	%arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
	%0 = load i64, ptr %arrayidx, align 8
	%arrayidx1 = getelementptr inbounds i64, ptr %b, i64 %iv
	%1 = load i64, ptr %arrayidx1, align 8
	%cmp2 = icmp sgt i64 %0, %1
	%cond = select i1 %cmp2, float %fiv, float %rdx
	%conv3 = fadd float %fiv, 1.000000e+00
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, %n
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret float %cond
	}

	define i64 @not_vectorized_select_decreasing_induction_icmp_const_start(ptr %a) {
	; CHECK-LABEL: @not_vectorized_select_decreasing_induction_icmp_const_start
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ 19999, %entry ], [ %dec, %for.body ]
	%rdx = phi i64 [ 331, %entry ], [ %spec.select, %for.body ]
	%arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
	%0 = load i64, ptr %arrayidx, align 8
	%cmp = icmp sgt i64 %0, 3
	%spec.select = select i1 %cmp, i64 %iv, i64 %rdx
	%dec = add nsw i64 %iv, -1
	%cmp.not = icmp eq i64 %iv, 0
	br i1 %cmp.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i64 %spec.select
	}

	define i64 @not_vectorized_select_decreasing_induction_icmp_non_const_start(ptr %a, ptr %b, i64 %rdx.start, i64 %n) {
	; CHECK-LABEL: @not_vectorized_select_decreasing_induction_icmp_non_const_start
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%i.0.in10 = phi i64 [ %iv, %for.body ], [ %n, %entry ]
	%rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
	%iv = add nsw i64 %i.0.in10, -1
	%arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
	%0 = load i64, ptr %arrayidx, align 8
	%arrayidx1 = getelementptr inbounds i64, ptr %b, i64 %iv
	%1 = load i64, ptr %arrayidx1, align 8
	%cmp2 = icmp sgt i64 %0, %1
	%cond = select i1 %cmp2, i64 %iv, i64 %rdx
	%cmp = icmp ugt i64 %i.0.in10, 1
	br i1 %cmp, label %for.body, label %exit

	exit: ; preds = %for.body
	ret i64 %cond
	}

	; The sentinel value for increasing-IV vectorization is -LONG_MAX, and since
	; the IV hits this value, it is impossible to vectorize this case.
	define i64 @not_vectorized_select_icmp_iv_out_of_bound(ptr %a, ptr %b, i64 %rdx.start, i64 %n) {
	; CHECK-LABEL: @not_vectorized_select_icmp_iv_out_of_bound
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv.j = phi i64 [ %inc3, %for.body ], [ -9223372036854775808, %entry]
	%iv.i = phi i64 [ %inc, %for.body ], [ 0, %entry ]
	%rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
	%arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv.i
	%0 = load i64, ptr %arrayidx, align 8
	%arrayidx1 = getelementptr inbounds i64, ptr %b, i64 %iv.i
	%1 = load i64, ptr %arrayidx1, align 8
	%cmp2 = icmp sgt i64 %0, %1
	%cond = select i1 %cmp2, i64 %iv.j, i64 %rdx
	%inc = add nuw nsw i64 %iv.i, 1
	%inc3 = add nsw i64 %iv.j, 1
	%exitcond.not = icmp eq i64 %inc, %n
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i64 %cond
	}

	; The sentinel value for decreasing-IV vectorization is LONG_MAX, and since
	; the IV hits this value, it is impossible to vectorize this case.
	define i64 @not_vectorized_select_decreasing_induction_icmp_iv_out_of_bound(ptr %a) {
	; CHECK-LABEL: @not_vectorized_select_decreasing_induction_icmp_iv_out_of_bound
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ 9223372036854775807, %entry ], [ %dec, %for.body ]
	%rdx = phi i64 [ 331, %entry ], [ %spec.select, %for.body ]
	%arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
	%0 = load i64, ptr %arrayidx, align 8
	%cmp1 = icmp sgt i64 %0, 3
	%spec.select = select i1 %cmp1, i64 %iv, i64 %rdx
	%dec = add nsw i64 %iv, -1
	%cmp.not = icmp eq i64 %iv, 0
	br i1 %cmp.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i64 %spec.select
	}

	define i64 @not_vectorized_select_icmp_non_const_iv_start_value(ptr %a, ptr %b, i64 %ivstart, i64 %rdx.start, i64 %n) {
	; CHECK-LABEL: define i64 @not_vectorized_select_icmp_non_const_iv_start_value
	; CHECK-NOT: vector.body:
	;
	entry:
	br label %for.body

	for.body: ; preds = %entry, %for.body
	%iv = phi i64 [ %inc, %for.body ], [ %ivstart, %entry ]
	%rdx = phi i64 [ %cond, %for.body ], [ %rdx.start, %entry ]
	%arrayidx = getelementptr inbounds i64, ptr %a, i64 %iv
	%0 = load i64, ptr %arrayidx, align 8
	%arrayidx1 = getelementptr inbounds i64, ptr %b, i64 %iv
	%1 = load i64, ptr %arrayidx1, align 8
	%cmp2 = icmp sgt i64 %0, %1
	%cond = select i1 %cmp2, i64 %iv, i64 %rdx
	%inc = add nuw nsw i64 %iv, 1
	%exitcond.not = icmp eq i64 %inc, %n
	br i1 %exitcond.not, label %exit, label %for.body

	exit: ; preds = %for.body
	ret i64 %cond
	}