[LV] Change the test cases to ensure that the trip count is not zero. (NFC)

[Mel-Chen]

ping

[fhahn]

LGTM, thanks!

[Ayal]

llvm/test/Transforms/LoopVectorize/select-min-index.ll

23

Note that checking if %iv.next is zero after bumping it with no-wrap flags (having initialized it to zero) is undefined. As is the case now if %n is zero.

[Mel-Chen]

llvm/test/Transforms/LoopVectorize/select-min-index.ll

23

If %n is less than or equal to 0, the loop will result in an infinite loop. To handle such cases, what else can I do for these cases? Maybe adding a loop guard to ensure that %n is greater than 0?

llvm/test/Transforms/LoopVectorize/select-min-index.ll

 ; RUN: opt -passes=loop-vectorize -force-vector-width=4 -force-vector-interleave=1 -S %s | FileCheck %s
 ; RUN: opt -passes=loop-vectorize -force-vector-width=4 -force-vector-interleave=2 -S %s | FileCheck %s
 ; RUN: opt -passes=loop-vectorize -force-vector-width=1 -force-vector-interleave=2 -S %s | FileCheck %s
 
 ; Test cases for selecting the index with the minimum value.
 
-define i64 @test_vectorize_select_umin_idx(ptr %src) {
+define i64 @test_vectorize_select_umin_idx(ptr %src, i64 %n) {
 ; CHECK-LABEL: @test_vectorize_select_umin_idx(
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %loop
 
 loop:
   %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
   %min.idx = phi i64 [ 0, %entry ], [ %min.idx.next, %loop ]
   %min.val = phi i64 [ 0, %entry ], [ %min.val.next, %loop ]
   %gep = getelementptr i64, ptr %src, i64 %iv
   %l = load i64, ptr %gep
   %cmp = icmp ugt i64 %min.val, %l
   %min.val.next = tail call i64 @llvm.umin.i64(i64 %min.val, i64 %l)
   %min.idx.next = select i1 %cmp, i64 %iv, i64 %min.idx
   %iv.next = add nuw nsw i64 %iv, 1
-  %exitcond.not = icmp eq i64 %iv.next, 0
+  %exitcond.not = icmp eq i64 %iv.next, %n
   br i1 %exitcond.not, label %exit, label %loop
 
 exit:
   %res = phi i64 [ %min.idx.next, %loop ]
   ret i64 %res
 }
 
-define i64 @test_vectorize_select_umin_idx_all_exit_inst(ptr %src, ptr %umin) {
+define i64 @test_vectorize_select_umin_idx_all_exit_inst(ptr %src, ptr %umin, i64 %n) {
 ; CHECK-LABEL: @test_vectorize_select_umin_idx_all_exit_inst(
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %loop
 
 loop:
   %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
   %min.idx = phi i64 [ 0, %entry ], [ %min.idx.next, %loop ]
   %min.val = phi i64 [ 0, %entry ], [ %min.val.next, %loop ]
   %gep = getelementptr i64, ptr %src, i64 %iv
   %l = load i64, ptr %gep
   %cmp = icmp ugt i64 %min.val, %l
   %min.val.next = tail call i64 @llvm.umin.i64(i64 %min.val, i64 %l)
   %min.idx.next = select i1 %cmp, i64 %iv, i64 %min.idx
   %iv.next = add nuw nsw i64 %iv, 1
-  %exitcond.not = icmp eq i64 %iv.next, 0
+  %exitcond.not = icmp eq i64 %iv.next, %n
   br i1 %exitcond.not, label %exit, label %loop
 
 exit:
   %res = phi i64 [ %min.idx.next, %loop ]
   %res.umin = phi i64 [ %min.val.next, %loop ]
   store i64 %res.umin, ptr %umin
   ret i64 %res
 }
 
-define i64 @test_vectorize_select_umin_idx_min_ops_switched(ptr %src) {
+define i64 @test_vectorize_select_umin_idx_min_ops_switched(ptr %src, i64 %n) {
 ; CHECK-LABEL: @test_vectorize_select_umin_idx_min_ops_switched(
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %loop
 
 loop:
   %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
   %min.idx = phi i64 [ 0, %entry ], [ %min.idx.next, %loop ]
   %min.val = phi i64 [ 0, %entry ], [ %min.val.next, %loop ]
   %gep = getelementptr i64, ptr %src, i64 %iv
   %l = load i64, ptr %gep
   %cmp = icmp ugt i64 %min.val, %l
   %min.val.next = tail call i64 @llvm.umin.i64(i64 %l, i64 %min.val)
   %min.idx.next = select i1 %cmp, i64 %iv, i64 %min.idx
   %iv.next = add nuw nsw i64 %iv, 1
-  %exitcond.not = icmp eq i64 %iv.next, 0
+  %exitcond.not = icmp eq i64 %iv.next, %n
   br i1 %exitcond.not, label %exit, label %loop
 
 exit:
   %res = phi i64 [ %min.idx.next, %loop ]
   ret i64 %res
 }
 
-define i64 @test_not_vectorize_select_no_min_reduction(ptr %src) {
+define i64 @test_not_vectorize_select_no_min_reduction(ptr %src, i64 %n) {
 ; CHECK-LABEL: @test_not_vectorize_select_no_min_reduction(
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %loop
 
 loop:
   %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
   %min.idx = phi i64 [ 0, %entry ], [ %min.idx.next, %loop ]
   %min.val = phi i64 [ 0, %entry ], [ %min.val.next, %loop ]
   %gep = getelementptr i64, ptr %src, i64 %iv
   %l = load i64, ptr %gep
   %cmp = icmp ugt i64 %min.val, %l
   %min.val.next = add i64 %l, 1
   %foo = call i64 @llvm.umin.i64(i64 %min.val, i64 %l)
   %min.idx.next = select i1 %cmp, i64 %iv, i64 %min.idx
   %iv.next = add nuw nsw i64 %iv, 1
-  %exitcond.not = icmp eq i64 %iv.next, 0
+  %exitcond.not = icmp eq i64 %iv.next, %n
   br i1 %exitcond.not, label %exit, label %loop
 
 exit:
   %res = phi i64 [ %min.idx.next, %loop ]
   ret i64 %res
 }
 
 
-define i64 @test_not_vectorize_cmp_value(i64 %x) {
+define i64 @test_not_vectorize_cmp_value(i64 %x, i64 %n) {
 ; CHECK-LABEL: @test_not_vectorize_cmp_value(
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %loop
 
 loop:
   %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
   %min.idx = phi i64 [ 0, %entry ], [ %min.idx.next, %loop ]
   %min.val = phi i64 [ 0, %entry ], [ %min.val.next, %loop ]
   %cmp = icmp ugt i64 %min.val, %x
   %min.val.next = tail call i64 @llvm.umin.i64(i64 %min.val, i64 0)
   %min.idx.next = select i1 %cmp, i64 %iv, i64 %min.idx
   %iv.next = add nuw nsw i64 %iv, 1
-  %exitcond.not = icmp eq i64 %iv.next, 0
+  %exitcond.not = icmp eq i64 %iv.next, %n
   br i1 %exitcond.not, label %exit, label %loop
 
 exit:
   %res = phi i64 [ %min.idx.next, %loop ]
   ret i64 %res
 }
 
-define i32 @test_vectorize_select_umin_idx_with_trunc() {
+define i32 @test_vectorize_select_umin_idx_with_trunc(i64 %n) {
 ; CHECK-LABEL: @test_vectorize_select_umin_idx_with_trunc(
 ; CHECK-NOT:   vector.body:
 ;
 entry:
   br label %loop
 
 loop:
   %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
   %min.idx = phi i32 [ 0, %entry ], [ %min.idx.next, %loop ]
   %min.val = phi i64 [ 0, %entry ], [ %min.val.next, %loop ]
   %cmp = icmp ugt i64 %min.val, 0
   %min.val.next = tail call i64 @llvm.umin.i64(i64 %min.val, i64 0)
   %trunc = trunc i64 %iv to i32
   %min.idx.next = select i1 %cmp, i32 %trunc, i32 %min.idx
   %iv.next = add nuw nsw i64 %iv, 1
-  %exitcond.not = icmp eq i64 %iv.next, 0
+  %exitcond.not = icmp eq i64 %iv.next, %n
   br i1 %exitcond.not, label %exit, label %loop
 
 exit:
   %res = phi i32 [ %min.idx.next, %loop ]
   ret i32 %res
 }
 
 define ptr @test_with_ptr_index(ptr %start, ptr %end) {