[llvm] [LV] Adding/modifying pre-commit tests for changing loop interleaving count computation (PR #74689)

Wed Dec 6 18:40:15 PST 2023

llvmbot wrote:




@llvm/pr-subscribers-llvm-transforms

Author: Nilanjana Basu (nilanjana87)

<details>
<summary>Changes</summary>

Added/modified tests for evaluating changes to loop interleaving count computation in (https://github.com/llvm/llvm-project/pull/73766). The new set of tests address the change in IC computation to minimize the remainder TC of the vectorized loop while maximizing the IC when the remainder TC is the same.

---
Full diff: https://github.com/llvm/llvm-project/pull/74689.diff


1 Files Affected:

- (modified) llvm/test/Transforms/LoopVectorize/AArch64/interleave_count.ll (+179-10) 


``````````diff

diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/interleave_count.ll b/llvm/test/Transforms/LoopVectorize/AArch64/interleave_count.ll
index 061cdb5643671..a6642b72993ef 100644
--- a/llvm/test/Transforms/LoopVectorize/AArch64/interleave_count.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/interleave_count.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -tiny-trip-count-interleave-threshold=32 -p loop-vectorize -S -pass-remarks=loop-vectorize -disable-output 2>&1 | FileCheck %s
+; RUN: opt < %s -tiny-trip-count-interleave-threshold=16 -p loop-vectorize -S -pass-remarks=loop-vectorize -disable-output 2>&1 | FileCheck %s
 ; TODO: remove -tiny-trip-count-interleave-threshold once the interleave threshold is removed
 
 target triple = "aarch64-linux-gnu"
@@ -6,7 +6,7 @@ target triple = "aarch64-linux-gnu"
 %pair = type { i8, i8 }
 
 ; For this loop with known TC of 32, when the auto-vectorizer chooses VF 16, it should choose
-; IC 2 since there is no remainder loop run needed when the vector loop runs.
+; IC 2 since there is no remainder loop run needed after the vector loop runs.
 ; CHECK: remark: <unknown>:0:0: vectorized loop (vectorization width: 16, interleaved count: 2)
 define void @loop_with_tc_32(ptr noalias %p, ptr noalias %q) {
 entry:
@@ -29,8 +29,8 @@ for.end:
   ret void
 }
 
-; TODO: For this loop with known TC of 33, when the auto-vectorizer chooses VF 16, it should choose
-; IC 1 since there may be a remainder loop that needs to run after the vector loop.
+; For this loop with known TC of 33, when the auto-vectorizer chooses VF 16, it should choose
+; IC 2 since there is a small remainder loop TC that needs to run after the vector loop.
 ; CHECK: remark: <unknown>:0:0: vectorized loop (vectorization width: 16, interleaved count: 2)
 define void @loop_with_tc_33(ptr noalias %p, ptr noalias %q) {
 entry:
@@ -53,9 +53,104 @@ for.end:
   ret void
 }
 
-; For a loop with unknown trip count but a profile showing an approx TC estimate of 32, when the
-; auto-vectorizer chooses VF 16, it should choose IC 2 since chances are high that the remainder loop
-; won't need to run
+; For this loop with known TC of 39, when the auto-vectorizer chooses VF 16, it should choose
+; IC 2 since there is a small remainder loop that needs to run after the vector loop.
+; CHECK: remark: <unknown>:0:0: vectorized loop (vectorization width: 16, interleaved count: 2)
+define void @loop_with_tc_39(ptr noalias %p, ptr noalias %q) {
+entry:
+  br label %for.body
+
+for.body:
+  %i = phi i64 [ 0, %entry ], [ %i.next, %for.body ]
+  %tmp0 = getelementptr %pair, ptr %p, i64 %i, i32 0
+  %tmp1 = load i8, ptr %tmp0, align 1
+  %tmp2 = getelementptr %pair, ptr %p, i64 %i, i32 1
+  %tmp3 = load i8, ptr %tmp2, align 1
+  %add = add i8 %tmp1, %tmp3
+  %qi = getelementptr i8, ptr %q, i64 %i
+  store i8 %add, ptr %qi, align 1
+  %i.next = add nuw nsw i64 %i, 1
+  %cond = icmp eq i64 %i.next, 39
+  br i1 %cond, label %for.end, label %for.body
+
+for.end:
+  ret void
+}
+
+; TODO: For this loop with known TC of 48, when the auto-vectorizer chooses VF 16, it should choose
+; IC 1 since there will be no remainder loop that needs to run after the vector loop.
+; CHECK: remark: <unknown>:0:0: vectorized loop (vectorization width: 16, interleaved count: 2)
+define void @loop_with_tc_48(ptr noalias %p, ptr noalias %q) {
+entry:
+  br label %for.body
+
+for.body:
+  %i = phi i64 [ 0, %entry ], [ %i.next, %for.body ]
+  %tmp0 = getelementptr %pair, ptr %p, i64 %i, i32 0
+  %tmp1 = load i8, ptr %tmp0, align 1
+  %tmp2 = getelementptr %pair, ptr %p, i64 %i, i32 1
+  %tmp3 = load i8, ptr %tmp2, align 1
+  %add = add i8 %tmp1, %tmp3
+  %qi = getelementptr i8, ptr %q, i64 %i
+  store i8 %add, ptr %qi, align 1
+  %i.next = add nuw nsw i64 %i, 1
+  %cond = icmp eq i64 %i.next, 48
+  br i1 %cond, label %for.end, label %for.body
+
+for.end:
+  ret void
+}
+
+; TODO: For this loop with known TC of 49, when the auto-vectorizer chooses VF 16, it should choose
+; IC 1 since a remainder loop TC of 1 is more efficient than remainder loop TC of 17 with IC 2
+; CHECK: remark: <unknown>:0:0: vectorized loop (vectorization width: 16, interleaved count: 2)
+define void @loop_with_tc_49(ptr noalias %p, ptr noalias %q) {
+entry:
+  br label %for.body
+
+for.body:
+  %i = phi i64 [ 0, %entry ], [ %i.next, %for.body ]
+  %tmp0 = getelementptr %pair, ptr %p, i64 %i, i32 0
+  %tmp1 = load i8, ptr %tmp0, align 1
+  %tmp2 = getelementptr %pair, ptr %p, i64 %i, i32 1
+  %tmp3 = load i8, ptr %tmp2, align 1
+  %add = add i8 %tmp1, %tmp3
+  %qi = getelementptr i8, ptr %q, i64 %i
+  store i8 %add, ptr %qi, align 1
+  %i.next = add nuw nsw i64 %i, 1
+  %cond = icmp eq i64 %i.next, 49
+  br i1 %cond, label %for.end, label %for.body
+
+for.end:
+  ret void
+}
+
+; TODO: For this loop with known TC of 55, when the auto-vectorizer chooses VF 16, it should choose
+; IC 1 since a remainder loop TC of 7 is more efficient than remainder loop TC of 23 with IC 2
+; CHECK: remark: <unknown>:0:0: vectorized loop (vectorization width: 16, interleaved count: 2)
+define void @loop_with_tc_55(ptr noalias %p, ptr noalias %q) {
+entry:
+  br label %for.body
+
+for.body:
+  %i = phi i64 [ 0, %entry ], [ %i.next, %for.body ]
+  %tmp0 = getelementptr %pair, ptr %p, i64 %i, i32 0
+  %tmp1 = load i8, ptr %tmp0, align 1
+  %tmp2 = getelementptr %pair, ptr %p, i64 %i, i32 1
+  %tmp3 = load i8, ptr %tmp2, align 1
+  %add = add i8 %tmp1, %tmp3
+  %qi = getelementptr i8, ptr %q, i64 %i
+  store i8 %add, ptr %qi, align 1
+  %i.next = add nuw nsw i64 %i, 1
+  %cond = icmp eq i64 %i.next, 55
+  br i1 %cond, label %for.end, label %for.body
+
+for.end:
+  ret void
+}
+
+; TODO: For a loop with a profile-guided estimated TC of 32, when the auto-vectorizer chooses VF 16, 
+; it should conservatively choose IC 1 so that the vector loop runs twice at least
 ; CHECK: remark: <unknown>:0:0: vectorized loop (vectorization width: 16, interleaved count: 2)
 define void @loop_with_profile_tc_32(ptr noalias %p, ptr noalias %q, i64 %n) {
 entry:
@@ -78,9 +173,8 @@ for.end:
   ret void
 }
 
-; TODO: For a loop with unknown trip count but a profile showing an approx TC estimate of 33, 
-; when the auto-vectorizer chooses VF 16, it should choose IC 1 since chances are high that the 
-; remainder loop will need to run
+; TODO: For a loop with a profile-guided estimated TC of 33, when the auto-vectorizer chooses VF 16, 
+; it should conservatively choose IC 1 so that the vector loop runs twice at least
 ; CHECK: remark: <unknown>:0:0: vectorized loop (vectorization width: 16, interleaved count: 2)
 define void @loop_with_profile_tc_33(ptr noalias %p, ptr noalias %q, i64 %n) {
 entry:
@@ -103,5 +197,80 @@ for.end:
   ret void
 }
 
+; TODO: For a loop with a profile-guided estimated TC of 48, when the auto-vectorizer chooses VF 16, 
+; it should conservatively choose IC 1 so that the vector loop runs twice at least
+; CHECK: remark: <unknown>:0:0: vectorized loop (vectorization width: 16, interleaved count: 2)
+define void @loop_with_profile_tc_48(ptr noalias %p, ptr noalias %q, i64 %n) {
+entry:
+  br label %for.body
+
+for.body:
+  %i = phi i64 [ 0, %entry ], [ %i.next, %for.body ]
+  %tmp0 = getelementptr %pair, ptr %p, i64 %i, i32 0
+  %tmp1 = load i8, ptr %tmp0, align 1
+  %tmp2 = getelementptr %pair, ptr %p, i64 %i, i32 1
+  %tmp3 = load i8, ptr %tmp2, align 1
+  %add = add i8 %tmp1, %tmp3
+  %qi = getelementptr i8, ptr %q, i64 %i
+  store i8 %add, ptr %qi, align 1
+  %i.next = add nuw nsw i64 %i, 1
+  %cond = icmp eq i64 %i.next, %n
+  br i1 %cond, label %for.end, label %for.body, !prof !2
+
+for.end:
+  ret void
+}
+
+; TODO: For a loop with a profile-guided estimated TC of 63, when the auto-vectorizer chooses VF 16, 
+; it should conservatively choose IC 1 so that the vector loop runs twice at least
+; CHECK: remark: <unknown>:0:0: vectorized loop (vectorization width: 16, interleaved count: 2)
+define void @loop_with_profile_tc_63(ptr noalias %p, ptr noalias %q, i64 %n) {
+entry:
+  br label %for.body
+
+for.body:
+  %i = phi i64 [ 0, %entry ], [ %i.next, %for.body ]
+  %tmp0 = getelementptr %pair, ptr %p, i64 %i, i32 0
+  %tmp1 = load i8, ptr %tmp0, align 1
+  %tmp2 = getelementptr %pair, ptr %p, i64 %i, i32 1
+  %tmp3 = load i8, ptr %tmp2, align 1
+  %add = add i8 %tmp1, %tmp3
+  %qi = getelementptr i8, ptr %q, i64 %i
+  store i8 %add, ptr %qi, align 1
+  %i.next = add nuw nsw i64 %i, 1
+  %cond = icmp eq i64 %i.next, %n
+  br i1 %cond, label %for.end, label %for.body, !prof !3
+
+for.end:
+  ret void
+}
+
+; For a loop with a profile-guided estimated TC of 64, when the auto-vectorizer chooses VF 16, 
+; it should choose conservatively IC 2 so that the vector loop runs twice at least
+; CHECK: remark: <unknown>:0:0: vectorized loop (vectorization width: 16, interleaved count: 2)
+define void @loop_with_profile_tc_64(ptr noalias %p, ptr noalias %q, i64 %n) {
+entry:
+  br label %for.body
+
+for.body:
+  %i = phi i64 [ 0, %entry ], [ %i.next, %for.body ]
+  %tmp0 = getelementptr %pair, ptr %p, i64 %i, i32 0
+  %tmp1 = load i8, ptr %tmp0, align 1
+  %tmp2 = getelementptr %pair, ptr %p, i64 %i, i32 1
+  %tmp3 = load i8, ptr %tmp2, align 1
+  %add = add i8 %tmp1, %tmp3
+  %qi = getelementptr i8, ptr %q, i64 %i
+  store i8 %add, ptr %qi, align 1
+  %i.next = add nuw nsw i64 %i, 1
+  %cond = icmp eq i64 %i.next, %n
+  br i1 %cond, label %for.end, label %for.body, !prof !4
+
+for.end:
+  ret void
+}
+
 !0 = !{!"branch_weights", i32 1, i32 31}
 !1 = !{!"branch_weights", i32 1, i32 32}
+!2 = !{!"branch_weights", i32 1, i32 47}
+!3 = !{!"branch_weights", i32 1, i32 62}
+!4 = !{!"branch_weights", i32 1, i32 63}

``````````

</details>


https://github.com/llvm/llvm-project/pull/74689
