[llvm-branch-commits] [llvm] [LoopInterchange] Fix test phi-ordering.ll (NFC) (PR #181989)
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Wed Feb 18 03:09:08 PST 2026
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: Ryotaro Kasuga (kasuga-fj)
<details>
<summary>Changes</summary>
I found that the test phi-ordering.ll is a bit fragile and can fail with any irrelevant changes. Also this test is not consistent with the following comment, which is at the top of the file:
```
;; Checks the order of the inner phi nodes does not cause havoc.
;; The inner loop has a reduction into c. The IV is not the first phi.
```
After examining the change history, I found that the original intent of this test was effectively lost in https://github.com/llvm/llvm-project/commit/c8bd6ea35e459169cbd401372e81168ed8482536. A workaround was introduced later in https://github.com/llvm/llvm-project/commit/eac34875109898ac01985f4afa937eec30c1c387 to preserve the test output, but this seems to have made the test more complicated.
This patch updates the test so that its original intent is restored. The change is close to a partial revert of https://github.com/llvm/llvm-project/commit/c8bd6ea35e459169cbd401372e81168ed8482536. Even though the feature for inner-only reductions has been removed, I believe it is still better to keep the test as it is, otherwise the test would be meaningless.
---
Full diff: https://github.com/llvm/llvm-project/pull/181989.diff
1 Files Affected:
- (modified) llvm/test/Transforms/LoopInterchange/phi-ordering.ll (+37-32)
``````````diff
diff --git a/llvm/test/Transforms/LoopInterchange/phi-ordering.ll b/llvm/test/Transforms/LoopInterchange/phi-ordering.ll
index 1f68528cb0ddf..2bdb4bf3a0037 100644
--- a/llvm/test/Transforms/LoopInterchange/phi-ordering.ll
+++ b/llvm/test/Transforms/LoopInterchange/phi-ordering.ll
@@ -1,55 +1,57 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
; RUN: opt < %s -passes=loop-interchange -cache-line-size=64 -verify-dom-info -verify-loop-info -verify-scev -verify-loop-lcssa -loop-interchange-threshold=0 -S 2>&1 | FileCheck %s
-;; Checks the order of the inner phi nodes does not cause havoc.
-;; The inner loop has a reduction into c. The IV is not the first phi.
target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
-
+; Checks the order of the inner phi nodes does not cause havoc.
+; The inner loop has a reduction into C. The IV is not the first phi.
+;
+; for (i = 0; i < 90; i++)
+; for (j = 0; j < 90; j++) {
+; red = C[i][j];
+; for (k = 1; k < 90; k++) {
+; red += A[i][k];
+; }
+; C[i][j] = red;
+; }
+;
+; NOTE: Currently inner-only reductions are not supported by loop-interchange,
+; so no transformation will be performed.
; Function Attrs: norecurse nounwind
define void @test(i32 %T, ptr noalias nocapture %C, ptr noalias nocapture readonly %A, ptr noalias nocapture readonly %B) local_unnamed_addr #0 {
; CHECK-LABEL: define void @test(
; CHECK-SAME: i32 [[T:%.*]], ptr noalias captures(none) [[C:%.*]], ptr noalias readonly captures(none) [[A:%.*]], ptr noalias readonly captures(none) [[B:%.*]]) local_unnamed_addr {
-; CHECK-NEXT: [[ENTRY:.*:]]
-; CHECK-NEXT: br label %[[FOR3_PREHEADER:.*]]
-; CHECK: [[FOR1_HEADER_PREHEADER:.*]]:
+; CHECK-NEXT: [[ENTRY:.*]]:
; CHECK-NEXT: br label %[[FOR1_HEADER:.*]]
; CHECK: [[FOR1_HEADER]]:
-; CHECK-NEXT: [[I:%.*]] = phi i32 [ [[INC20:%.*]], %[[FOR1_INC19:.*]] ], [ 0, %[[FOR1_HEADER_PREHEADER]] ]
-; CHECK-NEXT: [[MUL:%.*]] = mul nsw i32 [[I]], 90
-; CHECK-NEXT: br label %[[FOR2_HEADER_PREHEADER:.*]]
-; CHECK: [[FOR2_HEADER_PREHEADER]]:
+; CHECK-NEXT: [[I:%.*]] = phi i32 [ [[INC20:%.*]], %[[FOR1_INC19:.*]] ], [ 0, %[[ENTRY]] ]
; CHECK-NEXT: br label %[[FOR2_HEADER:.*]]
; CHECK: [[FOR2_HEADER]]:
-; CHECK-NEXT: [[J:%.*]] = phi i32 [ [[INC17:%.*]], %[[FOR2_INC16:.*]] ], [ 0, %[[FOR2_HEADER_PREHEADER]] ]
-; CHECK-NEXT: br label %[[FOR3_SPLIT1:.*]]
-; CHECK: [[FOR3_PREHEADER]]:
+; CHECK-NEXT: [[J:%.*]] = phi i32 [ 0, %[[FOR1_HEADER]] ], [ [[INC17:%.*]], %[[FOR2_INC16:.*]] ]
+; CHECK-NEXT: [[GEP_C:%.*]] = getelementptr inbounds [90 x i32], ptr [[C]], i32 [[I]], i32 [[J]]
+; CHECK-NEXT: [[RED_INIT:%.*]] = load i32, ptr [[GEP_C]], align 4
; CHECK-NEXT: br label %[[FOR3:.*]]
; CHECK: [[FOR3]]:
-; CHECK-NEXT: [[K:%.*]] = phi i32 [ [[TMP1:%.*]], %[[FOR3_SPLIT:.*]] ], [ 1, %[[FOR3_PREHEADER]] ]
-; CHECK-NEXT: br label %[[FOR1_HEADER_PREHEADER]]
-; CHECK: [[FOR3_SPLIT1]]:
-; CHECK-NEXT: [[ADD:%.*]] = add nsw i32 [[K]], [[MUL]]
-; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds [90 x [90 x i16]], ptr [[A]], i32 [[ADD]], i32 [[I]], i32 [[J]]
+; CHECK-NEXT: [[RED:%.*]] = phi i32 [ [[RED_INIT]], %[[FOR2_HEADER]] ], [ [[ADD15:%.*]], %[[FOR3]] ]
+; CHECK-NEXT: [[K:%.*]] = phi i32 [ 1, %[[FOR2_HEADER]] ], [ [[INC:%.*]], %[[FOR3]] ]
+; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds [90 x i16], ptr [[A]], i32 [[I]], i32 [[K]]
; CHECK-NEXT: [[TMP0:%.*]] = load i16, ptr [[ARRAYIDX]], align 2
-; CHECK-NEXT: [[ADD15:%.*]] = add nsw i16 [[TMP0]], 1
-; CHECK-NEXT: store i16 [[ADD15]], ptr [[ARRAYIDX]], align 2
-; CHECK-NEXT: [[INC:%.*]] = add nuw nsw i32 [[K]], 1
+; CHECK-NEXT: [[CONV:%.*]] = sext i16 [[TMP0]] to i32
+; CHECK-NEXT: [[ADD15]] = add nsw i32 [[CONV]], [[RED]]
+; CHECK-NEXT: [[INC]] = add nuw nsw i32 [[K]], 1
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i32 [[INC]], 90
-; CHECK-NEXT: br label %[[FOR2_INC16]]
-; CHECK: [[FOR3_SPLIT]]:
-; CHECK-NEXT: [[TMP1]] = add nuw nsw i32 [[K]], 1
-; CHECK-NEXT: [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 90
-; CHECK-NEXT: br i1 [[TMP2]], label %[[FOR1_LOOPEXIT:.*]], label %[[FOR3]]
+; CHECK-NEXT: br i1 [[EXITCOND]], label %[[FOR2_INC16]], label %[[FOR3]]
; CHECK: [[FOR2_INC16]]:
+; CHECK-NEXT: [[RED_LCSSA:%.*]] = phi i32 [ [[RED]], %[[FOR3]] ]
+; CHECK-NEXT: store i32 [[RED_LCSSA]], ptr [[GEP_C]], align 4
; CHECK-NEXT: [[INC17]] = add nuw nsw i32 [[J]], 1
; CHECK-NEXT: [[EXITCOND47:%.*]] = icmp eq i32 [[INC17]], 90
; CHECK-NEXT: br i1 [[EXITCOND47]], label %[[FOR1_INC19]], label %[[FOR2_HEADER]]
; CHECK: [[FOR1_INC19]]:
; CHECK-NEXT: [[INC20]] = add nuw nsw i32 [[I]], 1
; CHECK-NEXT: [[EXITCOND48:%.*]] = icmp eq i32 [[INC20]], 90
-; CHECK-NEXT: br i1 [[EXITCOND48]], label %[[FOR3_SPLIT]], label %[[FOR1_HEADER]]
+; CHECK-NEXT: br i1 [[EXITCOND48]], label %[[FOR1_LOOPEXIT:.*]], label %[[FOR1_HEADER]]
; CHECK: [[FOR1_LOOPEXIT]]:
; CHECK-NEXT: br label %[[EXIT:.*]]
; CHECK: [[EXIT]]:
@@ -60,25 +62,28 @@ entry:
for1.header: ; preds = %entry
%i = phi i32 [ %inc20, %for1.inc19 ], [ 0, %entry ]
- %mul = mul nsw i32 %i, 90
br label %for2.header
for2.header: ; preds = %for2.inc16, %for1.header
%j = phi i32 [ 0, %for1.header ], [ %inc17, %for2.inc16 ]
+ %gep.c = getelementptr inbounds [90 x i32], ptr %C, i32 %i, i32 %j
+ %red.init = load i32, ptr %gep.c
br label %for3
for3: ; preds = %for3, %for2.header
+ %red = phi i32 [ %red.init, %for2.header ], [ %add15, %for3 ]
%k = phi i32 [ 1, %for2.header ], [ %inc, %for3 ]
- %add = add nsw i32 %k, %mul
- %arrayidx = getelementptr inbounds [90 x [90 x i16]], ptr %A, i32 %add, i32 %i, i32 %j
+ %arrayidx = getelementptr inbounds [90 x i16], ptr %A, i32 %i, i32 %k
%0 = load i16, ptr %arrayidx, align 2
- %add15 = add nsw i16 %0, 1
- store i16 %add15, ptr %arrayidx
+ %conv = sext i16 %0 to i32
+ %add15 = add nsw i32 %conv, %red
%inc = add nuw nsw i32 %k, 1
%exitcond = icmp eq i32 %inc, 90
br i1 %exitcond, label %for2.inc16, label %for3
for2.inc16: ; preds = %for.body6
+ %red.lcssa = phi i32 [ %red, %for3 ]
+ store i32 %red.lcssa, ptr %gep.c
%inc17 = add nuw nsw i32 %j, 1
%exitcond47 = icmp eq i32 %inc17, 90
br i1 %exitcond47, label %for1.inc19, label %for2.header
``````````
</details>
https://github.com/llvm/llvm-project/pull/181989
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