[llvm] Address post commit review comments (PR #84795)
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Mon Mar 11 09:59:32 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: None (annamthomas)
<details>
<summary>Changes</summary>
---
Full diff: https://github.com/llvm/llvm-project/pull/84795.diff
1 Files Affected:
- (added) llvm/test/Transforms/LoopVectorize/X86/pr81872.ll (+107)
``````````diff
diff --git a/llvm/test/Transforms/LoopVectorize/X86/pr81872.ll b/llvm/test/Transforms/LoopVectorize/X86/pr81872.ll
new file mode 100644
index 00000000000000..14acb6f57aa0c9
--- /dev/null
+++ b/llvm/test/Transforms/LoopVectorize/X86/pr81872.ll
@@ -0,0 +1,107 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -S -passes=loop-vectorize < %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; PR 81872 explains the issue.
+
+; If we vectorize, we have a miscompile where array IV and thereby value stored in (arr[99],
+; arr[98]) is calculated incorrectly since disjoint or was only disjoint because
+; of dominating conditions. Dropping the disjoint to avoid poison still changes
+; the behaviour since now the or is no longer equivalent to the add.
+;
+define void @test(ptr noundef align 8 dereferenceable_or_null(16) %arr) #0 {
+; CHECK-LABEL: define void @test(
+; CHECK-SAME: ptr noundef align 8 dereferenceable_or_null(16) [[ARR:%.*]]) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT: bb5:
+; CHECK-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]], !prof [[PROF0:![0-9]+]]
+; CHECK: vector.ph:
+; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
+; CHECK: vector.body:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT: [[VEC_IND:%.*]] = phi <4 x i64> [ <i64 99, i64 98, i64 97, i64 96>, [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT: [[OFFSET_IDX:%.*]] = sub i64 99, [[INDEX]]
+; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[OFFSET_IDX]], 0
+; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i64> poison, i64 [[INDEX]], i64 0
+; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT: [[VEC_IV:%.*]] = add <4 x i64> [[BROADCAST_SPLAT]], <i64 0, i64 1, i64 2, i64 3>
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ule <4 x i64> [[VEC_IV]], <i64 8, i64 8, i64 8, i64 8>
+; CHECK-NEXT: [[TMP2:%.*]] = and <4 x i64> [[VEC_IND]], <i64 1, i64 1, i64 1, i64 1>
+; CHECK-NEXT: [[TMP3:%.*]] = icmp eq <4 x i64> [[TMP2]], zeroinitializer
+; CHECK-NEXT: [[TMP4:%.*]] = select <4 x i1> [[TMP1]], <4 x i1> [[TMP3]], <4 x i1> zeroinitializer
+; CHECK-NEXT: [[TMP5:%.*]] = or i64 [[TMP0]], 1
+; CHECK-NEXT: [[TMP6:%.*]] = getelementptr i64, ptr [[ARR]], i64 [[TMP5]]
+; CHECK-NEXT: [[TMP7:%.*]] = getelementptr i64, ptr [[TMP6]], i32 0
+; CHECK-NEXT: [[TMP8:%.*]] = getelementptr i64, ptr [[TMP7]], i32 -3
+; CHECK-NEXT: [[REVERSE:%.*]] = shufflevector <4 x i1> [[TMP4]], <4 x i1> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: call void @llvm.masked.store.v4i64.p0(<4 x i64> <i64 1, i64 1, i64 1, i64 1>, ptr [[TMP8]], i32 8, <4 x i1> [[REVERSE]])
+; CHECK-NEXT: [[INDEX_NEXT]] = add i64 [[INDEX]], 4
+; CHECK-NEXT: [[VEC_IND_NEXT]] = add <4 x i64> [[VEC_IND]], <i64 -4, i64 -4, i64 -4, i64 -4>
+; CHECK-NEXT: [[TMP9:%.*]] = icmp eq i64 [[INDEX_NEXT]], 12
+; CHECK-NEXT: br i1 [[TMP9]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !prof [[PROF1:![0-9]+]], !llvm.loop [[LOOP2:![0-9]+]]
+; CHECK: middle.block:
+; CHECK-NEXT: br i1 true, label [[BB6:%.*]], label [[SCALAR_PH]]
+; CHECK: scalar.ph:
+; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ 87, [[MIDDLE_BLOCK]] ], [ 99, [[BB5:%.*]] ]
+; CHECK-NEXT: br label [[LOOP_HEADER:%.*]]
+; CHECK: loop.header:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], [[LOOP_LATCH:%.*]] ]
+; CHECK-NEXT: [[AND:%.*]] = and i64 [[IV]], 1
+; CHECK-NEXT: [[ICMP17:%.*]] = icmp eq i64 [[AND]], 0
+; CHECK-NEXT: br i1 [[ICMP17]], label [[BB18:%.*]], label [[LOOP_LATCH]], !prof [[PROF5:![0-9]+]]
+; CHECK: bb18:
+; CHECK-NEXT: [[OR:%.*]] = or disjoint i64 [[IV]], 1
+; CHECK-NEXT: [[GETELEMENTPTR19:%.*]] = getelementptr inbounds i64, ptr [[ARR]], i64 [[OR]]
+; CHECK-NEXT: store i64 1, ptr [[GETELEMENTPTR19]], align 8
+; CHECK-NEXT: br label [[LOOP_LATCH]]
+; CHECK: loop.latch:
+; CHECK-NEXT: [[IV_NEXT]] = add nsw i64 [[IV]], -1
+; CHECK-NEXT: [[ICMP22:%.*]] = icmp eq i64 [[IV_NEXT]], 90
+; CHECK-NEXT: br i1 [[ICMP22]], label [[BB6]], label [[LOOP_HEADER]], !prof [[PROF6:![0-9]+]], !llvm.loop [[LOOP7:![0-9]+]]
+; CHECK: bb6:
+; CHECK-NEXT: ret void
+;
+bb5:
+ br label %loop.header
+
+loop.header: ; preds = %loop.latch, %bb8
+ %iv = phi i64 [ 99, %bb5 ], [ %iv.next, %loop.latch ]
+ %and = and i64 %iv, 1
+ %icmp17 = icmp eq i64 %and, 0
+ br i1 %icmp17, label %bb18, label %loop.latch, !prof !21
+
+bb18: ; preds = %loop.header
+ %or = or disjoint i64 %iv, 1
+ %getelementptr19 = getelementptr inbounds i64, ptr %arr, i64 %or
+ store i64 1, ptr %getelementptr19, align 8
+ br label %loop.latch
+
+loop.latch: ; preds = %bb18, %loop.header
+ %iv.next = add nsw i64 %iv, -1
+ %icmp22 = icmp eq i64 %iv.next, 90
+ br i1 %icmp22, label %bb6, label %loop.header, !prof !22
+
+bb6:
+ ret void
+}
+
+attributes #0 = {"target-cpu"="haswell" "target-features"="+avx2" }
+
+!4 = !{}
+!10 = !{i32 1}
+!16 = !{i64 864}
+!17 = !{i64 8}
+!21 = !{!"branch_weights", i32 1, i32 1}
+!22 = !{!"branch_weights", i32 1, i32 95}
+
+
+;.
+; CHECK: [[PROF0]] = !{!"branch_weights", i32 1, i32 127}
+; CHECK: [[PROF1]] = !{!"branch_weights", i32 1, i32 23}
+; CHECK: [[LOOP2]] = distinct !{[[LOOP2]], [[META3:![0-9]+]], [[META4:![0-9]+]]}
+; CHECK: [[META3]] = !{!"llvm.loop.isvectorized", i32 1}
+; CHECK: [[META4]] = !{!"llvm.loop.unroll.runtime.disable"}
+; CHECK: [[PROF5]] = !{!"branch_weights", i32 1, i32 1}
+; CHECK: [[PROF6]] = !{!"branch_weights", i32 0, i32 0}
+; CHECK: [[LOOP7]] = distinct !{[[LOOP7]], [[META4]], [[META3]]}
+;.
``````````
</details>
https://github.com/llvm/llvm-project/pull/84795
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