[llvm-branch-commits] [llvm] release/18.x: [ValueTracking] Treat phi as underlying obj when not decomposing further (#84339) (PR #84950)
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Tue Mar 12 10:04:45 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-analysis
Author: None (llvmbot)
<details>
<summary>Changes</summary>
Backport 4cfd4a7896b5fd50274ec8573c259d7ad41741de b274b23665dec30f3ae4fb83ccca8b77e6d3ada3
Requested by: @<!-- -->nikic
---
Full diff: https://github.com/llvm/llvm-project/pull/84950.diff
2 Files Affected:
- (modified) llvm/lib/Analysis/ValueTracking.cpp (+2)
- (added) llvm/test/Analysis/LoopAccessAnalysis/underlying-object-loop-varying-phi.ll (+180)
``````````diff
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 412115eb649c2f..9f9451e4e814ac 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -5986,6 +5986,8 @@ void llvm::getUnderlyingObjects(const Value *V,
if (!LI || !LI->isLoopHeader(PN->getParent()) ||
isSameUnderlyingObjectInLoop(PN, LI))
append_range(Worklist, PN->incoming_values());
+ else
+ Objects.push_back(P);
continue;
}
diff --git a/llvm/test/Analysis/LoopAccessAnalysis/underlying-object-loop-varying-phi.ll b/llvm/test/Analysis/LoopAccessAnalysis/underlying-object-loop-varying-phi.ll
new file mode 100644
index 00000000000000..106dc8c13a49fa
--- /dev/null
+++ b/llvm/test/Analysis/LoopAccessAnalysis/underlying-object-loop-varying-phi.ll
@@ -0,0 +1,180 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -passes='print<access-info>' -disable-output %s 2>&1 | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
+
+; Test case for https://github.com/llvm/llvm-project/issues/82665.
+define void @indirect_ptr_recurrences_read_write(ptr %A, ptr %B) {
+; CHECK-LABEL: 'indirect_ptr_recurrences_read_write'
+; CHECK-NEXT: loop:
+; CHECK-NEXT: Report: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+; CHECK-NEXT: Unsafe indirect dependence.
+; CHECK-NEXT: Dependences:
+; CHECK-NEXT: IndidrectUnsafe:
+; CHECK-NEXT: %l = load i32, ptr %ptr.recur, align 4, !tbaa !4 ->
+; CHECK-NEXT: store i32 %xor, ptr %ptr.recur, align 4, !tbaa !4
+; CHECK-EMPTY:
+; CHECK-NEXT: Run-time memory checks:
+; CHECK-NEXT: Grouped accesses:
+; CHECK-EMPTY:
+; CHECK-NEXT: Non vectorizable stores to invariant address were not found in loop.
+; CHECK-NEXT: SCEV assumptions:
+; CHECK-EMPTY:
+; CHECK-NEXT: Expressions re-written:
+;
+entry:
+ br label %loop
+
+loop:
+ %iv = phi i64 [ 1, %entry ], [ %iv.next, %loop ]
+ %ptr.recur = phi ptr [ %A, %entry ], [ %ptr.next, %loop ]
+ %gep.B = getelementptr inbounds ptr, ptr %B, i64 %iv
+ %ptr.next = load ptr, ptr %gep.B, align 8, !tbaa !6
+ %l = load i32, ptr %ptr.recur, align 4, !tbaa !10
+ %xor = xor i32 %l, 1
+ store i32 %xor, ptr %ptr.recur, align 4, !tbaa !10
+ %iv.next = add nuw nsw i64 %iv, 1
+ %ec = icmp eq i64 %iv.next, 5
+ br i1 %ec, label %exit, label %loop
+
+exit:
+ ret void
+}
+
+define i32 @indirect_ptr_recurrences_read_only_loop(ptr %A, ptr %B) {
+; CHECK-LABEL: 'indirect_ptr_recurrences_read_only_loop'
+; CHECK-NEXT: loop:
+; CHECK-NEXT: Memory dependences are safe
+; CHECK-NEXT: Dependences:
+; CHECK-NEXT: Run-time memory checks:
+; CHECK-NEXT: Grouped accesses:
+; CHECK-EMPTY:
+; CHECK-NEXT: Non vectorizable stores to invariant address were not found in loop.
+; CHECK-NEXT: SCEV assumptions:
+; CHECK-EMPTY:
+; CHECK-NEXT: Expressions re-written:
+;
+entry:
+ br label %loop
+
+loop:
+ %iv = phi i64 [ 1, %entry ], [ %iv.next, %loop ]
+ %ptr.recur = phi ptr [ %A, %entry ], [ %ptr.next, %loop ]
+ %red = phi i32 [ 0, %entry ], [ %xor, %loop ]
+ %gep.B = getelementptr inbounds ptr, ptr %B, i64 %iv
+ %ptr.next = load ptr, ptr %gep.B, align 8, !tbaa !6
+ %l = load i32, ptr %ptr.recur, align 4, !tbaa !10
+ %xor = xor i32 %l, 1
+ %iv.next = add nuw nsw i64 %iv, 1
+ %ec = icmp eq i64 %iv.next, 5
+ br i1 %ec, label %exit, label %loop
+
+exit:
+ ret i32 %xor
+}
+
+define void @indirect_ptr_recurrences_read_write_may_alias_no_tbaa(ptr %A, ptr %B) {
+; CHECK-LABEL: 'indirect_ptr_recurrences_read_write_may_alias_no_tbaa'
+; CHECK-NEXT: loop:
+; CHECK-NEXT: Report: cannot identify array bounds
+; CHECK-NEXT: Dependences:
+; CHECK-NEXT: Run-time memory checks:
+; CHECK-NEXT: Grouped accesses:
+; CHECK-EMPTY:
+; CHECK-NEXT: Non vectorizable stores to invariant address were not found in loop.
+; CHECK-NEXT: SCEV assumptions:
+; CHECK-EMPTY:
+; CHECK-NEXT: Expressions re-written:
+;
+entry:
+ br label %loop
+
+loop:
+ %iv = phi i64 [ 1, %entry ], [ %iv.next, %loop ]
+ %ptr.recur = phi ptr [ %A, %entry ], [ %ptr.next, %loop ]
+ %gep.B = getelementptr inbounds ptr, ptr %B, i64 %iv
+ %ptr.next = load ptr, ptr %gep.B, align 8, !tbaa !6
+ %l = load i32, ptr %ptr.recur, align 4
+ %xor = xor i32 %l, 1
+ store i32 %xor, ptr %ptr.recur, align 4
+ %iv.next = add nuw nsw i64 %iv, 1
+ %ec = icmp eq i64 %iv.next, 5
+ br i1 %ec, label %exit, label %loop
+
+exit:
+ ret void
+}
+
+define void @indirect_ptr_recurrences_read_write_may_alias_different_obj(ptr %A, ptr %B, ptr %C) {
+; CHECK-LABEL: 'indirect_ptr_recurrences_read_write_may_alias_different_obj'
+; CHECK-NEXT: loop:
+; CHECK-NEXT: Report: cannot identify array bounds
+; CHECK-NEXT: Dependences:
+; CHECK-NEXT: Run-time memory checks:
+; CHECK-NEXT: Grouped accesses:
+; CHECK-EMPTY:
+; CHECK-NEXT: Non vectorizable stores to invariant address were not found in loop.
+; CHECK-NEXT: SCEV assumptions:
+; CHECK-EMPTY:
+; CHECK-NEXT: Expressions re-written:
+;
+entry:
+ br label %loop
+
+loop:
+ %iv = phi i64 [ 1, %entry ], [ %iv.next, %loop ]
+ %ptr.recur = phi ptr [ %A, %entry ], [ %ptr.next, %loop ]
+ %gep.B = getelementptr inbounds ptr, ptr %B, i64 %iv
+ %ptr.next = load ptr, ptr %gep.B, align 8, !tbaa !6
+ %l = load i32, ptr %ptr.recur, align 4
+ %xor = xor i32 %l, 1
+ %gep.C = getelementptr inbounds ptr, ptr %C, i64 %iv
+ store i32 %xor, ptr %gep.C, align 4
+ %iv.next = add nuw nsw i64 %iv, 1
+ %ec = icmp eq i64 %iv.next, 5
+ br i1 %ec, label %exit, label %loop
+
+exit:
+ ret void
+}
+
+define void @indirect_ptr_recurrences_read_write_may_noalias_different_obj(ptr %A, ptr %B, ptr noalias %C) {
+; CHECK-LABEL: 'indirect_ptr_recurrences_read_write_may_noalias_different_obj'
+; CHECK-NEXT: loop:
+; CHECK-NEXT: Memory dependences are safe
+; CHECK-NEXT: Dependences:
+; CHECK-NEXT: Run-time memory checks:
+; CHECK-NEXT: Grouped accesses:
+; CHECK-EMPTY:
+; CHECK-NEXT: Non vectorizable stores to invariant address were not found in loop.
+; CHECK-NEXT: SCEV assumptions:
+; CHECK-EMPTY:
+; CHECK-NEXT: Expressions re-written:
+;
+entry:
+ br label %loop
+
+loop:
+ %iv = phi i64 [ 1, %entry ], [ %iv.next, %loop ]
+ %ptr.recur = phi ptr [ %A, %entry ], [ %ptr.next, %loop ]
+ %gep.B = getelementptr inbounds ptr, ptr %B, i64 %iv
+ %ptr.next = load ptr, ptr %gep.B, align 8, !tbaa !6
+ %l = load i32, ptr %ptr.recur, align 4
+ %xor = xor i32 %l, 1
+ %gep.C = getelementptr inbounds ptr, ptr %C, i64 %iv
+ store i32 %xor, ptr %gep.C, align 4
+ %iv.next = add nuw nsw i64 %iv, 1
+ %ec = icmp eq i64 %iv.next, 5
+ br i1 %ec, label %exit, label %loop
+
+exit:
+ ret void
+}
+
+
+!6 = !{!7, !7, i64 0}
+!7 = !{!"any pointer", !8, i64 0}
+!8 = !{!"omnipotent char", !9, i64 0}
+!9 = !{!"Simple C/C++ TBAA"}
+!10 = !{!11, !11, i64 0}
+!11 = !{!"int", !8, i64 0}
``````````
</details>
https://github.com/llvm/llvm-project/pull/84950
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