[llvm] [SCEV] Reject comparision of pointers to different address spaces in SCEVWrapPredicate::implies (PR #137935)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-analysis

Author: Vikram Hegde (vikramRH)

<details>
<summary>Changes</summary>

This is an attempt to fix a crash as seen here, https://godbolt.org/z/dqYzK17bj.  I'm not sure if this is too conservative/right way to handle this. would just comparing and rejecting the address sizes of different address spaces be enough ?

---
Full diff: https://github.com/llvm/llvm-project/pull/137935.diff


2 Files Affected:

- (modified) llvm/lib/Analysis/ScalarEvolution.cpp (+6) 
- (modified) llvm/test/Analysis/LoopAccessAnalysis/nusw-predicates.ll (+35-1) 


``````````diff
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 6055c3d791cb2..b39662ef90c05 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -14967,6 +14967,12 @@ bool SCEVWrapPredicate::implies(const SCEVPredicate *N,
   if (Start->getType()->isPointerTy() != OpStart->getType()->isPointerTy())
     return false;
 
+  if (Start->getType()->isPointerTy()) {
+    if (Start->getType()->getPointerAddressSpace() !=
+        OpStart->getType()->getPointerAddressSpace())
+      return false;
+  }
+
   const SCEV *Step = AR->getStepRecurrence(SE);
   const SCEV *OpStep = Op->AR->getStepRecurrence(SE);
   if (!SE.isKnownPositive(Step) || !SE.isKnownPositive(OpStep))
diff --git a/llvm/test/Analysis/LoopAccessAnalysis/nusw-predicates.ll b/llvm/test/Analysis/LoopAccessAnalysis/nusw-predicates.ll
index d4f7f82a8cff1..ab40a22a3274d 100644
--- a/llvm/test/Analysis/LoopAccessAnalysis/nusw-predicates.ll
+++ b/llvm/test/Analysis/LoopAccessAnalysis/nusw-predicates.ll
@@ -1,7 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 5
 ; RUN: opt -passes='print<access-info>' -disable-output %s 2>&1 | FileCheck %s
 
-target datalayout = "p:16:16"
+target datalayout = "p:16:16-p3:32:32"
 
 define void @int_and_pointer_predicate(ptr %v, i32 %N) {
 ; CHECK-LABEL: 'int_and_pointer_predicate'
@@ -124,3 +124,37 @@ loop:
 exit:
   ret void
 }
+
+define void @pointers_to_different_aspace_predicates(ptr %v, ptr addrspace(3) %w, i32 %N) {
+; CHECK-LABEL: 'pointers_to_different_aspace_predicates'
+; 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-NEXT:      {0,+,1}<%loop> Added Flags: <nusw>
+; CHECK-NEXT:      {%v,+,4}<%loop> Added Flags: <nusw>
+; CHECK-NEXT:      {%w,+,4}<%loop> Added Flags: <nusw>
+; CHECK-EMPTY:
+; CHECK-NEXT:      Expressions re-written:
+;
+entry:
+   br label %loop
+
+loop:
+   %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+   %gep.v = getelementptr {i16, i16}, ptr %v, i64 %iv
+   store i16 0, ptr %gep.v, align 1
+   %gep.w = getelementptr i32, ptr addrspace(3) %w, i64 %iv
+   store i32 0, ptr addrspace(3) %gep.w, align 1
+   %iv.next = add i64 %iv, 1
+   %iv.i32 = trunc i64 %iv to i32
+   %.not = icmp ult i32 %N, %iv.i32
+   br i1 %.not, label %exit, label %loop
+
+ exit:
+   ret void
+ }

``````````

</details>


https://github.com/llvm/llvm-project/pull/137935