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

[Vikram Hegde via llvm-commits]

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

>From 5323693bfef99c7bd5396eefd743562f51187623 Mon Sep 17 00:00:00 2001
From: vikhegde <vikram.hegde at amd.com>
Date: Wed, 30 Apr 2025 13:21:58 +0530
Subject: [PATCH 1/3] [SCEV] reject comparision of pointers to different
 address spaces in SCEVWrapPredicate::implies

---
 llvm/lib/Analysis/ScalarEvolution.cpp         |  6 ++++
 .../LoopAccessAnalysis/nusw-predicates.ll     | 36 ++++++++++++++++++-
 2 files changed, 41 insertions(+), 1 deletion(-)

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
+ }

>From 5127939a5036b32b45220ad6e4485615a16e3296 Mon Sep 17 00:00:00 2001
From: vikhegde <vikram.hegde at amd.com>
Date: Wed, 30 Apr 2025 17:15:02 +0530
Subject: [PATCH 2/3] review comment

---
 llvm/lib/Analysis/ScalarEvolution.cpp | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index b39662ef90c05..83b5b59fbc4d9 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -14967,11 +14967,8 @@ 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;
-  }
+  if (Start->getType()->isPointerTy() && Start->getType() != OpStart->getType())
+    return false;
 
   const SCEV *Step = AR->getStepRecurrence(SE);
   const SCEV *OpStep = Op->AR->getStepRecurrence(SE);

>From aa5ff25e3f404bcf83a791f728266d10f4836f8a Mon Sep 17 00:00:00 2001
From: vikhegde <vikram.hegde at amd.com>
Date: Wed, 30 Apr 2025 19:11:16 +0530
Subject: [PATCH 3/3] add comment

---
 llvm/lib/Analysis/ScalarEvolution.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 83b5b59fbc4d9..43d200f1153d0 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -14967,6 +14967,7 @@ bool SCEVWrapPredicate::implies(const SCEVPredicate *N,
   if (Start->getType()->isPointerTy() != OpStart->getType()->isPointerTy())
     return false;
 
+  // Reject pointers to different address spaces.
   if (Start->getType()->isPointerTy() && Start->getType() != OpStart->getType())
     return false;