[PATCH] D143409: [SCEV][IndVarSimplify] Add nsw/nuw falgs to binary ops before visiting IVUsers

[Aleksandr Popov via Phabricator via llvm-commits]

aleksandr.popov updated this revision to Diff 496396.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D143409/new/

https://reviews.llvm.org/D143409

Files:
  llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
  llvm/test/Transforms/IndVarSimplify/cycled_phis.ll


Index: llvm/test/Transforms/IndVarSimplify/cycled_phis.ll
===================================================================
--- llvm/test/Transforms/IndVarSimplify/cycled_phis.ll
+++ llvm/test/Transforms/IndVarSimplify/cycled_phis.ll
@@ -67,7 +67,7 @@
   ret i32 %iv
 }
 
-; TODO: The 2nd check can be made invariant.
+; The 2nd check can be made invariant.
 ; slt and ult checks are equivalent. When IV is negative, slt check will pass and ult will
 ; fail. Because IV is incrementing, this will fail on 1st iteration or never.
 define i32 @unknown.start(i32 %start, ptr %len.ptr) {
@@ -82,7 +82,7 @@
 ; CHECK-NEXT:    [[SIGNED_CMP:%.*]] = icmp slt i32 [[IV]], [[LEN]]
 ; CHECK-NEXT:    br i1 [[SIGNED_CMP]], label [[SIGNED_PASSED:%.*]], label [[FAILED_SIGNED:%.*]]
 ; CHECK:       signed.passed:
-; CHECK-NEXT:    [[UNSIGNED_CMP:%.*]] = icmp ult i32 [[IV]], [[LEN]]
+; CHECK-NEXT:    [[UNSIGNED_CMP:%.*]] = icmp ult i32 [[START]], [[LEN]]
 ; CHECK-NEXT:    br i1 [[UNSIGNED_CMP]], label [[BACKEDGE]], label [[FAILED_UNSIGNED:%.*]]
 ; CHECK:       backedge:
 ; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i32 [[IV]], 1
@@ -132,7 +132,7 @@
 }
 
 
-; TODO: We should be able to prove that:
+; We should be able to prove that:
 ; - %sibling.iv.next is non-negative;
 ; - therefore, %iv is non-negative;
 ; - therefore, unsigned check can be removed.
@@ -155,11 +155,10 @@
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
 ; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[SIBLING_IV_NEXT_LCSSA]], [[PREHEADER]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
-; CHECK-NEXT:    [[SIGNED_CMP:%.*]] = icmp slt i32 [[IV]], [[LEN]]
+; CHECK-NEXT:    [[SIGNED_CMP:%.*]] = icmp ult i32 [[IV]], [[LEN]]
 ; CHECK-NEXT:    br i1 [[SIGNED_CMP]], label [[SIGNED_PASSED:%.*]], label [[FAILED_SIGNED:%.*]]
 ; CHECK:       signed.passed:
-; CHECK-NEXT:    [[UNSIGNED_CMP:%.*]] = icmp ult i32 [[IV]], [[LEN]]
-; CHECK-NEXT:    br i1 [[UNSIGNED_CMP]], label [[BACKEDGE]], label [[FAILED_UNSIGNED:%.*]]
+; CHECK-NEXT:    br i1 true, label [[BACKEDGE]], label [[FAILED_UNSIGNED:%.*]]
 ; CHECK:       backedge:
 ; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i32 [[IV]], 1
 ; CHECK-NEXT:    [[COND:%.*]] = call i1 @cond()
@@ -354,7 +353,7 @@
 ; CHECK-NEXT:    [[UNSIGNED_CMP:%.*]] = icmp ult i32 [[IV_START]], [[LEN]]
 ; CHECK-NEXT:    br i1 [[UNSIGNED_CMP]], label [[BACKEDGE]], label [[FAILED_UNSIGNED:%.*]]
 ; CHECK:       backedge:
-; CHECK-NEXT:    [[IV_NEXT]] = add nsw i32 [[IV]], 1
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i32 [[IV]], 1
 ; CHECK-NEXT:    [[COND:%.*]] = call i1 @cond()
 ; CHECK-NEXT:    br i1 [[COND]], label [[LOOP]], label [[OUTER_LOOP_BACKEDGE]]
 ; CHECK:       outer.loop.backedge:
@@ -472,7 +471,7 @@
 ; CHECK-NEXT:    [[UNSIGNED_CMP:%.*]] = icmp ult i32 [[IV_START]], [[LEN]]
 ; CHECK-NEXT:    br i1 [[UNSIGNED_CMP]], label [[BACKEDGE]], label [[FAILED_UNSIGNED:%.*]]
 ; CHECK:       backedge:
-; CHECK-NEXT:    [[IV_NEXT]] = add nsw i32 [[IV]], 1
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i32 [[IV]], 1
 ; CHECK-NEXT:    [[COND:%.*]] = call i1 @cond()
 ; CHECK-NEXT:    br i1 [[COND]], label [[LOOP]], label [[OUTER_LOOP_SELECTION:%.*]]
 ; CHECK:       outer.loop.selection:
Index: llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
===================================================================
--- llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
+++ llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
@@ -884,6 +884,14 @@
   // do for loop header phis that use each other.
   pushIVUsers(CurrIV, L, Simplified, SimpleIVUsers);
 
+  // Annotate binary operators primarily to give more context for analyzes and
+  // transformations with users, which are visited before binary operators. E.g.
+  // for IV comparison invariant making
+  for (auto [UseInst, IVOperand] : SimpleIVUsers)
+    if (BinaryOperator *BO = dyn_cast<BinaryOperator>(UseInst))
+      if (strengthenBinaryOp(BO, IVOperand))
+        pushIVUsers(IVOperand, L, Simplified, SimpleIVUsers);
+
   while (!SimpleIVUsers.empty()) {
     std::pair<Instruction*, Instruction*> UseOper =
       SimpleIVUsers.pop_back_val();


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D143409.496396.patch
Type: text/x-patch
Size: 4085 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20230210/f2f2a340/attachment.bin>