[PATCH] D91535: [IndVars] Use isLoopBackedgeGuardedByCond for last iteration check

[Max Kazantsev via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGf10500e220e3: [IndVars] Use isLoopBackedgeGuardedByCond for last iteration check (authored by mkazantsev).

Changed prior to commit:
  https://reviews.llvm.org/D91535?vs=305486&id=307753#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D91535/new/

https://reviews.llvm.org/D91535

Files:
  llvm/lib/Analysis/ScalarEvolution.cpp
  llvm/test/Transforms/IndVarSimplify/predicated_ranges.ll


Index: llvm/test/Transforms/IndVarSimplify/predicated_ranges.ll
===================================================================
--- llvm/test/Transforms/IndVarSimplify/predicated_ranges.ll
+++ llvm/test/Transforms/IndVarSimplify/predicated_ranges.ll
@@ -835,15 +835,16 @@
 ; CHECK-LABEL: @test_can_predicate_simple_unsigned_different_start(
 ; CHECK-NEXT:  preheader:
 ; CHECK-NEXT:    [[LEN:%.*]] = load i32, i32* [[P:%.*]], align 4
+; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[START:%.*]], -1
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
-; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[START:%.*]], [[PREHEADER:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[START]], [[PREHEADER:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
 ; CHECK-NEXT:    [[ZERO_COND:%.*]] = icmp eq i32 [[IV]], 0
 ; CHECK-NEXT:    br i1 [[ZERO_COND]], label [[EXIT:%.*]], label [[RANGE_CHECK_BLOCK:%.*]]
 ; CHECK:       range_check_block:
 ; CHECK-NEXT:    [[IV_NEXT]] = sub i32 [[IV]], 1
-; CHECK-NEXT:    [[RANGE_CHECK:%.*]] = icmp ult i32 [[IV_NEXT]], [[LEN]]
-; CHECK-NEXT:    br i1 [[RANGE_CHECK]], label [[BACKEDGE]], label [[FAIL:%.*]]
+; CHECK-NEXT:    [[RANGE_CHECK1:%.*]] = icmp ult i32 [[TMP0]], [[LEN]]
+; CHECK-NEXT:    br i1 [[RANGE_CHECK1]], label [[BACKEDGE]], label [[FAIL:%.*]]
 ; CHECK:       backedge:
 ; CHECK-NEXT:    [[EL_PTR:%.*]] = getelementptr i32, i32* [[P]], i32 [[IV]]
 ; CHECK-NEXT:    [[EL:%.*]] = load i32, i32* [[EL_PTR]], align 4
@@ -885,15 +886,16 @@
 ; CHECK-LABEL: @test_can_predicate_simple_unsigned_inverted_different_start(
 ; CHECK-NEXT:  preheader:
 ; CHECK-NEXT:    [[LEN:%.*]] = load i32, i32* [[P:%.*]], align 4
+; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[START:%.*]], -1
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
-; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[START:%.*]], [[PREHEADER:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[START]], [[PREHEADER:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
 ; CHECK-NEXT:    [[ZERO_COND:%.*]] = icmp eq i32 [[IV]], 0
 ; CHECK-NEXT:    br i1 [[ZERO_COND]], label [[EXIT:%.*]], label [[RANGE_CHECK_BLOCK:%.*]]
 ; CHECK:       range_check_block:
 ; CHECK-NEXT:    [[IV_NEXT]] = sub i32 [[IV]], 1
-; CHECK-NEXT:    [[RANGE_CHECK:%.*]] = icmp uge i32 [[IV_NEXT]], [[LEN]]
-; CHECK-NEXT:    br i1 [[RANGE_CHECK]], label [[FAIL:%.*]], label [[BACKEDGE]]
+; CHECK-NEXT:    [[RANGE_CHECK1:%.*]] = icmp uge i32 [[TMP0]], [[LEN]]
+; CHECK-NEXT:    br i1 [[RANGE_CHECK1]], label [[FAIL:%.*]], label [[BACKEDGE]]
 ; CHECK:       backedge:
 ; CHECK-NEXT:    [[EL_PTR:%.*]] = getelementptr i32, i32* [[P]], i32 [[IV]]
 ; CHECK-NEXT:    [[EL:%.*]] = load i32, i32* [[EL_PTR]], align 4
Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -9673,7 +9673,7 @@
   // Value of IV on suggested last iteration.
   const SCEV *Last = AR->evaluateAtIteration(MaxIter, *this);
   // Does it still meet the requirement?
-  if (!isKnownPredicateAt(Pred, Last, RHS, Context))
+  if (!isLoopBackedgeGuardedByCond(L, Pred, Last, RHS))
     return None;
   // Because step is +/- 1 and MaxIter has same type as Start (i.e. it does
   // not exceed max unsigned value of this type), this effectively proves


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