[PATCH] D145231: [SCEV] Support mul in SCEVLoopGuardRewriter

[Dmitry Makogon via Phabricator via llvm-commits]

dmakogon created this revision.
dmakogon added reviewers: mkazantsev, fhahn, aleksandr.popov.
Herald added subscribers: StephenFan, javed.absar, hiraditya.
Herald added a project: All.
dmakogon requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Adds support for these SCEVs to cover more cases.


https://reviews.llvm.org/D145231

Files:
  llvm/lib/Analysis/ScalarEvolution.cpp
  llvm/test/Analysis/ScalarEvolution/trip-count-minmax.ll
  llvm/test/Analysis/ScalarEvolution/trip-count9.ll


Index: llvm/test/Analysis/ScalarEvolution/trip-count9.ll
===================================================================
--- llvm/test/Analysis/ScalarEvolution/trip-count9.ll
+++ llvm/test/Analysis/ScalarEvolution/trip-count9.ll
@@ -283,7 +283,7 @@
 ; CHECK-NEXT:  Loop %loop: symbolic max backedge-taken count is (-1 + (2 * %n))
 ; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (-1 + (2 * %n))
 ; CHECK-NEXT:   Predicates:
-; CHECK:       Loop %loop: Trip multiple is 2
+; CHECK:       Loop %loop: Trip multiple is 1
 ;
 entry:
   %m = shl i4 %n, 1
@@ -421,7 +421,7 @@
 ; CHECK-NEXT:  Loop %loop: symbolic max backedge-taken count is (-1 + (2 * %n))
 ; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (-1 + (2 * %n))
 ; CHECK-NEXT:   Predicates:
-; CHECK:       Loop %loop: Trip multiple is 2
+; CHECK:       Loop %loop: Trip multiple is 1
 ;
 entry:
   %m = shl i4 %n, 1
Index: llvm/test/Analysis/ScalarEvolution/trip-count-minmax.ll
===================================================================
--- llvm/test/Analysis/ScalarEvolution/trip-count-minmax.ll
+++ llvm/test/Analysis/ScalarEvolution/trip-count-minmax.ll
@@ -156,16 +156,16 @@
 ; CHECK-NEXT:    %cond = select i1 %cmp, i32 %mul, i32 %mul1
 ; CHECK-NEXT:    --> ((2 * %a)<nsw> smin (4 * %b)<nsw>) U: [0,-1) S: [-2147483648,2147483645)
 ; CHECK-NEXT:    %i.011 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
-; CHECK-NEXT:    --> {0,+,1}<nuw><nsw><%for.body> U: [0,-2147483648) S: [0,-2147483648) Exits: (-1 + ((2 * %a)<nsw> smin (4 * %b)<nsw>)) LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT:    --> {0,+,1}<nuw><nsw><%for.body> U: [0,2147483647) S: [0,2147483647) Exits: (-1 + ((2 * %a)<nsw> smin (4 * %b)<nsw>)) LoopDispositions: { %for.body: Computable }
 ; CHECK-NEXT:    %inc = add nuw nsw i32 %i.011, 1
-; CHECK-NEXT:    --> {1,+,1}<nuw><%for.body> U: [1,-1) S: [1,-1) Exits: ((2 * %a)<nsw> smin (4 * %b)<nsw>) LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT:    --> {1,+,1}<nuw><nsw><%for.body> U: [1,-2147483648) S: [1,-2147483648) Exits: ((2 * %a)<nsw> smin (4 * %b)<nsw>) LoopDispositions: { %for.body: Computable }
 ; CHECK-NEXT:  Determining loop execution counts for: @smin
 ; CHECK-NEXT:  Loop %for.body: backedge-taken count is (-1 + ((2 * %a)<nsw> smin (4 * %b)<nsw>))
-; CHECK-NEXT:  Loop %for.body: constant max backedge-taken count is -3
+; CHECK-NEXT:  Loop %for.body: constant max backedge-taken count is 2147483646
 ; CHECK-NEXT:  Loop %for.body: symbolic max backedge-taken count is (-1 + ((2 * %a)<nsw> smin (4 * %b)<nsw>))
 ; CHECK-NEXT:  Loop %for.body: Predicated backedge-taken count is (-1 + ((2 * %a)<nsw> smin (4 * %b)<nsw>))
 ; CHECK-NEXT:   Predicates:
-; CHECK:       Loop %for.body: Trip multiple is 2
+; CHECK:       Loop %for.body: Trip multiple is 1
 ;
 ; void smin(signed a, signed b) {
 ;   a *= 2;
Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -14971,6 +14971,13 @@
       return SCEVRewriteVisitor<SCEVLoopGuardRewriter>::visitSMinExpr(Expr);
     return I->second;
   }
+  
+  const SCEV *visitMulExpr(const SCEVMulExpr *Expr) {
+    auto I = Map.find(Expr);
+    if (I == Map.end())
+      return SCEVRewriteVisitor<SCEVLoopGuardRewriter>::visitMulExpr(Expr);
+    return I->second;
+  }
 };
 
 const SCEV *ScalarEvolution::applyLoopGuards(const SCEV *Expr, const Loop *L) {


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