[llvm] 8dcba20 - [SCEV] `getSequentialMinMaxExpr()`: relax 2-op umin_seq w/ constant to umin

[Roman Lebedev via llvm-commits]

Author: Roman Lebedev
Date: 2022-01-14T17:07:48+03:00
New Revision: 8dcba2067416b3f01221a229aa2a45ebdf3edf12

URL: https://github.com/llvm/llvm-project/commit/8dcba2067416b3f01221a229aa2a45ebdf3edf12
DIFF: https://github.com/llvm/llvm-project/commit/8dcba2067416b3f01221a229aa2a45ebdf3edf12.diff

LOG: [SCEV] `getSequentialMinMaxExpr()`: relax 2-op umin_seq w/ constant to umin

Currently, `computeExitLimitFromCondFromBinOp()` does that directly.

Added: 
    

Modified: 
    llvm/lib/Analysis/ScalarEvolution.cpp
    llvm/test/Analysis/ScalarEvolution/exit-count-select-safe.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 1025f30f0d8e..19eaf174885b 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -3994,6 +3994,11 @@ ScalarEvolution::getSequentialMinMaxExpr(SCEVTypes Kind,
   assert(!Ops.empty() && "Cannot get empty (u|s)(min|max)!");
   if (Ops.size() == 1)
     return Ops[0];
+  if (Ops.size() == 2 &&
+      any_of(Ops, [](const SCEV *Op) { return isa<SCEVConstant>(Op); }))
+    return getMinMaxExpr(
+        SCEVSequentialMinMaxExpr::getEquivalentNonSequentialSCEVType(Kind),
+        Ops);
 #ifndef NDEBUG
   Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
   for (unsigned i = 1, e = Ops.size(); i != e; ++i) {

diff  --git a/llvm/test/Analysis/ScalarEvolution/exit-count-select-safe.ll b/llvm/test/Analysis/ScalarEvolution/exit-count-select-safe.ll
index 2e4bb76ef482..3b25bb94b712 100644
--- a/llvm/test/Analysis/ScalarEvolution/exit-count-select-safe.ll
+++ b/llvm/test/Analysis/ScalarEvolution/exit-count-select-safe.ll
@@ -414,17 +414,17 @@ define i32 @logical_and_2ops_and_constant(i32 %n, i32 %m, i32 %k) {
 ; CHECK-LABEL: 'logical_and_2ops_and_constant'
 ; CHECK-NEXT:  Classifying expressions for: @logical_and_2ops_and_constant
 ; CHECK-NEXT:    %i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
-; CHECK-NEXT:    --> {0,+,1}<%loop> U: [0,43) S: [0,43) Exits: (%n umin_seq 42) LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    --> {0,+,1}<%loop> U: [0,43) S: [0,43) Exits: (42 umin %n) LoopDispositions: { %loop: Computable }
 ; CHECK-NEXT:    %i.next = add i32 %i, 1
-; CHECK-NEXT:    --> {1,+,1}<%loop> U: [1,44) S: [1,44) Exits: (1 + (%n umin_seq 42))<nuw><nsw> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    --> {1,+,1}<%loop> U: [1,44) S: [1,44) Exits: (1 + (42 umin %n))<nuw><nsw> LoopDispositions: { %loop: Computable }
 ; CHECK-NEXT:    %umin = call i32 @llvm.umin.i32(i32 %n, i32 42)
 ; CHECK-NEXT:    --> (42 umin %n) U: [0,43) S: [0,43) Exits: (42 umin %n) LoopDispositions: { %loop: Invariant }
 ; CHECK-NEXT:    %cond = select i1 %cond_p1, i1 true, i1 %cond_p0
 ; CHECK-NEXT:    --> %cond U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
 ; CHECK-NEXT:  Determining loop execution counts for: @logical_and_2ops_and_constant
-; CHECK-NEXT:  Loop %loop: backedge-taken count is (%n umin_seq 42)
+; CHECK-NEXT:  Loop %loop: backedge-taken count is (42 umin %n)
 ; CHECK-NEXT:  Loop %loop: max backedge-taken count is 42
-; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (%n umin_seq 42)
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (42 umin %n)
 ; CHECK-NEXT:   Predicates:
 ; CHECK:       Loop %loop: Trip multiple is 1
 ;