[llvm] 4d97a91 - [SCEV] Use umin_seq for symbolic max BE count

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2022-12-07T15:32:49+01:00
New Revision: 4d97a914d7aef6c95cd95669f99e5d32899e165a

URL: https://github.com/llvm/llvm-project/commit/4d97a914d7aef6c95cd95669f99e5d32899e165a
DIFF: https://github.com/llvm/llvm-project/commit/4d97a914d7aef6c95cd95669f99e5d32899e165a.diff

LOG: [SCEV] Use umin_seq for symbolic max BE count

We were using umin_seq when computing the exact BE count, but not
when computing the symbolic max BE count.

Added: 
    

Modified: 
    llvm/lib/Analysis/ScalarEvolution.cpp
    llvm/test/Analysis/ScalarEvolution/symbolic_max_exit_count.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 53601a8f3e90..1d3071048956 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -14789,7 +14789,7 @@ ScalarEvolution::computeSymbolicMaxBackedgeTakenCount(const Loop *L) {
   }
   if (ExitCounts.empty())
     return getCouldNotCompute();
-  return getUMinFromMismatchedTypes(ExitCounts);
+  return getUMinFromMismatchedTypes(ExitCounts, /*Sequential*/ true);
 }
 
 /// A rewriter to replace SCEV expressions in Map with the corresponding entry

diff  --git a/llvm/test/Analysis/ScalarEvolution/symbolic_max_exit_count.ll b/llvm/test/Analysis/ScalarEvolution/symbolic_max_exit_count.ll
index cb2af8d3967e..e63f7e45e8fc 100644
--- a/llvm/test/Analysis/ScalarEvolution/symbolic_max_exit_count.ll
+++ b/llvm/test/Analysis/ScalarEvolution/symbolic_max_exit_count.ll
@@ -412,7 +412,7 @@ define i32 @test_two_phis_simple(i32 %start_1, i32 %start_2, i32 %len) {
 ; CHECK-NEXT:    exit count for loop: %start_1
 ; CHECK-NEXT:    exit count for backedge: %start_2
 ; CHECK-NEXT:  Loop %loop: constant max backedge-taken count is -1
-; CHECK-NEXT:  Loop %loop: symbolic max backedge-taken count is (%start_1 umin %start_2)
+; CHECK-NEXT:  Loop %loop: symbolic max backedge-taken count is (%start_1 umin_seq %start_2)
 ; CHECK-NEXT:    symbolic max exit count for loop: %start_1
 ; CHECK-NEXT:    symbolic max exit count for backedge: %start_2
 ; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (%start_1 umin_seq %start_2)