[llvm] 4b8eb89 - [tests] Cover a case brought up in review of D98222

[Philip Reames via llvm-commits]

Author: Philip Reames
Date: 2021-03-12T13:11:25-08:00
New Revision: 4b8eb894bfc39b99072fa1d99a348a4022c0cbfc

URL: https://github.com/llvm/llvm-project/commit/4b8eb894bfc39b99072fa1d99a348a4022c0cbfc
DIFF: https://github.com/llvm/llvm-project/commit/4b8eb894bfc39b99072fa1d99a348a4022c0cbfc.diff

LOG: [tests] Cover a case brought up in review of D98222

Added: 
    

Modified: 
    llvm/test/Analysis/ScalarEvolution/shift-recurrences.ll

Removed: 
    


################################################################################
diff  --git a/llvm/test/Analysis/ScalarEvolution/shift-recurrences.ll b/llvm/test/Analysis/ScalarEvolution/shift-recurrences.ll
index a81562f725ff..4eb9c9ea50a6 100644
--- a/llvm/test/Analysis/ScalarEvolution/shift-recurrences.ll
+++ b/llvm/test/Analysis/ScalarEvolution/shift-recurrences.ll
@@ -316,3 +316,70 @@ loop:
 exit:
   ret void
 }
+
+; Loop varying (but tightly bounded) shift amount
+define void @test_shl6(i1 %c) {
+; CHECK-LABEL: 'test_shl6'
+; CHECK-NEXT:  Classifying expressions for: @test_shl6
+; CHECK-NEXT:    %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT:    --> {0,+,1}<%loop> U: [0,5) S: [0,5) Exits: 4 LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %iv.shl = phi i64 [ 4, %entry ], [ %iv.shl.next, %loop ]
+; CHECK-NEXT:    --> %iv.shl U: [0,-3) S: [-9223372036854775808,9223372036854775805) Exits: 16 LoopDispositions: { %loop: Variant }
+; CHECK-NEXT:    %iv.next = add i64 %iv, 1
+; CHECK-NEXT:    --> {1,+,1}<%loop> U: [1,6) S: [1,6) Exits: 5 LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %shiftamt = and i64 %iv, 1
+; CHECK-NEXT:    --> (zext i1 {false,+,true}<%loop> to i64) U: [0,2) S: [0,2) Exits: 0 LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %iv.shl.next = shl i64 %iv.shl, %shiftamt
+; CHECK-NEXT:    --> %iv.shl.next U: [0,-3) S: [-9223372036854775808,9223372036854775805) Exits: 16 LoopDispositions: { %loop: Variant }
+; CHECK-NEXT:  Determining loop execution counts for: @test_shl6
+; CHECK-NEXT:  Loop %loop: backedge-taken count is 4
+; CHECK-NEXT:  Loop %loop: max backedge-taken count is 4
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is 4
+; CHECK-NEXT:   Predicates:
+; CHECK:       Loop %loop: Trip multiple is 5
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [0, %entry], [%iv.next, %loop]
+  %iv.shl = phi i64 [4, %entry], [%iv.shl.next, %loop]
+  %iv.next = add i64 %iv, 1
+  %shiftamt = and i64 %iv, 1
+  %iv.shl.next = shl i64 %iv.shl, %shiftamt
+  %cmp = icmp eq i64 %iv, 4
+  br i1 %cmp, label %exit, label %loop
+exit:
+  ret void
+}
+
+; Unanalyzeable shift amount
+define void @test_shl7(i1 %c, i64 %shiftamt) {
+; CHECK-LABEL: 'test_shl7'
+; CHECK-NEXT:  Classifying expressions for: @test_shl7
+; CHECK-NEXT:    %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT:    --> {0,+,1}<%loop> U: [0,5) S: [0,5) Exits: 4 LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %iv.shl = phi i64 [ 4, %entry ], [ %iv.shl.next, %loop ]
+; CHECK-NEXT:    --> %iv.shl U: [0,-3) S: [-9223372036854775808,9223372036854775805) Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
+; CHECK-NEXT:    %iv.next = add i64 %iv, 1
+; CHECK-NEXT:    --> {1,+,1}<%loop> U: [1,6) S: [1,6) Exits: 5 LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %iv.shl.next = shl i64 %iv.shl, %shiftamt
+; CHECK-NEXT:    --> %iv.shl.next U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
+; CHECK-NEXT:  Determining loop execution counts for: @test_shl7
+; CHECK-NEXT:  Loop %loop: backedge-taken count is 4
+; CHECK-NEXT:  Loop %loop: max backedge-taken count is 4
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is 4
+; CHECK-NEXT:   Predicates:
+; CHECK:       Loop %loop: Trip multiple is 5
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [0, %entry], [%iv.next, %loop]
+  %iv.shl = phi i64 [4, %entry], [%iv.shl.next, %loop]
+  %iv.next = add i64 %iv, 1
+  %iv.shl.next = shl i64 %iv.shl, %shiftamt
+  %cmp = icmp eq i64 %iv, 4
+  br i1 %cmp, label %exit, label %loop
+exit:
+  ret void
+}