[llvm] e034c3f - [SCEV] Add a few test cases where the max BTC is limited by wrapping.

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2020-10-16T09:53:32+01:00
New Revision: e034c3f7043a0f5a0b0af834a4b84d06e6b8948e

URL: https://github.com/llvm/llvm-project/commit/e034c3f7043a0f5a0b0af834a4b84d06e6b8948e
DIFF: https://github.com/llvm/llvm-project/commit/e034c3f7043a0f5a0b0af834a4b84d06e6b8948e.diff

LOG: [SCEV] Add a few test cases where the max BTC is limited by wrapping.

Added: 
    llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-limit-by-wrapping.ll

Modified: 
    

Removed: 
    


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diff  --git a/llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-limit-by-wrapping.ll b/llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-limit-by-wrapping.ll
new file mode 100644
index 000000000000..976c7d32eacb
--- /dev/null
+++ b/llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-limit-by-wrapping.ll
@@ -0,0 +1,48 @@
+; RUN: opt < %s -analyze -enable-new-pm=0 -scalar-evolution -scalar-evolution-max-iterations=0  -scalar-evolution-classify-expressions=0  | FileCheck %s
+; RUN: opt < %s -disable-output "-passes=print<scalar-evolution>" -scalar-evolution-max-iterations=0  -scalar-evolution-classify-expressions=0  2>&1 | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @max_backedge_taken_count_by_wrapping1(i8 %N, i8* %ptr) {
+; CHECK-LABEL: Determining loop execution counts for: @max_backedge_taken_count_by_wrapping1
+; CHECK-NEXT:  Loop %loop: backedge-taken count is (%N /u 4)
+; CHECK-NEXT:  Loop %loop: max backedge-taken count is 63
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (%N /u 4)
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i8 [ 0, %entry ], [ %iv.next, %loop ]
+  %gep = getelementptr i8, i8* %ptr, i8 %iv
+  store i8 %iv, i8* %gep
+  %iv.next = add nuw nsw i8 %iv, 4
+  %ec = icmp ne i8 %iv, %N
+  br i1 %ec, label %loop, label %exit
+
+exit:
+  ret void
+}
+
+; TODO: Max backedge taken count could be improved.
+define void @max_backedge_taken_count_by_wrapping2(i8 %N, i8* %ptr) {
+; CHECK-LABEL: Determining loop execution counts for: @max_backedge_taken_count_by_wrapping2
+; CHECK-NEXT:  Loop %loop: backedge-taken count is ((-128 + %N) /u 4)
+; CHECK-NEXT:  Loop %loop: max backedge-taken count is 63
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is ((-128 + %N) /u 4)
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i8 [ 128, %entry ], [ %iv.next, %loop ]
+  %gep = getelementptr i8, i8* %ptr, i8 %iv
+  store i8 %iv, i8* %gep
+  %iv.next = add nuw nsw i8 %iv, 4
+  %ec = icmp ne i8 %iv, %N
+  br i1 %ec, label %loop, label %exit
+
+exit:
+  ret void
+}