[llvm] ffb4735 - [SCEV] Precommit tests with signed counting down loop.

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2020-08-02T10:26:26+01:00
New Revision: ffb47352005f2006851a3dcc2083329f434b8730

URL: https://github.com/llvm/llvm-project/commit/ffb47352005f2006851a3dcc2083329f434b8730
DIFF: https://github.com/llvm/llvm-project/commit/ffb47352005f2006851a3dcc2083329f434b8730.diff

LOG: [SCEV] Precommit tests with signed counting down loop.

>From PR46939.

Added: 
    llvm/test/Analysis/ScalarEvolution/pr46939-trip-count-count-down.ll

Modified: 
    

Removed: 
    


################################################################################
diff  --git a/llvm/test/Analysis/ScalarEvolution/pr46939-trip-count-count-down.ll b/llvm/test/Analysis/ScalarEvolution/pr46939-trip-count-count-down.ll
new file mode 100644
index 000000000000..f1001ecec0fd
--- /dev/null
+++ b/llvm/test/Analysis/ScalarEvolution/pr46939-trip-count-count-down.ll
@@ -0,0 +1,38 @@
+; RUN: opt -analyze -scalar-evolution %s 2>&1 | FileCheck %s
+
+declare void @iteration()
+
+define void @reverse_loop(i32 %n) {
+; CHECK-LABEL: 'reverse_loop'
+; CHECK-NEXT:  Classifying expressions for: @reverse_loop
+; CHECK-NEXT:    %i.011 = phi i32 [ %n, %for.body.lr.ph ], [ %dec, %for.body ]
+; CHECK-NEXT:    --> {%n,+,-1}<nsw><%for.body> U: full-set S: full-set Exits: (0 smin %n) LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT:    %dec = add nsw i32 %i.011, -1
+; CHECK-NEXT:    --> {(-1 + %n),+,-1}<nw><%for.body> U: full-set S: full-set Exits: (-1 + (0 smin %n)) LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT:  Determining loop execution counts for: @reverse_loop
+; CHECK-NEXT:  Loop %for.body: backedge-taken count is ((-1 * (0 smin %n)) + %n)
+; CHECK-NEXT:  Loop %for.body: max backedge-taken count is 2147483647
+; CHECK-NEXT:  Loop %for.body: Predicated backedge-taken count is ((-1 * (0 smin %n)) + %n)
+; CHECK-NEXT:   Predicates:
+; CHECK:       Loop %for.body: Trip multiple is 1
+;
+entry:
+  %cmp10 = icmp sgt i32 %n, -1
+  br i1 %cmp10, label %for.body.lr.ph, label %for.cond.cleanup
+
+for.body.lr.ph:
+  br label %for.body
+
+for.body:
+  %i.011 = phi i32 [ %n, %for.body.lr.ph ], [ %dec, %for.body ]
+  call void @iteration()
+  %dec = add nsw i32 %i.011, -1
+  %cmp = icmp sgt i32 %i.011, 0
+  br i1 %cmp, label %for.body, label %for.cond.cleanup.loopexit
+
+for.cond.cleanup.loopexit:
+  br label %for.cond.cleanup
+
+for.cond.cleanup:
+  ret void
+}