This patch teaches ScalarEvolution to pick and use !range metadata.

It also makes it more aggressive in querying range information by
adding a call to isKnownPredicateWithRanges to
isLoopBackedgeGuardedByCond and isLoopEntryGuardedByCond.

phabricator: http://reviews.llvm.org/D5638

Reviewed by: atrick, hfinkel

llvm-svn: 219532

1 files changed, 37 insertions, 0 deletions

diff --git a/llvm/test/Analysis/ScalarEvolution/load-with-range-metadata.ll b/llvm/test/Analysis/ScalarEvolution/load-with-range-metadata.ll
new file mode 100644
index 00000000000..2f6dcd0dad5
--- /dev/null
+++ b/llvm/test/Analysis/ScalarEvolution/load-with-range-metadata.ll
@@ -0,0 +1,37 @@
+; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s
+
+define i32 @slt_trip_count_with_range(i32 *%ptr0, i32 *%ptr1) {
+; CHECK-LABEL: slt_trip_count_with_range
+ entry:
+  %limit = load i32* %ptr0, !range !0
+  br label %loop
+
+ loop:
+; CHECK: Loop %loop: max backedge-taken count is 98
+  %index = phi i32 [ 0, %entry ], [ %index.inc, %loop ]
+  %index.inc = add i32 %index, 1
+  %continue = icmp slt i32 %index.inc, %limit
+  br i1 %continue, label %loop, label %loop.exit
+
+ loop.exit:
+  ret i32 0
+}
+
+define i32 @ult_trip_count_with_range(i32 *%ptr0, i32 *%ptr1) {
+; CHECK-LABEL: ult_trip_count_with_range
+ entry:
+  %limit = load i32* %ptr0, !range !0
+  br label %loop
+
+ loop:
+; CHECK: Loop %loop: max backedge-taken count is 98
+  %index = phi i32 [ 0, %entry ], [ %index.inc, %loop ]
+  %index.inc = add i32 %index, 1
+  %continue = icmp ult i32 %index.inc, %limit
+  br i1 %continue, label %loop, label %loop.exit
+
+ loop.exit:
+  ret i32 0
+}
+
+!0 = metadata !{i32 1, i32 100}