[ValueTracking] Use !range metadata more aggressively in KnownBits

Summary:
Teach `computeKnownBitsFromRangeMetadata` to use `!range` metadata more
aggressively.

Reviewers: majnemer, nlewycky, jingyue

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D14100

llvm-svn: 251487

1 files changed, 34 insertions, 0 deletions

diff --git a/llvm/test/Analysis/ValueTracking/known-bits-from-range-md.ll b/llvm/test/Analysis/ValueTracking/known-bits-from-range-md.ll
new file mode 100644
index 00000000000..e1de089b350
--- /dev/null
+++ b/llvm/test/Analysis/ValueTracking/known-bits-from-range-md.ll
@@ -0,0 +1,34 @@
+; RUN: opt -S -instsimplify < %s | FileCheck %s
+
+define i1 @test0(i8* %ptr) {
+; CHECK-LABEL: @test0(
+ entry:
+  %val = load i8, i8* %ptr, !range !{i8 -50, i8 0}
+  %and = and i8 %val, 128
+  %is.eq = icmp eq i8 %and, 128
+  ret i1 %is.eq
+; CHECK: ret i1 true
+}
+
+define i1 @test1(i8* %ptr) {
+; CHECK-LABEL: @test1(
+ entry:
+  %val = load i8, i8* %ptr, !range !{i8 64, i8 128}
+  %and = and i8 %val, 64
+  %is.eq = icmp eq i8 %and, 64
+  ret i1 %is.eq
+; CHECK: ret i1 true
+}
+
+define i1 @test2(i8* %ptr) {
+; CHECK-LABEL: @test2(
+ entry:
+; CHECK: load
+; CHECK: and
+; CHECK: icmp eq
+; CHECK: ret
+  %val = load i8, i8* %ptr, !range !{i8 64, i8 129}
+  %and = and i8 %val, 64
+  %is.eq = icmp eq i8 %and, 64
+  ret i1 %is.eq
+}