Make instsimplify's analysis of icmp eq/ne use computeKnownBits to determine whether the icmp is always true or false. Patch by Suyog Sarda!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211251 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 20 insertions, 1 deletions

diff --git a/test/Transforms/InstCombine/align-2d-gep.ll b/test/Transforms/InstCombine/align-2d-gep.ll
index 5bca46d5a2..f6a877684c 100644
--- a/test/Transforms/InstCombine/align-2d-gep.ll
+++ b/test/Transforms/InstCombine/align-2d-gep.ll
@@ -31,7 +31,7 @@ bb1:
   store <2 x double><double 0.0, double 0.0>, <2 x double>* %r, align 8
 
   %indvar.next = add i64 %j, 2
-  %exitcond = icmp eq i64 %indvar.next, 557
+  %exitcond = icmp eq i64 %indvar.next, 556
   br i1 %exitcond, label %bb11, label %bb1
 
 bb11:
diff --git a/test/Transforms/InstSimplify/compare.ll b/test/Transforms/InstSimplify/compare.ll
index 105e244ed8..89fd6362d7 100644
--- a/test/Transforms/InstSimplify/compare.ll
+++ b/test/Transforms/InstSimplify/compare.ll
@@ -883,3 +883,22 @@ define i1 @returns_nonnull() {
 ; CHECK: ret i1 false
 }
 
+; If a bit is known to be zero for A and known to be one for B,
+; then A and B cannot be equal.
+define i1 @icmp_eq_const(i32 %a) nounwind {
+  %b = mul nsw i32 %a, -2
+  %c = icmp eq i32 %b, 1
+  ret i1 %c
+
+; CHECK-LABEL: @icmp_eq_const
+; CHECK-NEXT: ret i1 false 
+}
+
+define i1 @icmp_ne_const(i32 %a) nounwind {
+  %b = mul nsw i32 %a, -2
+  %c = icmp ne i32 %b, 1
+  ret i1 %c
+
+; CHECK-LABEL: @icmp_ne_const
+; CHECK-NEXT: ret i1 true
+}