Index: llvm/trunk/test/Transforms/InstCombine/known-non-zero.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/known-non-zero.ll
+++ llvm/trunk/test/Transforms/InstCombine/known-non-zero.ll
@@ -0,0 +1,93 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+declare i64 @llvm.cttz.i64(i64, i1)
+
+declare i64 @llvm.ctlz.i64(i64, i1)
+
+declare <8 x i64> @llvm.cttz.v8i64(<8 x i64>, i1)
+
+define i32 @test0(i64 %x) {
+; CHECK-LABEL: @test0(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i64 [[X:%.*]], 0
+; CHECK-NEXT:    br i1 [[C]], label [[EXIT:%.*]], label [[NON_ZERO:%.*]]
+; CHECK:       non_zero:
+; CHECK-NEXT:    [[CTZ:%.*]] = call i64 @llvm.cttz.i64(i64 [[X]], i1 false), !range !0
+; CHECK-NEXT:    [[CTZ32:%.*]] = trunc i64 [[CTZ]] to i32
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[RES:%.*]] = phi i32 [ [[CTZ32]], [[NON_ZERO]] ], [ 0, [[START:%.*]] ]
+; CHECK-NEXT:    ret i32 [[RES]]
+;
+start:
+  %c = icmp eq i64 %x, 0
+  br i1 %c, label %exit, label %non_zero
+
+non_zero:
+  %ctz = call i64 @llvm.cttz.i64(i64 %x, i1 false)
+  %ctz32 = trunc i64 %ctz to i32
+  br label %exit
+
+exit:
+  %res = phi i32 [ %ctz32, %non_zero ], [ 0, %start ]
+  ret i32 %res
+}
+
+define i32 @test1(i64 %x) {
+; CHECK-LABEL: @test1(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i64 [[X:%.*]], 0
+; CHECK-NEXT:    br i1 [[C]], label [[EXIT:%.*]], label [[NON_ZERO:%.*]]
+; CHECK:       non_zero:
+; CHECK-NEXT:    [[CTZ:%.*]] = call i64 @llvm.ctlz.i64(i64 [[X]], i1 false), !range !0
+; CHECK-NEXT:    [[CTZ32:%.*]] = trunc i64 [[CTZ]] to i32
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[RES:%.*]] = phi i32 [ [[CTZ32]], [[NON_ZERO]] ], [ 0, [[START:%.*]] ]
+; CHECK-NEXT:    ret i32 [[RES]]
+;
+start:
+  %c = icmp eq i64 %x, 0
+  br i1 %c, label %exit, label %non_zero
+
+non_zero:
+  %ctz = call i64 @llvm.ctlz.i64(i64 %x, i1 false)
+  %ctz32 = trunc i64 %ctz to i32
+  br label %exit
+
+exit:
+  %res = phi i32 [ %ctz32, %non_zero ], [ 0, %start ]
+  ret i32 %res
+}
+
+define <8 x i64> @test2(<8 x i64> %x) {
+; CHECK-LABEL: @test2(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    [[A:%.*]] = icmp eq <8 x i64> [[X:%.*]], zeroinitializer
+; CHECK-NEXT:    [[B:%.*]] = bitcast <8 x i1> [[A]] to i8
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i8 [[B]], 0
+; CHECK-NEXT:    br i1 [[C]], label [[EXIT:%.*]], label [[NON_ZERO:%.*]]
+; CHECK:       non_zero:
+; CHECK-NEXT:    [[CTZ:%.*]] = call <8 x i64> @llvm.cttz.v8i64(<8 x i64> [[X]], i1 false)
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[RES:%.*]] = phi <8 x i64> [ [[CTZ]], [[NON_ZERO]] ], [ zeroinitializer, [[START:%.*]] ]
+; CHECK-NEXT:    ret <8 x i64> [[RES]]
+;
+start:
+  %a = icmp eq <8 x i64> %x, zeroinitializer
+  %b = bitcast <8 x i1> %a to i8
+  %c = icmp eq i8 %b, 0
+  br i1 %c, label %exit, label %non_zero
+
+non_zero:
+  ; NB: We cannot determine that vectors are known to be zero based
+  ; on the dominating condition
+  %ctz = call <8 x i64> @llvm.cttz.v8i64(<8 x i64> %x, i1 false)
+  br label %exit
+
+exit:
+  %res = phi <8 x i64> [ %ctz, %non_zero ], [ zeroinitializer, %start ]
+  ret <8 x i64> %res
+}
Index: llvm/trunk/test/Transforms/InstSimplify/known-non-zero.ll
===================================================================
--- llvm/trunk/test/Transforms/InstSimplify/known-non-zero.ll
+++ llvm/trunk/test/Transforms/InstSimplify/known-non-zero.ll
@@ -0,0 +1,104 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instsimplify -S | FileCheck %s
+
+define i64 @test0(i64 %x) {
+; CHECK-LABEL: @test0(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    [[A:%.*]] = icmp eq i64 [[X:%.*]], 0
+; CHECK-NEXT:    br i1 [[A]], label [[EXIT:%.*]], label [[NON_ZERO:%.*]]
+; CHECK:       non_zero:
+; CHECK-NEXT:    [[B:%.*]] = icmp eq i64 [[X]], 0
+; CHECK-NEXT:    br i1 [[B]], label [[UNREACHABLE:%.*]], label [[EXIT]]
+; CHECK:       unreachable:
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[C:%.*]] = phi i64 [ 0, [[START:%.*]] ], [ 1, [[NON_ZERO]] ], [ 2, [[UNREACHABLE]] ]
+; CHECK-NEXT:    ret i64 [[C]]
+;
+start:
+  %a = icmp eq i64 %x, 0
+  br i1 %a, label %exit, label %non_zero
+
+non_zero:
+  %b = icmp eq i64 %x, 0
+  br i1 %b, label %unreachable, label %exit
+
+unreachable:
+  br label %exit
+
+exit:
+  %c = phi i64 [ 0, %start ], [ 1, %non_zero ], [ 2, %unreachable ]
+  ret i64 %c
+}
+
+define i64 @test1(i64 %x) {
+; CHECK-LABEL: @test1(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    [[A:%.*]] = icmp eq i64 [[X:%.*]], 0
+; CHECK-NEXT:    br i1 [[A]], label [[EXIT:%.*]], label [[NON_ZERO:%.*]]
+; CHECK:       non_zero:
+; CHECK-NEXT:    [[B:%.*]] = icmp ugt i64 [[X]], 0
+; CHECK-NEXT:    br i1 [[B]], label [[EXIT]], label [[UNREACHABLE:%.*]]
+; CHECK:       unreachable:
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[C:%.*]] = phi i64 [ 0, [[START:%.*]] ], [ [[X]], [[NON_ZERO]] ], [ 0, [[UNREACHABLE]] ]
+; CHECK-NEXT:    ret i64 [[C]]
+;
+start:
+  %a = icmp eq i64 %x, 0
+  br i1 %a, label %exit, label %non_zero
+
+non_zero:
+  %b = icmp ugt i64 %x, 0
+  br i1 %b, label %exit, label %unreachable
+
+unreachable:
+  br label %exit
+
+exit:
+  %c = phi i64 [ 0, %start ], [ %x, %non_zero ], [ 0, %unreachable ]
+  ret i64 %c
+}
+
+define i1 @test2(i64 %x, i1 %y) {
+; CHECK-LABEL: @test2(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    [[A:%.*]] = icmp eq i64 [[X:%.*]], 0
+; CHECK-NEXT:    br i1 [[A]], label [[EXIT:%.*]], label [[NON_ZERO:%.*]]
+; CHECK:       non_zero:
+; CHECK-NEXT:    br i1 [[Y:%.*]], label [[ONE:%.*]], label [[TWO:%.*]]
+; CHECK:       one:
+; CHECK-NEXT:    br label [[MAINBLOCK:%.*]]
+; CHECK:       two:
+; CHECK-NEXT:    br label [[MAINBLOCK]]
+; CHECK:       mainblock:
+; CHECK-NEXT:    [[P:%.*]] = phi i64 [ [[X]], [[ONE]] ], [ 42, [[TWO]] ]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i64 [[P]], 0
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[RES:%.*]] = phi i1 [ [[CMP]], [[MAINBLOCK]] ], [ true, [[START:%.*]] ]
+; CHECK-NEXT:    ret i1 [[RES]]
+;
+start:
+  %a = icmp eq i64 %x, 0
+  br i1 %a, label %exit, label %non_zero
+
+non_zero:
+  br i1 %y, label %one, label %two
+
+one:
+  br label %mainblock
+
+two:
+  br label %mainblock
+
+mainblock:
+  %p = phi i64 [ %x, %one ], [ 42, %two ]
+  %cmp = icmp eq i64 %p, 0
+  br label %exit
+
+exit:
+  %res = phi i1 [ %cmp, %mainblock ], [ 1, %start ]
+  ret i1 %res
+}