[ValueTracking] Teach isImpliedCondition a new bitwise trick
Summary:
This change teaches isImpliedCondition to prove things like
(A | 15) < L ==> (A | 14) < L
if the low 4 bits of A are known to be zero.
Depends on D14391
Reviewers: majnemer, reames, hfinkel
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D14392
llvm-svn: 252673
diff --git a/llvm/test/Transforms/InstSimplify/implies.ll b/llvm/test/Transforms/InstSimplify/implies.ll
index eb8db42..2e3c959 100644
--- a/llvm/test/Transforms/InstSimplify/implies.ll
+++ b/llvm/test/Transforms/InstSimplify/implies.ll
@@ -127,6 +127,84 @@
ret i1 %res
}
+define i1 @test10(i32 %length.i, i32 %x.full) {
+; CHECK-LABEL: @test10(
+; CHECK: ret i1 true
+
+ %x = and i32 %x.full, 4294901760 ;; 4294901760 == 0xffff0000
+ %large = or i32 %x, 100
+ %small = or i32 %x, 90
+ %known = icmp ult i32 %large, %length.i
+ %to.prove = icmp ult i32 %small, %length.i
+ %res = icmp ule i1 %known, %to.prove
+ ret i1 %res
+}
+
+define i1 @test11(i32 %length.i, i32 %x) {
+; CHECK-LABEL: @test11(
+; CHECK: %res = icmp ule i1 %known, %to.prove
+; CHECK: ret i1 %res
+
+ %large = or i32 %x, 100
+ %small = or i32 %x, 90
+ %known = icmp ult i32 %large, %length.i
+ %to.prove = icmp ult i32 %small, %length.i
+ %res = icmp ule i1 %known, %to.prove
+ ret i1 %res
+}
+
+define i1 @test12(i32 %length.i, i32 %x.full) {
+; CHECK-LABEL: @test12(
+; CHECK: %res = icmp ule i1 %known, %to.prove
+; CHECK: ret i1 %res
+
+ %x = and i32 %x.full, 4294901760 ;; 4294901760 == 0xffff0000
+ %large = or i32 %x, 65536 ;; 65536 == 0x00010000
+ %small = or i32 %x, 90
+ %known = icmp ult i32 %large, %length.i
+ %to.prove = icmp ult i32 %small, %length.i
+ %res = icmp ule i1 %known, %to.prove
+ ret i1 %res
+}
+
+define i1 @test13(i32 %length.i, i32 %x) {
+; CHECK-LABEL: @test13(
+; CHECK: ret i1 true
+
+ %large = add nuw i32 %x, 100
+ %small = add nuw i32 %x, 90
+ %known = icmp ult i32 %large, %length.i
+ %to.prove = icmp ult i32 %small, %length.i
+ %res = icmp ule i1 %known, %to.prove
+ ret i1 %res
+}
+
+define i1 @test14(i32 %length.i, i32 %x.full) {
+; CHECK-LABEL: @test14(
+; CHECK: ret i1 true
+
+ %x = and i32 %x.full, 4294905615 ;; 4294905615 == 0xffff0f0f
+ %large = or i32 %x, 8224 ;; == 0x2020
+ %small = or i32 %x, 4112 ;; == 0x1010
+ %known = icmp ult i32 %large, %length.i
+ %to.prove = icmp ult i32 %small, %length.i
+ %res = icmp ule i1 %known, %to.prove
+ ret i1 %res
+}
+
+define i1 @test15(i32 %length.i, i32 %x) {
+; CHECK-LABEL: @test15(
+; CHECK: %res = icmp ule i1 %known, %to.prove
+; CHECK: ret i1 %res
+
+ %large = add nuw i32 %x, 100
+ %small = add nuw i32 %x, 110
+ %known = icmp ult i32 %large, %length.i
+ %to.prove = icmp ult i32 %small, %length.i
+ %res = icmp ule i1 %known, %to.prove
+ ret i1 %res
+}
+
; X >=(s) Y == X ==> Y (i1 1 becomes -1 for reasoning)
define i1 @test_sge(i32 %length.i, i32 %i) {
; CHECK-LABEL: @test_sge