1; RUN: opt < %s -globals-aa -gvn -S | FileCheck %s 2; 3; This tests the safe no-alias conclusions of GMR -- when there is 4; a non-escaping global as one indentified underlying object and some pointer 5; that would inherently have escaped any other function as the other underlying 6; pointer of an alias query. 7 8@g1 = internal global i32 0 9 10define i32 @test1(i32* %param) { 11; Ensure that we can fold a store to a load of a global across a store to 12; a parameter when the global is non-escaping. 13; 14; CHECK-LABEL: @test1( 15; CHECK: store i32 42, i32* @g1 16; CHECK-NOT: load i32 17; CHECK: ret i32 42 18entry: 19 store i32 42, i32* @g1 20 store i32 7, i32* %param 21 %v = load i32, i32* @g1 22 ret i32 %v 23} 24 25declare i32* @f() 26 27define i32 @test2() { 28; Ensure that we can fold a store to a load of a global across a store to 29; the pointer returned by a function call. Since the global could not escape, 30; this function cannot be returning its address. 31; 32; CHECK-LABEL: @test2( 33; CHECK: store i32 42, i32* @g1 34; CHECK-NOT: load i32 35; CHECK: ret i32 42 36entry: 37 %ptr = call i32* @f() readnone 38 store i32 42, i32* @g1 39 store i32 7, i32* %ptr 40 %v = load i32, i32* @g1 41 ret i32 %v 42} 43 44@g2 = external global i32* 45 46define i32 @test3() { 47; Ensure that we can fold a store to a load of a global across a store to 48; the pointer loaded from that global. Because the global does not escape, it 49; cannot alias a pointer loaded out of a global. 50; 51; CHECK-LABEL: @test3( 52; CHECK: store i32 42, i32* @g1 53; CHECK: store i32 7, i32* 54; CHECK-NOT: load i32 55; CHECK: ret i32 42 56entry: 57 store i32 42, i32* @g1 58 %ptr1 = load i32*, i32** @g2 59 store i32 7, i32* %ptr1 60 %v = load i32, i32* @g1 61 ret i32 %v 62} 63 64@g3 = internal global i32 1 65@g4 = internal global [10 x i32*] zeroinitializer 66 67define i32 @test4(i32* %param, i32 %n, i1 %c1, i1 %c2, i1 %c3) { 68; Ensure that we can fold a store to a load of a global across a store to 69; the pointer loaded from that global even when the load is behind PHIs and 70; selects, and there is a mixture of a load and another global or argument. 71; Note that we can't eliminate the load here because it is used in a PHI and 72; GVN doesn't try to do real DCE. The store is still forwarded by GVN though. 73; 74; CHECK-LABEL: @test4( 75; CHECK: store i32 42, i32* @g1 76; CHECK: store i32 7, i32* 77; CHECK: ret i32 42 78entry: 79 %call = call i32* @f() 80 store i32 42, i32* @g1 81 %ptr1 = load i32*, i32** @g2 82 %ptr2 = select i1 %c1, i32* %ptr1, i32* %param 83 %ptr3 = select i1 %c3, i32* %ptr2, i32* @g3 84 br label %loop 85 86loop: 87 %iv = phi i32 [ 0, %entry ], [ %inc, %loop ] 88 %ptr = phi i32* [ %ptr3, %entry ], [ %ptr5, %loop ] 89 store i32 7, i32* %ptr 90 %ptr4 = load i32*, i32** getelementptr ([10 x i32*], [10 x i32*]* @g4, i32 0, i32 1) 91 %ptr5 = select i1 %c2, i32* %ptr4, i32* %call 92 %inc = add i32 %iv, 1 93 %test = icmp slt i32 %inc, %n 94 br i1 %test, label %loop, label %exit 95 96exit: 97 %v = load i32, i32* @g1 98 ret i32 %v 99} 100 101define i32 @test5(i32** %param) { 102; Ensure that we can fold a store to a load of a global across a store to 103; a parameter that has been dereferenced when the global is non-escaping. 104; 105; CHECK-LABEL: @test5( 106; CHECK: %p = load i32* 107; CHECK: store i32 42, i32* @g1 108; CHECK-NOT: load i32 109; CHECK: ret i32 42 110entry: 111 %p = load i32*, i32** %param 112 store i32 42, i32* @g1 113 store i32 7, i32* %p 114 %v = load i32, i32* @g1 115 ret i32 %v 116} 117